Amiga ISO Collection/AmigaUtilCD2.iso/Programming/Misc/TRSICAT.LZX/CATS_CD2_TRSI/Inc&AD1.3/Text_Autodocs/exec.doc

Text File | 1992-09-12 | 95.8 KB | 3,395 lines

TABLE OF CONTENTS

exec.library/AbortIO
exec.library/AddDevice
exec.library/AddHead
exec.library/AddIntServer
exec.library/AddLibrary
exec.library/AddMemList
exec.library/AddPort
exec.library/AddResource
exec.library/AddSemaphore
exec.library/AddTail
exec.library/AddTask
exec.library/Alert
exec.library/AllocAbs
exec.library/Allocate
exec.library/AllocEntry
exec.library/AllocMem
exec.library/AllocSignal
exec.library/AllocTrap
exec.library/AttemptSemaphore
exec.library/AvailMem
exec.library/Cause
exec.library/CheckIO
exec.library/CloseDevice
exec.library/CloseLibrary
exec.library/CopyMem
exec.library/CopyMemQuick
exec.library/Deallocate
exec.library/Debug
exec.library/Disable
exec.library/DoIO
exec.library/Enable
exec.library/Enqueue
exec.library/FindName
exec.library/FindPort
exec.library/FindResident
exec.library/FindSemaphore
exec.library/FindTask
exec.library/Forbid
exec.library/FreeEntry
exec.library/FreeMem
exec.library/FreeSignal
exec.library/FreeTrap
exec.library/GetCC
exec.library/GetMsg
exec.library/InitCode
exec.library/InitResident
exec.library/InitSemaphore
exec.library/InitStruct
exec.library/Insert
exec.library/MakeFunctions
exec.library/MakeLibrary
exec.library/ObtainSemaphore
exec.library/ObtainSemaphoreList
exec.library/OldOpenLibrary
exec.library/OpenDevice
exec.library/OpenLibrary
exec.library/OpenResource
exec.library/Permit
exec.library/Procure
exec.library/PutMsg
exec.library/RawDoFmt
exec.library/ReleaseSemaphore
exec.library/ReleaseSemaphoreList
exec.library/RemDevice
exec.library/RemHead
exec.library/RemIntServer
exec.library/RemLibrary
exec.library/Remove
exec.library/RemPort
exec.library/RemResource
exec.library/RemSemaphore
exec.library/RemTail
exec.library/RemTask
exec.library/ReplyMsg
exec.library/SendIO
exec.library/SetExcept
exec.library/SetFunction
exec.library/SetIntVector
exec.library/SetSignal
exec.library/SetSR
exec.library/SetTaskPri
exec.library/Signal
exec.library/SumKickData
exec.library/SumLibrary
exec.library/SuperState
exec.library/TypeOfMem
exec.library/UserState
exec.library/Vacate
exec.library/Wait
exec.library/WaitIO
exec.library/WaitPort

exec.library/AbortIO                    exec.library/AbortIO

   NAME
    AbortIO - attempt to abort an in-progress I/O request

   SYNOPSIS
    error = AbortIO(iORequest)
    D0        A1
    BYTE AbortIO(struct IORequest *);

   FUNCTION
    Ask a device to abort a previously started IORequest.  This is done
    by calling the device's ABORTIO vector, with your given IORequest.


    AbortIO is a request that device that may or may not grant.  If
    successful, the device will stop processing the IORequest, and
    reply to it earlier than it would otherwise have done.

   NOTE
    AbortIO() does NOT remove the IORequest from your ReplyPort, OR
    wait for it to complete.  After an AbortIO() you must wait normally
    for the reply message before actually reusing the request [see
    WaitIO()].

    If a request has already completed when AbortIO() is called, no
    action is taken.

   EXAMPLE
        AbortIO(timer_request);
        WaitIO (timer_request);
        /* Message is free to be reused */

   RESULTS
    error - Depending on the device and the state of the request, it
        may not be possible to abort a given I/O request.  If for
        some reason the device cannot abort the request, it should
        return an error code in D0.

   INPUTS
    iORequest - pointer to an I/O request block.

   RESULTS
    error - zero if successful, else an error is returned

   SEE ALSO
    WaitIO, DoIO, SendIO, CheckIO


exec.library/AddDevice                      exec.library/AddDevice

   NAME
    AddDevice -- add a device to the system

   SYNOPSIS
    AddDevice(device)
          A1
    void AddDevice(struct Device *);

   FUNCTION
    This function adds a new device to the system device list, making
    it available to other programs.  The device must be ready to be
    opened at this time.

   INPUTS
    device - pointer to a properly initialized device node

   SEE ALSO
    RemDevice, OpenDevice, CloseDevice, MakeLibrary


exec.library/AddHead                    exec.library/AddHead

   NAME
    AddHead -- insert node at the head of a list

   SYNOPSIS
    AddHead(list, node)
        A0    A1
    void AddHead(struct List *, struct Node *)

   FUNCTION
    Add a node to the head of a doubly linked list. Assembly
    programmers may prefer to use the ADDHEAD macro from
    "exec/lists.i".

   WARNING
    This function does not arbitrate for access to the list.  The
    calling task must be the owner of the involved list.

   INPUTS
    list - a pointer to the target list header
    node - the node to insert at head

   SEE ALSO
    AddTail, Enqueue, Insert, Remove, RemHead, RemTail


exec.library/AddIntServer               exec.library/AddIntServer

   NAME
    AddIntServer -- add an interrupt server to the system

   SYNOPSIS
    AddIntServer(intNum, interrupt)
             D0-0:4  A1
    void AddIntServer(ULONG, struct Interrupt *);

   FUNCTION
    This function adds a new interrupt server to a given server chain.
    The node is located on the chain in a priority dependent position.
    If this is the first server on a particular chain, interrupts will
    be enabled for that chain.

    Each link in the chain will be called in priority order until the
    chain ends or one of the servers returns with the 68000's Z
    condition code clear (indicating non-zero).  Servers on the chain
    should return with the Z bit clear if the interrupt was
    specifically for that server, and no one else.    VERTB servers
    should always return Z set.

    Servers are called with the following register conventions:

        D0 - scratch
        D1 - scratch

        A0 - scratch
        A1 - server is_Data pointer (scratch)

        A5 - jump vector register (scratch)
        A6 - scratch

        all other registers - must be preserved

   INPUTS
    intNum - the Portia interrupt bit number (0 through 14). Processor
         level seven interrupts (NMI) are encoded as intNum 15.
         The PORTS, VERTB, COPER and EXTER and NMI interrupts are
         set up as server chains.
    interrupt - pointer to an interrupt server node

   SEE ALSO
    RemIntServer, SetIntVector, hardware/intbits.h

   BUGS
    The graphics library's VBLANK server incorrectly assumes that
    address register A0 will contain a pointer to the custom chips.  If
    you add a server at a priority of 10 or greater, you must
    compensate for this by providing the expected value ($DFF000).

exec.library/AddLibrary exec.library/AddLibrary

   NAME
    AddLibrary -- add a library to the system

   SYNOPSIS
    AddLibrary(library)
           A1
    void AddLibrary(struct Library *);

   FUNCTION
    This function adds a new library to the system, making it available
    to other programs.  The library should be ready to be opened at
    this time.  It will be added to the system library name list, and
    the checksum on the library entries will be calculated.

   INPUTS
    library - pointer to a properly initialized library structure

   SEE ALSO
    RemLibrary, CloseLibrary, OpenLibrary, MakeLibrary


exec.library/AddMemList                  exec.library/AddMemList

   NAME
    AddMemList - add memory to the system free pool

   SYNOPSIS
    AddMemList( size, attributes, pri, base, name )
                     D0      D1        D2   A0    A1
    void AddMemList(ULONG, ULONG, LONG, APTR, char *);

   FUNCTION
    Add a new region of memory to the system free pool.  The first few
    bytes will be used to hold the MemHeader structure.  The remainder
    will be made available to the rest of the world.

   INPUTS
    size - the size (in bytes) of the memory area
    attributes - the attributes word that the memory pool will have
    pri  - the priority for this memory.  CHIP memory has a pri of -10,
           16 bit expansion memory has a priority of 0.  The higher the
           priority, the closer to the head of the memory list it will
           be placed.
    base - the base of the new memory area
    name - the name that will be used in the memory header, or NULL
           if no name is to be provided.  This name is not copied, so it
           must remain valid for as long as the memory header is in the
           system.

   SEE ALSO
    AllocMem, exec/memory.h


exec.library/AddPort                    exec.library/AddPort

   NAME
    AddPort -- add a public message port to the system

   SYNOPSIS
    AddPort(port)
        A1
    void AddPort(struct MsgPort *);

   FUNCTION
    This function attaches a message port structure to the system's
    public message port list, where it can be found by the FindPort()
    function.  The name and priority fields of the port structure must
    be initialized prior to calling this function.    If the user does
    not require the priority field, it should be initialized to zero.

    Ports that will NOT be searched for by name (with the FindPort()
    function) do not need to be added to the system list, though
    adding the port can be handy for debugging.  If the port WILL be
    searched for, the priority field should be at least 1 (so it will
    be before other less used ports).

    Once a port has been added to the naming list, you must be careful
    to remove the port from the list (via RemPort) before deallocating
    its memory.

   NOTE
    A point of confusion is that clearing a MsgPort structure to all
    zeros is not enough to prepare it for use.  As mentioned in the
    Exec chapter of the ROM Kernel Manual, the List for the MsgPort
    must be initialized.  This is automatically handled by AddPort(),
    and amiga.lib/CreatePort.  This initialization can be done manually
    with amiga.lib/NewList or the assembly NEWLIST macro.

   INPUTS
    port - pointer to a message port

   SEE ALSO
    RemPort, FindPort, amiga.lib/CreatePort, amiga.lib/NewList


exec.library/AddResource                exec.library/AddResource

   NAME
    AddResource -- add a resource to the system

   SYNOPSIS
    AddResource(resource)
            A1
    void AddResource(APTR);

   FUNCTION
    This function adds a new resource to the system and makes it
    available to other users.  The resource must be ready to be called
    at this time.

    Resources currently have no system-imposed structure, other than
    starting with a standard Exec node or Library structure.

   INPUTS
    resource - pointer an initialized resource node

   SEE ALSO
    RemResource, OpenResource


exec.library/AddSemaphore               exec.library/AddSemaphore

   NAME
    AddSemaphore -- add a signal semaphore to the system

   SYNOPSIS
    AddSemaphore(signalSemaphore)
             A1
    void AddSemaphore(struct SignalSemaphore *);

   FUNCTION
    This function attaches a signal semaphore structure to the system's
    public signal semaphore list.  The name and priority fields of the
    semaphore structure must be initialized prior to calling this
    function.  If you do not want to let others rendezvous with this
    semaphore, use InitSemaphore() instead.

    If a semaphore has been added to the naming list, you must be
    careful to remove the semaphore from the list (via RemSemaphore)
    before deallocating its memory.

    Semaphores that are linked together in an allocation list (which
    ObtainSemaphoreList() would use) may not be added to the system
    naming list, because the facilities use the link field of the
    signal semaphore in incompatible ways

   INPUTS
       signalSemaphore -- an signal semaphore structure

   BUGS
    Does not work in Kickstart V33 and V34.  Instead use this code:

        #include "exec/execbase.h"
        ...
        void AddSemaphore(s)
        struct SignalSemaphore *s;
        {
        InitSemaphore(s);
        Forbid();
        Enqueue(&SysBase->SemaphoreList,s);
        Permit();
        }

   SEE ALSO
    RemSemaphore, FindSemaphore, InitSemaphore

exec.library/AddTail                    exec.library/AddTail

   NAME
    AddTail -- append node to tail of a list

   SYNOPSIS
    AddTail(list, node)
                A0    A1
    void AddTail(struct List *, struct Node *);

   FUNCTION
    Add a node to the tail of a doubly linked list.  Assembly
    programmers may prefer to use the ADDTAIL macro from
    "exec/lists.i".

   WARNING
    This function does not arbitrate for access to the list.  The
    calling task must be the owner of the involved list.

   INPUTS
    list - a pointer to the target list header
    node - a pointer to the node to insert at tail of the list

   SEE ALSO
    AddHead, Enqueue, Insert, Remove, RemHead, RemTail


exec.library/AddTask                    exec.library/AddTask

   NAME
    AddTask -- add a task to the system

   SYNOPSIS
    AddTask(task, initialPC, finalPC)
        A1    A2     A3
    void AddTask(struct Task *, APTR, APTR);

   FUNCTION
    Add a task to the system.  A reschedule will be run; the task with
    the highest priority in the system will start to execute (this may
    or may not be the new task).

    Certain fields of the task control block must be initialized and a
    stack allocated prior to calling this function.  The absolute
    smallest stack that is allowable is something in the range of 100
    bytes, but in general the stack size is dependent on what
    subsystems are called. In general 256 bytes is sufficient if only
    Exec is called, and 4K will do if anything in the system is called.

    This function will temporarily use space from the new task's stack
    for the task's initial set of registers.  This space is allocated
    starting at the SPREG location specified in the task control block
    (not from SPUPPER).  This means that a task's stack may contain
    static data put there prior to its execution.  This is useful for
    providing initialized global variables or some tasks may want to
    use this space for passing the task its initial arguments.

    A task's initial registers are set to zero (except the PC).

    The TC_MEMENTRY field of the task structure may be extended by
    the user to hold additional MemLists (as returned by AllocEntry()).
    These will be automatically be deallocated at RemTask() time.
    If the code you have used to start the task has already added
    something to the MEMENTRY list, simply use AddHead to add your
    new MemLists in.  If no initialization has been done, a NewList will
    need to be performed.

   INPUTS
    task - pointer to the task control block
    initialPC - the initial entry point's address
    finalPC - the finalization code entry point's address.  If zero,
          the system will use a general finalizer. This pointer is
          placed on the stack as if it were the outermost return
          address.

   WARNING
    Tasks are a low-level building block, and are unable to call
    AmigaDOS, or any system routine that might call AmigaDOS.  See the
    AmigaDOS CreateProc() for information on Processes.

   SEE ALSO
    RemTask, FindTask, amiga.lib/CreateTask, dos/CreateProc,
    amiga.lib/NewList


exec.library/Alert                      exec.library/Alert

   NAME
    Alert -- alert the user of an error

   SYNOPSIS
    Alert(alertNum, parameters)
          D7    A5
    void Alert(ULONG, APTR);

   FUNCTION
    Alerts the user of a serious system problem.  This function will
    bring the system to a grinding halt, and do whatever is necessary
    to present the user with a message stating what happened.
    Interrupts are disabled, and an attempt to post the alert is made.
    If that fails, the system is reset.  When the system comes up
    again, Exec notices the cause of the failure and tries again to
    post the alert.

    If the Alert is a recoverable type, this call MAY return.

    This call may be made at any time, including interrupts.

   INPUT
    alertNum - a number indicating the particular alert
    parameters - currently points to the number that forms the
             second part of a "Guru meditation" message. Typically
             this is a pointer to the task that was active at the
             time of the problem.

   NOTE
    Much more needs to be said about this function and its implications.

   SEE ALSO
    exec/alerts.h

exec.library/AllocAbs                       exec.library/AllocAbs

   NAME
    AllocAbs -- allocate at a given location

   SYNOPSIS
    memoryBlock = AllocAbs(byteSize, location)
    D0               D0     A1
    void *AllocAbs(ULONG, APTR);

   FUNCTION
    This function attempts to allocate memory at a given absolute
    memory location.  Often this is used by boot-surviving entities
    such as recoverable ram-disks.    If the memory is already being
    used, or if there is not enough memory to satisfy the request,
    AllocAbs will return NULL.

    This block may not be exactly the same as the requested block
    because of rounding, but if the return value is non-zero, the block
    is guaranteed to contain the requested range.

   INPUTS
    byteSize - the size of the desired block in bytes
           This number is rounded up to the next larger
           block size for the actual allocation.
    location - the address where the memory MUST be.


   RESULT
    memoryBlock - a pointer to the newly allocated memory block, or
              NULL if failed.

   NOTE
    If the free list is corrupt, the system will panic with alert
    AN_MemCorrupt, $81000005.

   SEE ALSO
    AllocMem, FreeMem

exec.library/Allocate                       exec.library/Allocate

   NAME
    Allocate - allocate a block of memory

   SYNOPSIS
    memoryBlock=Allocate(MemHeader, byteSize)
    D0             A0     D0
    void *Allocate(struct MemHeader *, ULONG);

   FUNCTION
    This function is used to allocate blocks of memory from a given
    private free memory pool (as specified by a MemHeader and its
    memory chunk list).  Allocate will return the first free block that
    is greater than or equal to the requested size.

    All blocks, whether free or allocated, will be block aligned;
    hence, all allocation sizes are rounded up to the next block even
    value (e.g. the minimum allocation resolution is currently 8
    bytes).

    This function can be used to manage an application's internal data
    memory.  Note that no arbitration of the MemHeader and associated
    free chunk list is done.  You must be the owner before calling
    Allocate.

   INPUTS
    freeList - points to the memory list header
    byteSize - the size of the desired block in bytes

   RESULT
    memoryBlock - a pointer to the just allocated free block.
           If there are no free regions large enough to satisfy the
           request, return zero.

   EXAMPLE
    #include "exec/types.h"
    #include "exec/memory.h"
    void *AllocMem();
    #define BLOCKSIZE 4000L /* Or whatever you want */

    void main()
    {
    struct MemHeader *mh;
    struct MemChunk  *mc;
    APTR   block1;
    APTR   block2;

        /* Get the MemHeader needed to keep track of our new block */
        mh = (struct MemHeader *)
         AllocMem((long)sizeof(struct MemHeader), MEMF_CLEAR );
        if( !mh )
        exit(10);

        /* Get the actual block the above MemHeader will manage */
        mc = (struct MemChunk *)AllocMem( BLOCKSIZE, 0L );
        if( !mc )
        {
        FreeMem( mh, (long)sizeof(struct MemHeader) ); exit(10);
        }

        mh->mh_Node.ln_Type = NT_MEMORY;
        mh->mh_Node.ln_Name = "myname";
        mh->mh_First = mc;
        mh->mh_Lower = (APTR) mc;
        mh->mh_Upper = (APTR) ( BLOCKSIZE + (ULONG) mc );
        mh->mh_Free  = BLOCKSIZE;

        /* Set up first chunk in the freelist */
        mc->mc_Next  = NULL;
        mc->mc_Bytes = BLOCKSIZE;

        block1 = (APTR) Allocate( mh, 20L );
        block2 = (APTR) Allocate( mh, 314L );
        printf("mh=$%lx mc=$%lx\n",mh,mc);
        printf("Block1=$%lx, Block2=$%lx\n",block1,block2);

        FreeMem( mh, (long)sizeof(struct MemHeader) );
        FreeMem( mc, BLOCKSIZE );
    }

   NOTE
    If the free list is corrupt, the system will panic with alert
    AN_MemCorrupt, $81000005.

   SEE ALSO
    Deallocate

exec.library/AllocEntry                  exec.library/AllocEntry

   NAME
    AllocEntry -- allocate many regions of memory

   SYNOPSIS
    memList = AllocEntry(memList)
    D0             A0
    struct MemList *AllocEntry(struct MemList *);

   FUNCTION
    This routine takes a memList structure and allocates enough memory
    to hold the required memory as well as a MemList structure to keep
    track of it.

    These MemList structures may be linked together in a task control
    block to keep track of the total memory usage of this task. (See
    the description of TC_MEMENTRY under RemTask).

   INPUTS
    memList -- A MemList structure filled in with MemEntry structures.

   RESULTS
    memList -- A different MemList filled in with the actual memory
        allocated in the me_Addr field, and their sizes in me_Length.
        If enough memory cannot be obtained, then the requirements of
        the allocation that failed is returned and bit 31 is set.

   EXAMPLES
    The user wants five regions of 2, 4, 8, 16, and 32 bytes in size
    with requirements of MEMF_CLEAR, MEMF_PUBLIC, MEMF_CHIP!MEMF_CLEAR,
    MEMF_FAST!MEMF_CLEAR, and MEMF_PUBLIC!MEMF_CLEAR respectively.    The
    following code fragment would do that:

        MemListDecl:
        DS.B    LN_SIZE         * reserve space for list node
        DC.W    5            * number of entries
        DC.L    MEMF_CLEAR            * entry #0
        DC.L    2
        DC.L    MEMF_PUBLIC            * entry #1
        DC.L    4
        DC.L    MEMF_CHIP!MEMF_CLEAR        * entry #2
        DC.L    8
        DC.L    MEMF_FAST!MEMF_CLEAR        * entry #3
        DC.L    16
        DC.L    MEMF_PUBLIC!MEMF_CLEAR        * entry #4
        DC.L    32

        start:
        LEA.L    MemListDecl(PC),A0
        JSR    _LVOAllocEntry(a6)
        BCLR.L    #31,D0
        BEQ.S    success

        ------- Type of memory that we failed on is in D0

   BUGS
    If any one of the allocations fails, this function fails to back
    out fully.  This is fixed by the "SetPatch" program on V1.3
    Workbench disks.

   SEE ALSO
    exec/memory.h

exec.library/AllocMem                       exec.library/AllocMem

   NAME
    AllocMem -- allocate memory given certain requirements

   SYNOPSIS
    memoryBlock = AllocMem(byteSize, attributes)
    D0               D0     D1
    void *AllocMem(ULONG, ULONG);

   FUNCTION
    This is the memory allocator to be used by system code and
    applications.  It provides a means of specifying that the allocation
    should be made in a memory area accessible to the chips, or
    accessible to shared system code.

    Memory is allocated based on requirements and options.    Any
    "requirement" must be met by a memory allocation, any "option" will
    be applied to the block regardless.  AllocMem will try all memory
    spaces until one is found with the proper requirements and room for
    the memory request.

   INPUTS
    byteSize - the size of the desired block in bytes.  This number is
        rounded up to the next larger memory chunk size for the
        actual allocation.  The chunk size is guaranteed to be
        at least 8.


    attributes -
        requirements

        MEMF_CHIP:    Only certain parts of memory are reachable
                by the special chip sets' DMA circuitry.
                Anything that will use on-chip DMA *MUST*
                be in memory with this attribute. DMA
                includes screen memory, things that are
                blitted, audio blocks, sprites and
                trackdisk.device buffers.

        MEMF_FAST:    This is non-chip memory.  It is possible
                for the processor to get locked out of chip
                memory under certain conditions. If one
                cannot accept these delays, then one should
                use FAST memory (by default the system will
                allocate from FAST memory first anyway).

                This is rarely specified, since it would
                cause incompatibility with non-expanded
                machines.

        MEMF_PUBLIC:    Memory must not be mapped, swapped,
                or otherwise made non-addressable. ALL
                MEMORY THAT IS REFERENCED VIA INTERRUPTS
                AND/OR BY OTHER TASKS MUST BE EITHER PUBLIC
                OR LOCKED INTO MEMORY! This includes both
                code and data.

        options

        MEMF_CLEAR:    The memory will be initialized to all
                zeros.


   RESULT
    memoryBlock - a pointer to the newly allocated block. If there are
        no free regions large enough to satisfy the request (or if
        the amount of requested memory is invalid), return zero.

   WARNING
    The result of any memory allocate MUST be checked, and a viable
    error handling path taken.  ANY allocation may fail if memory has
    been filled.

   EXAMPLES
    AllocMem(321,MEMF_CHIP) - private chip memory
    AllocMem(25,MEMF_PUBLIC|MEMF_CLEAR) - a cleared "public" system
               structure that does not require chip memory.

   NOTE
    If the free list is corrupt, the system will panic with alert
    AN_MemCorrupt, $81000005.

    This function may not be called from interrupts.

   SEE ALSO
    FreeMem


exec.library/AllocSignal                exec.library/AllocSignal

   NAME
    AllocSignal -- allocate a signal bit

   SYNOPSIS
    signalNum = AllocSignal(signalNum)
    D0            D0
    BYTE AllocSignal(LONG);

   FUNCTION
    Allocate a signal bit from the current tasks' pool.  Either a
    particular bit, or the next free bit may be allocated.    The signal
    associated with the bit will be properly initialized (cleared).  At
    least 16 user signals are available per task.  Signals should be
    deallocated before the task exits.

    If the signal is already in use (or no free signals are available)
    a -1 is returned.

    This function can only be used by the currently running task.

   WARNING
    Signals may not be allocated or freed from exception handling code.

   INPUTS
    signalNum - the desired signal number {of 0..31} or -1 for no
            preference.

   RESULTS
    signalNum - the signal bit number allocated {0..31}. If no signals
            are available, this function returns -1.

   SEE ALSO
    FreeSignal


exec.library/AllocTrap                      exec.library/AllocTrap

   NAME
    AllocTrap -- allocate a processor trap vector

   SYNOPSIS
    trapNum = AllocTrap(trapNum)
    D0            D0
    LONG AllocTrap(LONG);

   FUNCTION
    Allocate a trap number from the current task's pool.  These trap
    numbers are those associated with the 68000 TRAP type instructions.
    Either a particular number, or the next free number may be
    allocated.

    If the trap is already in use (or no free traps are available) a -1
    is returned.

    This function only affects the currently running task.

    Traps are sent to the trap handler pointed at by tc_TrapCode.
    Unless changed by user code, this points to a standard trap
    handler.  The stack frame of the exception handler will be:

        0(SP) = Exception vector number.  This will be in the
            range of 32 to 47 (corresponding to the
            Trap #1...Trap #15 instructions).
        4(SP) = 68000/68010/68020/68030, etc. exception frame

    tc_TrapData is not used.


   WARNING
    Traps may not be allocated or freed from exception handling code.
    You are not allowed to write to the exception table yourself.  In
    fact, on some machines you will have trouble finding it - the VBR
    register may be used to remap its location.

   INPUTS
    trapNum - the desired trap number {of 0..15} or -1
          for no preference.

   RESULTS
    trapNum - the trap number allocated {of 0..15}.  If no traps are
          available, this function returns -1.    Instructions of the
          form "Trap #trapNum" will be sent to the task's trap
          handler.

   SEE ALSO
    FreeTrap


exec.library/AttemptSemaphore               exec.library/AttemptSemaphore

   NAME
    AttemptSemaphore -- try to obtain without blocking

   SYNOPSIS
    success = AttemptSemaphore(signalSemaphore)
    D0               A0
    LONG AttemptSemaphore(struct SignalSemaphore *);

   FUNCTION
    This call is similar to ObtainSemaphore(), except that it will not
    block if the semaphore could not be locked.

   INPUT
       signalSemaphore -- an initialized signal semaphore structure

   RESULT
    success -- TRUE if the semaphore was locked, false if some
        other task already possessed the semaphore.

   SEE ALSO
    ObtainSemaphore(), ReleaseSemaphore(), exec/semaphores.h


exec.library/AvailMem                       exec.library/AvailMem

   NAME
    AvailMem -- memory available given certain requirements

   SYNOPSIS
    size = AvailMem(attributes)
    D0        D1
    ULONG AvailMem(ULONG);

   FUNCTION
    This function returns the amount of free memory given certain
    attributes.

    To find out what the largest block of a particular type is, add
    MEMF_LARGEST into the requirements argument.

   WARNING
    Due to the effect of multitasking, the value returned may not
    actually be the amount of free memory available at that instant.

   INPUTS
    requirements - a requirements mask as specified in AllocMem.  Any
               of the AllocMem bits are valid, as is MEMF_LARGEST
               which returns the size of the largest block matching
               the requirements.

   RESULT
    size - total free space remaining (or the largest free block).

   EXAMPLE
    AvailMem(MEMF_CHIP|MEMF_LARGEST);
    /* return size of largest available chip memory chunk */

   SEE ALSO
    exec/memory.h


exec.library/Cause                      exec.library/Cause

   NAME
       Cause -- cause a software interrupt

   SYNOPSIS
       Cause(interrupt)
         A1
       void Cause(struct Interrupt *);

   FUNCTION
    This function causes a software interrupt to occur.  If it is
    called from user mode (and processor level 0), the software
    interrupt will preempt the current task.  This call is often used
    by high-level hardware interrupts to defer medium-length processing
    down to a lower interrupt level.  Note that a software interrupt is
    still a real interrupt, and must obey the same restrictions on what
    system routines it may call.

    Currently only 5 software interrupt priorities are implemented:
    -32, -16, 0, +16, and +32.  Priorities in between are truncated,
    values outside the -32/+32 range are not allowed.

   NOTE
    When setting up the Interrupt structure, set the node type to
    NT_INTERRUPT.

   IMPLEMENTATION
    1> Checks if the node type is NT_SOFTINT.  If so does nothing since
       the softint is already pending.  No nest count is maintained.
    2> Sets the node type to NT_SOFTINT.
    3> Links into one of the 5 priority queues.
    4> Pokes the hardware interrupt bit used for softints.

    The node type returns to NT_INTERRUPT after removal from the list.

   INPUTS
    interrupt - pointer to a properly initialized interrupt node

exec.library/CheckIO                    exec.library/CheckIO

   NAME
    CheckIO -- get the status of an IORequest

   SYNOPSIS
    result = CheckIO(iORequest)
    D0         A1
    BOOL CheckIO(struct IORequest *);

   FUNCTION
    This function determines the current state of an I/O request and
    returns FALSE if the I/O has not yet completed.  This function
    effectively hides the internals of the I/O completion mechanism.

    CheckIO will NOT remove the returned IORequest from the reply port.
    This is best performed with WaitIO(). If the request has already
    completed, WaitIO() will return quickly. Use of the Remove()
    function is dangerous, since other tasks may still be adding things
    to your message port; a Disable() would be required.

    This function should NOT be used to busy loop (looping until IO is
    complete).  WaitIO() is provided for that purpose.

   INPUTS
    iORequest - pointer to an I/O request block

   RESULTS
    result - null if I/O is still in progress.  Otherwise
         D0 points to the IORequest block.

   SEE ALSO
    DoIO, SendIO, WaitIO, AbortIO


exec.library/CloseDevice                exec.library/CloseDevice

   NAME
    CloseDevice -- conclude access to a device

   SYNOPSIS
    CloseDevice(iORequest)
            A1
    void CloseDevice(struct IORequest *);

   FUNCTION
    This function informs the device that access to a device/unit
    previously opened has been concluded.  The device may perform
    certain house-cleaning operations.

    The user must ensure that all outstanding IORequests have been
    returned before closing the device.  The AbortIO function can kill
    any stragglers.

    After a close, the I/O request structure is free to be reused.

   INPUTS
    iORequest - pointer to an I/O request structure

   SEE ALSO
    OpenDevice

exec.library/CloseLibrary               exec.library/CloseLibrary

   NAME
    CloseLibrary -- conclude access to a library

   SYNOPSIS
    CloseLibrary(library)
             A1
    void CloseLibrary(struct Library *);

   FUNCTION
    This function informs the system that access to the given library
    has been concluded.  The user must not reference the library or any
    routine in the library after this close.

   INPUTS
    library - pointer to a library node

   SEE ALSO
    OpenLibrary


exec.library/CopyMem                    exec.library/CopyMem

   NAME
    CopyMem - general purpose memory copy routine

   SYNOPSIS
    CopyMem( source, dest, size )
         A0     A1    D0
    void CopyMem(APTR,APTR,ULONG);

   FUNCTION
    CopyMem is a general purpose, fast memory copy routine.  It can
    deal with arbitrary lengths, with its pointers on arbitrary
    alignments.  It attempts to optimize larger copies with more
    efficient copies, it uses byte copies for small moves, parts of
    larger copies, or the entire copy if the source and destination are
    misaligned with respect to each other.

    Arbitrary overlapping copies are not supported.

    The internal implementation of this routine will change from
    system to system, and may be implemented via hardware DMA.

   INPUTS
    source - a pointer to the source data region
    dest - a pointer to the destination data region
    size - the size (in bytes) of the memory area

   SEE ALSO
    CopyMemQuick

exec.library/CopyMemQuick               exec.library/CopyMemQuick

   NAME
    CopyMemQuick - optimized memory copy routine

   SYNOPSIS
    CopyMemQuick( source, dest, size )
              A0      A1    D0
    void CopyMem(ULONG *,ULONG *,ULONG);

   FUNCTION
    CopyMemQuick is a highly optimized memory copy routine, with
    restrictions on the size and alignment of its arguments. Both the
    source and destination pointers must be longword aligned.  In
    addition, the size must be an integral number of longwords (e.g.
    the size must be evenly divisible by four).

    Arbitrary overlapping copies are not supported.

    The internal implementation of this routine will change from system
    to system, and may be implemented via hardware DMA.

   INPUTS
    source - a pointer to the source data region, long aligned
    dest - a pointer to the destination data region, long aligned
    size - the size (in bytes) of the memory area

   SEE ALSO
    CopyMem

exec.library/Deallocate                  exec.library/Deallocate

   NAME
    Deallocate -- deallocate a block of memory

   SYNOPSIS
    Deallocate(MemHeader, memoryBlock, byteSize)
           A0          A1       D0
    void Deallocate(struct MemHeader *,APTR,ULONG);

   FUNCTION
    This function deallocates memory by returning it to the appropriate
    private free memory pool.  This function can be used to free an
    entire block allocated with the above function, or it can be used
    to free a sub-block of a previously allocated block.  Sub-blocks
    must be an even multiple of the memory chunk size (currently 8
    bytes).

    This function can even be used to add a new free region to an
    existing MemHeader, however the extent pointers in the MemHeader
    will no longer be valid.

    If memoryBlock is not on a block boundary (MEM_BLOCKSIZE) then it
    will be rounded down in a manner compatible with Allocate().  Note
    that this will work correctly with all the memory allocation
    routines, but may cause surprises if one is freeing only part of a
    region.  The size of the block will be rounded up, so the freed
    block will fill to an even memory block boundary.

   INPUTS
    freeList - points to the free list
    memoryBlock - memory block to return
    byteSize - the size of the desired block in bytes. If NULL, nothing
           happens.

   SEE ALSO
    Allocate


exec.library/Debug                      exec.library/Debug

   NAME
    Debug -- run the system debugger

   SYNOPSIS
    void Debug(0L);
           D0
   FUNCTION
    This function calls the system debugger.  By default this debugger
    is "ROM-WACK".  Other debuggers are encouraged to take over this
    entry point (via SetFunction()) so that when an application calls
    Debug(), the alternative debugger will get control.  Currently a
    zero is passed to allow future expansion.

   NOTE
    The Debug() call may be made when the system is in a questionable
    state; if you have a SetFunction() patch, make few assumptions, be
    prepared for Supervisor mode, and be aware of differences in the
    Motorola stack frames on the 68000,'10,'20, and '30.

   SEE ALSO
    SetFunction
    your favorite debugger's manual
    the ROM-WACK chapter of the ROM Kernel Manual

exec.library/Disable                    exec.library/Disable

    NAME
    Disable -- disable interrupt processing.

    SYNOPSIS
    Disable();

    void Disable(void);

    FUNCTION
    Prevents interrupts from being handled by the system, until a
    matching Enable() is executed.  Disable() implies Forbid().

    RESULTS
    All interrupt processing is deferred until the task executing makes
    a call to Enable() or is placed in a wait state.  Normal task
    rescheduling does not occur while interrupts are disabled.  In order
    to restore normal interrupt processing, the programmer must execute
    exactly one call to Enable() for every call to Disable().

    IMPORTANT REMINDER:

    It is important to remember that there is a danger in using
    disabled sections.  Disabling interrupts for more than ~250
    microseconds will prevent vital system functions (especially serial
    I/0) from operating in a normal fashion.

    Think twice before using Disable(), then think once more.
    After all that, think again.  With enough thought, the need
    for a Disable() can often be eliminated.
    Do not use a macro for Disable(), insist on the real thing.

    This call may be made from interrupts, it will have the effect
    of locking out all higher-level interrupts (lower-level interrupts
    are automatically disabled by the CPU).

    WARNING
    In the event of a task entering a Wait after disabling interrupts,
    the system "breaks" the forbidden state and runs normally until the
    task which called Forbid() is rescheduled.

    If caution is not taken, this can cause subtle bugs, since any
    device or DOS call will (in effect) cause your task to wait.

   SEE ALSO
    Forbid, Permit, Enable

exec.library/DoIO                       exec.library/DoIO

   NAME
    DoIO -- perform an I/O command and wait for completion

   SYNOPSIS
    error = DoIO(iORequest)
    D0         A1
    BYTE DoIO(struct IORequest *);

   FUNCTION
    This function requests a device driver to perform the I/O command
    specified in the I/O request.  This function will always wait until
    the I/O request is fully complete.

   IMPLEMENTATION
    This function first tries to complete the IO via the "Quick I/O"
    mechanism.  The io_Flags field is always set to IOF_QUICK (0x01)
    before the internal device call.

   INPUTS
    iORequest - pointer to an IORequest initialized by OpenDevice()

   RESULTS
    error - a sign-extended copy of the io_Error field of the
        IORequest.  Most device commands require that the error
        return be checked.

   SEE ALSO
    SendIO, CheckIO, WaitIO, AbortIO, amiga.lib/BeginIO


exec.library/Enable                     exec.library/Enable

   NAME
    Enable -- permit system interrupts to resume.

   SYNOPSIS
    Enable();

    void Enable(void);

   FUNCTION
    Allow system interrupts to again occur normally, after a matching
    Disable() has been executed.

   RESULTS
    Interrupt processing is restored to normal operation. The
    programmer must execute exactly one call to Enable() for every call
    to Disable().

   SEE ALSO
    Forbid, Permit, Disable


exec.library/Enqueue                    exec.library/Enqueue

   NAME
    Enqueue -- insert or append node to a system queue

   SYNOPSIS
    Enqueue(list, node)
        A0    A1
    void Enqueue(struct List *, struct Node *);

   FUNCTION
    Insert or append a node into a system queue.  The insert is
    performed based on the node priority -- it will keep the list
    properly sorted.  New nodes will be inserted in front of the first
    node with a lower priority.   Hence a FIFO queue for nodes of equal
    priority

   WARNING
    This function does not arbitrate for access to the list.  The
    calling task must be the owner of the involved list.

   INPUTS
    list - a pointer to the system queue header
    node - the node to enqueue

   SEE ALSO
    AddHead, AddTail, Insert, Remove, RemHead, RemTail


exec.library/FindName                       exec.library/FindName

   NAME
    FindName -- find a system list node with a given name

   SYNOPSIS
    node = FindName(start, name)
    D0        A0     A1
    struct Node *FindName(struct List *,char *);

   FUNCTION
    Traverse a system list until a node with the given name is found.
    To find multiple occurrences of a string, this function may be
    called with a node starting point.

    No arbitration is done for access to the list!    If multiple tasks
    access the same list, an arbitration mechanism such as
    SignalSemaphores must be used.

   INPUTS
    start - a list header or a list node to start the search
        (if node, this one is skipped)
    name - a pointer to a name string terminated with null

   RESULTS
    node - a pointer to the node with the same name else
        zero to indicate that the string was not found.


exec.library/FindPort                      exec.library/FindPort

   NAME
    FindPort -- find a given system message port

   SYNOPSIS
    port = FindPort(name)
    D0        A1
    struct MsgPort *FindPort(char *);

   FUNCTION
    This function will search the system message port list for a port
    with the given name.  The first port matching this name will be
    returned.  No arbitration of the port list is done.  This function
    MUST be protected with A Forbid()/Permit() pair!

   EXAMPLE
    #include "exec/types.h"
    struct MsgPort *FindPort();

    ULONG SafePutToPort(message, portname)
    struct Message *message;
    char           *portname;
    {
    struct MsgPort *port;

        Forbid();
        port = FindPort(portname);
        if (port)
            PutMsg(port,message);
        Permit();
        return((ULONG)port); /* If zero, the port has gone away */
    }

   INPUT
    name - name of the port to find

   RETURN
    port - a pointer to the message port, or zero if
        not found.


exec.library/FindResident               exec.library/FindResident

   NAME
    FindResident - find a resident module by name

   SYNOPSIS
    resident = FindResident(name)
    D0            A1
    struct Resident *FindResident(char *);

   FUNCTION
    Find the resident tag with the given name.  If found return a
    pointer to the resident tag structure, else return zero.

    Resident modules are used by the system to pull all its parts
    together at startup.  Resident tags are also found in disk based
    devices and libraries.

   INPUTS
    name - pointer to name string

    RESULT
    resident - pointer to the resident tag structure or
        zero if none found.

    SEE ALSO
    exec/resident.h

exec.library/FindSemaphore              exec.library/FindSemaphore

   NAME
    FindSemaphore -- find a given system signal semaphore

   SYNOPSIS
    signalSemaphore = FindSemaphore(name)
    D0                        A1
    struct SignalSemaphore *FindSemaphore(char *);

   FUNCTION
    This function will search the system signal semaphore list for a
    semaphore with the given name.    The first semaphore matching this
    name will be returned.

   INPUT
    name - name of the semaphore to find

   BUGS
    This routine does not arbitrate for access to the semaphore list,
    surround the call with a Forbid()/Permit() pair.

   RETURN
    semaphore - a pointer to the signal semaphore, or zero if not
            found.


exec.library/FindTask                       exec.library/FindTask

   NAME
    FindTask -- find a task with the given name or find oneself

   SYNOPSIS
    task = FindTask(name)
    D0        A1
    struct Task *FindTask(char *);

   FUNCTION
    This function will check all task queues for a task with the given
    name, and return a pointer to its task control block.  If a NULL
    name pointer is given a pointer to the current task will be
    returned.

    Finding oneself with a NULL for the name is very quick.  Finding a
    task by name is very system expensive, and will disable interrupts
    for a long time.

   INPUT
    name - pointer to a name string

   RESULT
    task - pointer to the task (or Process)


exec.library/Forbid                     exec.library/Forbid

    NAME
    Forbid -- forbid task rescheduling.

    SYNOPSIS
    Forbid()

    void Forbid(void);

    FUNCTION
    Prevents other tasks from being scheduled to run by the dispatcher,
    until a matching Permit() is executed, or this task is scheduled to
    Wait.  Interrupts are NOT disabled.

    RESULTS
    The current task will not be rescheduled as long as it is ready to
    run.  In the event that the current task enters a wait state, other
    tasks may be scheduled.  Upon return from the wait state, the original
    task will continue to run without disturbing the Forbid().

    Calls to Forbid() nest. In order to restore normal task rescheduling,
    the programmer must execute exactly one call to Permit() for every
    call to Forbid().

    WARNING
    In the event of a task entering a Wait after a Forbid(), the system
    "breaks" the forbidden state and runs normally until the task which
    called Forbid() is rescheduled.
    If caution is not taken, this can cause subtle bugs, since any
    device or DOS call will (in effect) cause your task to wait.

    Forbid() is not useful or safe from within an interrupt routine
    (Since interrupts are always higher priority than tasks, and
    since interrupts are allowed interrupt a Forbid()).

    SEE ALSO
    Permit, Disable


exec.library/FreeEntry                      exec.library/FreeEntry

   NAME
    FreeEntry -- free many regions of memory

   SYNOPSIS
    FreeEntry(memList)
          A0
    void FreeEntry(struct MemList *);

   FUNCTION
    This routine takes a memList structure (as returned by AllocEntry)
    and frees all the entries.

   INPUTS
    memList -- pointer to structure filled in with MemEntry
           structures

   SEE ALSO
    AllocEntry

exec.library/FreeMem                    exec.library/FreeMem

   NAME
    FreeMem -- deallocate with knowledge

   SYNOPSIS
    FreeMem(memoryBlock, byteSize)
        A1         D0
    void FreeMem(void *,ULONG);

   FUNCTION
    Free a region of memory, returning it to the system pool from which
    it came.  Freeing partial blocks back into the system pool is
    unwise.

   NOTE
    If a block of memory is freed twice, the system will GURU. The
    Alert is AN_FreeTwice ($81000009). Future versions may add more
    sanity checks to the memory lists.

   INPUTS
    memoryBlock - memory block to free
        If the memoryBlock previously returned by an allocation
        routine.
    byteSize - the size of the block in bytes

   SEE ALSO
    AllocMem


exec.library/FreeSignal                  exec.library/FreeSignal

   NAME
    FreeSignal -- free a signal bit

   SYNOPSIS
    FreeSignal(signalNum)
           D0
    FreeSignal(ULONG);

   FUNCTION
    This function frees a previously allocated signal bit for reuse.
    This call must be performed while running in the same task in which
    the signal was allocated.

   WARNING
    Signals may not be allocated or freed from exception handling code.

   INPUTS
    signalNum - the signal number to free {0..31}


exec.library/FreeTrap                       exec.library/FreeTrap

   NAME
    FreeTrap -- free a processor trap

   SYNOPSIS
    FreeTrap(trapNum)
         D0
    void FreeTrap(ULONG);

   FUNCTION
    This function frees a previously allocated trap number for reuse.
    This call must be performed while running in the same task in which
    the trap was allocated.

   WARNING
    Traps may not be allocated or freed from exception handling code.

   INPUTS
    trapNum - the trap number to free {of 0..15}


exec.library/GetCC                      exec.library/GetCC

   NAME
    GetCC -- get condition codes in a 68010 compatible way.

   SYNOPSIS
    conditions = GetCC()
      D0
    UWORD = GetCC(void);

   FUNCTION
    The 68000 processor has a "MOVE SR,<ea>" instruction which gets a
    copy of the processor condition codes.

    On the 68010,20 and 30 CPUs, "MOVE SR,<ea>" is privileged.  User
    code will trap if it is attempted.  These processors need to use
    the "MOVE CCR,<ea>" instruction instead.

    This function provides a means of obtaining the CPU condition codes
    in a manner that will make upgrades transparent.  This function is
    very short and quick.

   RESULTS
    conditions - the 680XX condition codes

exec.library/GetMsg                     exec.library/GetMsg

   NAME
    GetMsg -- get next message from a message port

   SYNOPSIS
    message = GetMsg(port)
    D0         A0
    struct Message *GetMsg(struct MsgPort *);

   FUNCTION
    This function receives a message from a given message port. It
    provides a fast, non-copying message receiving mechanism. The
    received message is removed from the message port.

    This function will not wait.  If a message is not present this
    function will return zero.  If a program must wait for a message,
    it can Wait() on the signal specified for the port or use the
    WaitPort() function.  There can only be one task waiting for any
    given port.

    Getting a message does not imply to the sender that the message is
    free to be reused by the sender.  When the receiver is finished
    with the message, it may ReplyMsg() it back to the sender.


    Getting a signal does NOT always imply a message is ready.  More
    than one message may arrive per signal, and signals may show up
    without messages.  Typically you must loop to GetMsg() until it
    returns zero, then Wait() or WaitPort().

   INPUT
    port - a pointer to the receiver message port

   RESULT
    message - a pointer to the first message available.  If
          there are no messages, return zero.
          Callers must be prepared for zero at any time.

   SEE ALSO
    PutMsg, ReplyMsg, WaitPort, Wait, exec/ports.h


exec.library/InitCode                       exec.library/InitCode

   NAME
    InitCode - initialize resident code modules

   SYNOPSIS
    InitCode(startClass, version)
         D0         D1
    void InitCode(ULONG,ULONG);

   FUNCTION
    Initialize all resident modules with the given startClass and with
    versions equal or greater than that specified. Modules are
    initialized in a prioritized order.

    Resident modules are used by the system to pull all its parts
    together at startup.  Resident tags are also found in disk based
    devices and libraries.

   INPUTS
    startClass - the class of code to be initialized: coldstart,
             coolstart, warmstart, ...
    version    - a major version number

    SEE ALSO
    exec/resident.h


exec.library/InitResident               exec.library/InitResident

   NAME
    InitResident - initialize resident module

   SYNOPSIS
    InitResident(resident, segList)
             A1        D1
    void InitResident(struct Resident *,BPTR);

   FUNCTION
    Initialize a module (these are also called "ROM-tags").  This includes
    interpreting the fields of the ROM-tag, and calling the initialization
    hooks.

    An automatic method of library/device base and vector table
    initialization is also provided through the use of a such a ROM-tag
    (Resident) structure.  In this case, the initial code hunk of the
    library or device should contain "MOVEQ #-1,d0; RTS;".  Following
    that must be an initialized Resident structure including RTF_AUTOINIT
    in rt_Flags, and an rt_Init pointer which points to four longwords as
    follows:

        - Size of your library/device base structure including initial
          Library or Device structure.
        - Pointer to a longword table of standard, then library
          specific function offsets, terminated with -1L.
        - Pointer to data table in exec/InitStruct format for
          initialization of Library or Device structure.
        - Pointer to library initialization routine, which will receive
          library/device base in d0, segment in a0, and must return
          non-zero to link the library/device into the device/library
          list.

   SEE ALSO
    exec/resident.h

exec.library/InitSemaphore              exec.library/InitSemaphore

   NAME
    InitSemaphore -- initialize a signal semaphore

   SYNOPSIS
    InitSemaphore(signalSemaphore)
              A0
    void InitSemaphore(struct SignalSemaphore *);

   FUNCTION
    This function initializes a signal semaphore and prepares it for
    use.  It does not allocate anything, but does initialize list
    pointers and the semaphore counters.

    Semaphores are often used to protect critical data structures
    or hardware that can only be accessed by one task at a time.
    After initialization, the address of the SignalSemaphore may be
    made available to any number of tasks.  Typically a task will
    try to ObtainSemaphore(), passing this address in.  If no other
    task owns the semaphore, then the call will lock and return
    quickly.  If more tasks try to ObtainSemaphore(), they will
    be put to sleep.  When the owner of the semaphore releases
    it, the next waiter in turn will be woken up.

    Semaphores are often preferable to the old-style Forbid()/Permit()
    type arbitration.  With Forbid()/Permit() *all* other tasks are
    prevented from running.  With semaphores, only those tasks that
    need access to whatever the semaphore protects are subject
    to waiting.

   INPUT
    signalSemaphore -- an uninitialized signal semaphore structure

   SEE ALSO
    ObtainSemaphore(), AttemptSemaphore(), ReleaseSemaphore()
    exec/semaphores.h


exec.library/InitStruct                  exec.library/InitStruct

   NAME
    InitStruct - initialize memory from a table

   SYNOPSIS
    InitStruct(initTable, memory, size);
           A1          A2      D0
    void InitStruct(struct InitStruct *, APTR, ULONG);

   FUNCTION
    Clear a memory area except those words whose data and offset values
    are provided in the initialization table.  Typically only assembly
    programs take advantage of this, and only with the macros defined
    in "exec/initializers.i".

    The initialization table has byte commands to

         |a    ||byte|    |given||byte|          |once        |
    load |count||word| into |next ||rptr| offset, |repetitively |
            |long|

    Not all combinations are supported.  The offset, when specified, is
    relative to the memory pointer provided (Memory), and is initially
    zero.  The initialization data (InitTable) contains byte commands
    whose 8 bits are interpreted as follows:

    ddssnnnn
        dd    the destination type (and size):
        00  next destination, nnnn is count
        01  next destination, nnnn is repeat
        10  destination offset is next byte, nnnn is count
        11  destination offset is next rptr, nnnn is count
        ss    the size and location of the source:
        00  long, from the next two aligned words
        01  word, from the next aligned word
        10  byte, from the next byte
        11  ERROR - will cause an ALERT (see below)
      nnnn    the count or repeat:
         count  the (number+1) of source items to copy
        repeat  the source is copied (number+1) times.

    initTable commands are always read from the next even byte. Given
    destination offsets are always relative to memory (A2).

    The command 00000000 ends the InitTable stream: use 00010001 if you
    really want to copy one longword.

    24 bit APTR not supported for 68020 compatibility -- use long.

   INPUTS
    initTable - the beginning of the commands and data to init
        Memory with.  Must be on an even boundary unless only
        byte initialization is done.
    memory - the beginning of the memory to initialize.  Must be
        on an even boundary if size is specified.
    size - the size of memory, which is used to clear it before
        initializing it via the initTable.  If Size is zero,
        memory is not cleared before initializing.  Size is
        rounded down to the nearest even number before use.

    SEE ALSO
    exec/initializers.i

exec.library/Insert                     exec.library/Insert

   NAME
    Insert -- insert a node into a list

   SYNOPSIS
    Insert(list, node, listNode)
           A0    A1    A2
    void Insert(struct List *, struct Node *, struct Node *);

   FUNCTION
    Insert a node into a doubly linked list AFTER a given node
    position.  Insertion at the head of a list is possible by passing a
    zero value for listNode, though the AddHead function is slightly
    faster for that special case.

   WARNING
    This function does not arbitrate for access to the list.  The
    calling task must be the owner of the involved list.

   INPUTS
    list - a pointer to the target list header
    node - the node to insert
    listNode - the node after which to insert

    SEE ALSO
    AddHead, AddTail, Enqueue, RemHead, Remove, RemTail


exec.library/MakeFunctions              exec.library/MakeFunctions

   NAME
    MakeFunctions -- construct a function jump table

   SYNOPSIS
    tableSize = MakeFunctions(target, functionArray, funcDispBase)
    D0              A0      A1         A2
    ULONG MakeFunctions(APTR,APTR,APTR);

   FUNCTION
    This function constructs a function jump table of the type used by
    resources, libraries, and devices.  It allows the table to be built
    anywhere in memory, and can be used both for initialization and
    replacement. This function also supports function pointer
    compression by expanding relative displacements into absolute
    pointers.

   INPUT
    destination - the target address for the high memory end of the
        function jump table.  Typically this will be the library
        base pointer.

    functionArray - pointer to an array of function pointers or
        function displacements.  If funcDispBase is zero, the array
        is assumed to contain absolute pointers to functions. If
        funcDispBase is not zero, then the array is assumed to
        contain word displacements to functions.  In both cases,
        the array is terminated by a -1 (of the same size as the
        actual entry.

    funcDispBase - pointer to the base about which all function
        displacements are relative.  If zero, then the function
        array contains absolute pointers.

   RESULT
    tableSize - size of the new table in bytes.

   SEE ALSO
    exec/MakeLibrary

exec.library/MakeLibrary                exec.library/MakeLibrary

   NAME
    MakeLibrary -- construct a library

   SYNOPSIS
    library = MakeLibrary(vectors, structure, init, dSize, segList)
    D0              A0       A1      A2    D0     D1
    struct Library *MakeLibrary
                  (APTR,struct InitStruct *,APTR,ULONG,BPTR);

   FUNCTION
    This function is used for constructing a library vector and data
    area.  The same call is used to make devices.  Space for the library
    is allocated from the system's free memory pool. The size fields of
    the library are filled.  The data portion of the library is
    initialized.  init may point to a library specific entry point,
    or NULL if no call is to be made.

   INPUTS
    vectors - pointer to an array of function pointers or function
        displacements.    If the first word of the array is -1, then
        the array contains relative word displacements (based off
        of vectors); otherwise, the array contains absolute
        function pointers. The vector list is terminated by a -1
        (of the same size as the pointers).

    structure - points to an "InitStruct" data region.  If NULL,
        then it will not be used.

    init -    an entry point that will be called before adding the
        library to the system.    If null, it will not be called. When
        it is called, it will be called with the libAddr in D0 and
        the segList parameter in A0. The result of the init function
        will be the result returned by MakeLibrary.
        A Forbid()/Permit() pair surrounds this call.

    dSize - the size of the library data area, including the
        standard library node data.

       segList - pointer to an AmigaDOS SegList (segment list).
         This is passed to a library's init code, and is used later
         for removing the library from memory.

   RESULT
    library - the reference address of the library.  This is the
          address used in references to the library, not the
          beginning of the memory area allocated.  If the library
          vector table require more system memory than is
          available, this function will return NULL.

   SEE ALSO
    InitStruct, InitResident, exec/initializers.i

exec.library/ObtainSemaphore            exec.library/ObtainSemaphore

   NAME
    ObtainSemaphore -- gain exclusive access to a semaphore

   SYNOPSIS
    ObtainSemaphore(signalSemaphore)
            A0
    void ObtainSemaphore(struct SignalSemaphore *);

   FUNCTION
    Signal semaphores are used to gain exclusive access to an object.
    ObtainSemaphore is the call used to gain this access.  If another
    user currently has the semaphore locked the call will block until
    the object is available.

    If the current task already has locked the semaphore and attempts to
    lock it again the call will still succeed.  A "nesting count" is
    incremented each time the current owning task of the semaphore calls
    ObtainSemaphore().  This counter is decremented each time
    ReleaseSemaphore() is called.  When the counter returns to zero the
    semaphore is actually released, and the next waiting task is called.

    A queue of waiting tasks is maintained on the stacks of the waiting
    tasks.    Each will be called in turn as soon as the current task
    releases the semaphore.

    Signal Semaphores are different than Procure()/Vacate() semaphores.
    The former requires less CPU time, especially if the semaphore is
    not currently locked.  They require very little set up and user
    thought.  The latter flavor of semaphore make no assumptions about
    how they are used -- they are completely general.  Unfortunately
    they are not as efficient as signal semaphores, and require the
    locker to have done some setup before doing the call.

   INPUT
       signalSemaphore -- an initialized signal semaphore structure

   SEE ALSO
    InitSemaphore(), ReleaseSemaphore()
    AttemptSemaphore(), ObtainSemaphoreList()


exec.library/ObtainSemaphoreList        exec.library/ObtainSemaphoreList

   NAME
    ObtainSemaphoreList -- get a list of semaphores.

   SYNOPSIS
    ObtainSemaphoreList(list)
                A0
    void ObtainSemaphoreList(struct List *);

   FUNCTION
    Signal semaphores may be linked together into a list. This routine
    takes a list of these semaphores and attempts to lock all of them at
    once. This call is preferable to applying ObtainSemaphore() to each
    element in the list because it attempts to lock all the elements
    simultaneously, and won't deadlock if someone is attempting to lock
    in some other order.

    This routine assumes that only one task at a time will attempt to
    lock the entire list of semaphores.  In other words, there needs to
    be a higher level lock (perhaps another signal semaphore...) that is
    used before someone attempts to lock the semaphore list via
    ObtainSemaphoreList().

    Note that deadlocks may result if this call is used AND someone
    attempts to use ObtainSemaphore() to lock more than one semaphore on
    the list.  If you wish to lock more than semaphore (but not all of
    them) then you should obtain the higher level lock (see above)

   INPUT
       list -- a list of signal semaphores

   SEE ALSO
    ObtainSemaphore(), ReleaseSemaphore(), ReleaseSemaphoreList()


exec.library/OldOpenLibrary             exec.library/OldOpenLibrary

   NAME
    OldOpenLibrary -- obsolete OpenLibrary

   SYNOPSIS
    library = OldOpenLibrary(libName)
    D0             A1
    struct Library *OldOpenLibrary(APTR);

   FUNCTION
    The 1.0 release of the Amiga system had an incorrect version of
    OpenLibrary that did not check the version number during the
    library open.  This obsolete function is provided so that object
    code compiled using a 1.0 system will still run.

    This exactly the same as "OpenLibrary(libName,0L);"

   INPUTS
    libName - the name of the library to open

   RESULTS
    library - a library pointer for a successful open, else zero

   SEE ALSO
    CloseLibrary

exec.library/OpenDevice                  exec.library/OpenDevice

   NAME
    OpenDevice -- gain access to a device

   SYNOPSIS
    error = OpenDevice(devName, unitNumber, iORequest, flags)
    D0           A0        D0        A1       D1
    BYTE OpenDevice(char *,ULONG,struct IORequest *,ULONG);

   FUNCTION
    This function opens the named device/unit and initializes the given
    I/O request block.  Specific documentation on opening procedures
    may come with certain devices.

    The device may exist in memory, or on disk; this is transparent to
    the OpenDevice caller.

    A full path name for the device name is legitimate.  For example
    "test:devs/fred.device".  This allows the use of custom devices
    without requiring the user to copy the device into the system's
    DEVS: directory.

   NOTE
    All calls to OpenDevice should have matching calls to CloseDevice!

   INPUTS
    devName - requested device name

    unitNumber - the unit number to open on that device.  The format of
        the unit number is device specific.  If the device does
        not have separate units, send a zero.

    iORequest - the I/O request block to be returned with
        appropriate fields initialized.

    flags - additional driver specific information.  This is sometimes
        used to request opening a device with exclusive access.

   RESULTS
    error - Returns a sign-extended copy of the io_Error field
        of the IORequest.  Zero if successful, else an error code
        is returned.

   BUGS
    AmigaDOS file names are not case sensitive, but Exec lists are.  If
    the library name is specified in a different case than it exists on
    disk, unexpected results may occur.

    Tasks should not be allowed to make OpenDevice calls that will
    cause the device to be loaded from disk (since tasks are not
    allowed to make AmigaDOS requests).

   SEE ALSO
    CloseDevice, DoIO, SendIO, CheckIO, AbortIO, WaitIO

exec.library/OpenLibrary                exec.library/OpenLibrary

   NAME
    OpenLibrary -- gain access to a library

   SYNOPSIS
    library = OpenLibrary(libName, version)
    D0              A1       D0
    struct Library *OpenLibrary(char *,ULONG);

   FUNCTION
    This function returns a pointer to a library that was previously
    installed into the system.  If the requested library is exists, and
    if the library version is greater than or equal to the requested
    version, then the open will succeed.

    The device may exist in memory, or on disk; this is transparent to
    the OpenDevice caller.    Since this call may in turn call AmigaDOS,
    only Processes are allowed to call it.

    A full path name for the library name is legitimate.  For example
    "wp:libs/wp.library".  This allows the use of custom libraries
    without requiring the user to copy the library into the system's
    LIBS: directory.

   NOTE
    All calls to OpenLibrary should have matching calls to CloseLibrary!

   INPUTS
    libName - the name of the library to open

    version - the version of the library required.

   RESULTS
    library - a library pointer for a successful open, else zero

   BUGS
    AmigaDOS file names are not case sensitive, but Exec lists are. If
    the library name is specified in a different case than it exists on
    disk, unexpected results may occur.

    Tasks should not be allowed to make OpenLibrary calls that will
    cause the library to be loaded from disk (since tasks are not
    allowed to make AmigaDOS requests).

   SEE ALSO
    CloseLibrary

exec.library/OpenResource               exec.library/OpenResource

   NAME
    OpenResource -- gain access to a resource

   SYNOPSIS
    resource = OpenResource(resName)
    D0            A1
    APTR OpenResource(char *);

   FUNCTION
    This function returns a pointer to a resource that was previously
    installed into the system.

    There is no CloseResource() function.

   INPUTS
       resName - the name of the resource requested.

   RESULTS
    resource - if successful, a resource pointer, else NULL

exec.library/Permit                      exec.library/Permit

    NAME
    Permit -- permit task rescheduling.

    SYNOPSIS
    Permit()

    void Permit(void);

    FUNCTION
    Allow other tasks to be scheduled to run by the dispatcher, after a
    matching Forbid() has been executed.

    RESULTS
    Other tasks will be rescheduled as they are ready to run. In order
    to restore normal task rescheduling, the programmer must execute
    exactly one call to Permit() for every call to Forbid().

    SEE ALSO
    Forbid, Disable, Enable


exec.library/Procure                     exec.library/Procure

   NAME
    Procure -- bid for a message lock (semaphore)

   SYNOPSIS
    result = Procure(semaphore, bidMessage)
    D0         A0        A1
    BYTE Procure(struct Semaphore *, struct Message *);

   FUNCTION
    This function is used to obtain a message based semaphore lock.  If
    the lock is immediate, Procure() returns a true result, and the
    bidMessage is not used.   If the semaphore is already locked,
    Procure() returns false, and the task must wait for the bidMessage
    to arrive at its reply port.

    Straight "Semaphores" use the message system.  They are therefore
    queueable, and users may wait on several of them at the same time.
    This makes them more powerful than "Signal Semaphores"

   INPUT
    semaphore - a semaphore message port.  This port is used to queue
    all pending lockers.  This port should be initialized with the
    PA_IGNORE option, as the MP_SigTask field is used for a pointer to
    the current locker message (not a task). New semaphore ports must
    also have the SM_BIDS word initialized to -1.  If the semaphore is
    public, it should be named, its priority set, and the added with
    AddPort. Message port priority is often used for anti-deadlock
    locking conventions.

   RESULT
    result - true when the semaphore is free.  In such cases no waiting
    needs to be done.  If false, then the task should wait at its
    bidMessage reply port.

   BUGS
    Procure() and Vacate() do not have proven reliability.

   SEE ALSO
    Vacate()


exec.library/PutMsg                      exec.library/PutMsg

   NAME
    PutMsg -- put a message to a message port

   SYNOPSIS
    PutMsg(port, message)
           A0    A1
    void PutMsg(struct MsgPort *, struct Message *);

   FUNCTION
    This function attaches a message to a given message port. It
    provides a fast, non-copying message sending mechanism.

    Messages can be attached to only one port at a time.  The message
    body can be of any size or form.  Because messages are not copied,
    cooperating tasks share the same message memory.  The sender task
    should not recycle the message until it has been replied by the
    receiver.  Of course this depends on the message handling conventions
    setup by the involved tasks.  If the ReplyPort field is non-zero,
    when the message is replied by the receiver, it will be sent back to
    that port.

    Any one of the following actions can be set to occur when a message
    is put:

        1. no special action
        2. signal a given task (specified by MP_SIGTASK)
        3. cause a software interrupt (specified by MP_SIGTASK)

    The action is selected depending on the value found in the MP_FLAGS
    of the destination port.

   IMPLEMENTATION
    1.  Sets the LN_TYPE field to "NT_MESSAGE".
    2.  Attaches the message to the destination port.
    3.  Performs the specified arrival action at the destination.

   INPUT
    port - pointer to a message port
    message - pointer to a message

   SEE ALSO
    GetMsg, ReplyMsg, exec/ports.h

exec.library/RawDoFmt                       exec.library/RawDoFmt

   NAME
    RawDoFmt -- format data into a character stream.

   SYNOPSIS
    RawDoFmt(FormatString, DataStream, PutChProc, PutChData);
         A0           A1       A2          A3
    void(char *,APTR,void (*)(),APTR);

   FUNCTION
    perform "C"-language-like formatting of a data stream, outputting
    the result a character at a time.  Where % formatting commands are
    found in the FormatString, they will be replaced with the
    corresponding element in the DataStream.  %% must be used in the
    string if a % is desired in the output.

   INPUTS
    FormatString - a "C"-language-like null terminated format string,
    with the following supported % options:

         %[flags][width.limit][length]type

        flags  - only one allowed. '-' specifies left justification.
        width  - field width.  If the first character is a '0', the
             field will be padded with leading 0's.
          .    - must follow the field width, if specified
        limit  - maximum number of characters to output from a string.
             (only valid for %s).
        length - size of input data defaults to WORD, 'l' changes this
             to long.
        type   - supported types are:
            d - decimal
            x - hexadecimal
            s - string
            c - character

    DataStream - a stream of data that is interpreted according to
             the format string.  Often this is a pointer into
             the task's stack.
    PutChProc  - the procedure to call with each character to be
             output, called as:

        PutChProc(Char,  PutChData);
              D0-0:8 A3

        the procedure is called with a null Char at the end of
        the format string.

    PutChData - a value that is passed through to the PutChProc
            procedure.    This is untouched by RawDoFmt, and may be
            modified by the PutChProc.

   EXAMPLE
;
; Simple version of the C "sprintf" function.  Assumes C-style
; stack-based function conventions.
;
;   long eyecount;
;   eyecount=2;
;   sprintf(string,"%s have %ld eyes.","Fish",eyecount);
;
; would produce "Fish have 2 eyes." in the string buffer.
;
        XDEF _sprintf
_sprintf:    ; ( string, format, {values} )
        movem.l a2/a3/a6,-(sp)

        move.l    5*4(sp),a3       ;Get the output string pointer
        move.l    6*4(sp),a0       ;Get the FormatString pointer
        lea.l    7*4(sp),a1       ;Get the pointer to the DataStream
        lea.l    stuffChar(pc),a2
        move.l    _AbsExecBase,a6
        jsr    _LVORawDoFmt(a6)

        movem.l (sp)+,a2/a3/a6
        rts

;------ PutChProc function used by RawDoFmt -----------
stuffChar:    move.b    d0,(a3)+            ;Put data to output string
        rts

   WARNING
    This is the only Amiga ROM function that accepts word inputs. If
    your compiler defaults to longs, you will need to add a "l" to your
    % specification.  This can get strange for characters, which must
    look like "%lc".

   SEE ALSO
    Documentation on the C language "printf" call in any C language
    reference book.

exec.library/ReleaseSemaphore               exec.library/ReleaseSemaphore

   NAME
    ReleaseSemaphore -- make signal semaphore available to others

   SYNOPSIS
    ReleaseSemaphore(signalSemaphore)
             A0
    void ReleaseSemaphore(struct SignalSemaphore *);

   FUNCTION
    ReleaseSemaphore() is the inverse of ObtainSemaphore(). It makes
    the semaphore lockable to other users.    If tasks are waiting for
    the semaphore and this this task is done with the semaphore then
    the next waiting task is signalled.

    Each ObtainSemaphore() call must be balanced by exactly one
    ReleaseSemaphore() call.  This is because there is a nesting count
    maintained in the semaphore of the number of times that the current
    task has locked the semaphore. The semaphore is not released to
    other tasks until the number of releases matches the number of
    obtains.

    Needless to say, havoc breaks out if the task releases more times
    than it has obtained.

   INPUT
       signalSemaphore -- an initialized signal semaphore structure

   SEE ALSO
    ObtainSemaphore(), AttemptSemaphore()

exec.library/ReleaseSemaphoreList       exec.library/ReleaseSemaphoreList

   NAME
    ReleaseSemaphoreList -- make a list of semaphores available

   SYNOPSIS
    ReleaseSemaphoreList(list)
                 A0
    void ReleaseSemaphoreList(struct List *);

   FUNCTION
    ReleaseSemaphoreList() is the inverse of ObtainSemaphoreList(). It
    releases each element in the semaphore list.

    Needless to say, havoc breaks out if the task releases more times
    than it has obtained.

   INPUT
       list -- a list of signal semaphores

   SEE ALSO
    ObtainSemaphore(), ReleaseSemaphore(), ObtainSemaphoreList()
    AttemptSemaphore()


exec.library/RemDevice                      exec.library/RemDevice

   NAME
    RemDevice -- remove a device from the system

   SYNOPSIS
    void RemDevice(device)
               A1
    void RemDevice(struct Device *);

   FUNCTION
    This function calls the device's EXPUNGE vector, which requests
    that a device delete itself.  The device may refuse to do this if
    it is busy or currently open. This is not typically called by user
    code.

    There are certain, limited circumstances where it may be
    appropriate to attempt to specifically flush a certain device.
    Example:

     /* Attempts to flush the named device out of memory. */
     #include "exec/types.h"
     #include "exec/execbase.h"

     void FlushDevice(name)
     char  *name;
     {
     struct Device *result;

        Forbid();
        if(result=(struct Device *)FindName(&SysBase->DeviceList,name))
        RemDevice(result);
        Permit();
     }

   INPUTS
    device - pointer to a device node

   SEE ALSO
    AddLibrary

exec.library/RemHead                    exec.library/RemHead

   NAME
    RemHead -- remove the head node from a list

   SYNOPSIS
    node = RemHead(list)
    D0           A0
    struct Node *RemHead(struct List *);

   FUNCTION
    Get a pointer to the head node and remove it from the list.
    Assembly programmers may prefer to use the REMHEAD macro from
    "exec/lists.i".

   WARNING
    This function does not arbitrate for access to the list.  The
    calling task must be the owner of the involved list.

   INPUTS
    list - a pointer to the target list header

   RESULT
    node - the node removed or zero when empty list

   SEE ALSO
    AddHead, AddTail, Enqueue, Insert, Remove, RemTail

exec.library/RemIntServer               exec.library/RemIntServer

   NAME
    RemIntServer -- remove an interrupt server

   SYNOPSIS
    RemIntServer(intNum, interrupt)
             D0      A1
    void RemIntServer(ULONG,struct Interrupt *);

   FUNCTION
    This function removes an interrupt server node from the given
    server chain.

    If this server was the last one on this chain, interrupts for this
    chain are disabled.

   INPUTS
    intNum - the Portia interrupt bit (0..14)
    interrupt - pointer to an interrupt server node

   SEE ALSO
    AddIntServer, hardware/intbits.h


exec.library/RemLibrary                   exec.library/RemLibrary

   NAME
    RemLibrary -- remove a library from the system

   SYNOPSIS
    void RemLibrary(library)
           A1
    void RemLibrary(struct Library *);

   FUNCTION
    This function calls the library's EXPUNGE vector, which requests
    that a library delete itself.  The library may refuse to do this if
    it is busy or currently open. This is not typically called by user
    code.

    There are certain, limited circumstances where it may be
    appropriate to attempt to specifically flush a certain Library.
    Example:

     /* Attempts to flush the named library out of memory. */
     #include "exec/types.h"
     #include "exec/execbase.h"

     void FlushLibrary(name)
     char  *name;
     {
     struct Library *result;

        Forbid();
        if(result=(struct Library *)FindName(&SysBase->LibList,name))
        RemLibrary(result);
        Permit();
     }

   INPUTS
    library - pointer to a library node structure

exec.library/Remove                     exec.library/Remove

   NAME
    Remove -- remove a node from a list

   SYNOPSIS
    Remove(node)
           A1
    void Remove(struct Node *);

   FUNCTION
    Remove a node from whatever list it is in.  Nodes that are not part
    of a list must not be Removed!  Assembly programmers may prefer to
    use the REMOVE macro from "exec/lists.i".

   WARNING
    This function does not arbitrate for access to the list.  The
    calling task must be the owner of the involved list.

   INPUTS
    node - the node to remove

   SEE ALSO
    AddHead, AddTail, Enqueue, Insert, RemHead, RemTail

exec.library/RemPort                    exec.library/RemPort

   NAME
    RemPort -- remove a message port from the system

   SYNOPSIS
    RemPort(port)
        A1
    void RemPort(struct MsgPort *);

   FUNCTION
    This function removes a message port structure from the system's
    message port list.  Subsequent attempts to rendezvous by name with
    this port will fail.

   INPUTS
    port - pointer to a message port

   SEE ALSO
    AddPort, FindPort

exec.library/RemResource                exec.library/RemResource

   NAME
    RemResource -- remove a resource from the system

   SYNOPSIS
    RemResource(resource)
           A1
    void RemResource(APTR);

   FUNCTION
    This function removes an existing resource from the system resource
    list.

   INPUTS
    resource - pointer to a resource node

   SEE ALSO
    AddResource

exec.library/RemSemaphore               exec.library/RemSemaphore

   NAME
    RemSemaphore -- remove a signal semaphore from the system

   SYNOPSIS
    RemSemaphore(signalSemaphore)
             A1
    void RemSemaphore(struct SignalSemaphore *);

   FUNCTION
    This function removes a signal semaphore structure from the
    system's signal semaphore list.  Subsequent attempts to
    rendezvous by name with this semaphore will fail.

   INPUTS
       signalSemaphore -- an initialized signal semaphore structure

   SEE ALSO
    AddSemaphore, FindSemaphore


exec.library/RemTail                    exec.library/RemTail

   NAME
    RemTail -- remove the tail node from a list

   SYNOPSIS
    node = RemTail(list)
    D0           A0
    struct Node *RemTail(struct List *);

   FUNCTION
    Remove the last node from a list, and return a pointer to it. If
    the list is empty, return zero. Assembly programmers may prefer to
    use the REMTAIL macro from "exec/lists.i".

   WARNING
    This function does not arbitrate for access to the list.  The
    calling task must be the owner of the involved list.

   INPUTS
    list - a pointer to the target list header

   RESULT
    node - the node removed or zero when empty list

   SEE ALSO
    AddHead, AddTail, Enqueue, Insert, Remove, RemHead, RemTail

exec.library/RemTask                    exec.library/RemTask

   NAME
    RemTask -- remove a task from the system

   SYNOPSIS
    RemTask(task)
        A1
    void RemTask(struct Task *);

   FUNCTION
    This function removes a task from the system.  Deallocation of
    resources should have been performed prior to calling this
    function.  Removing some other task is very dangerous.    Generally
    is is best to arrange for tasks to call RemTask(0L) on themselves.

    RemTask will automagically free any memory lists attached to the
    task's TC_MEMENTRY list.

   INPUTS
    task - pointer to the task node representing the task to be
           removed.  A zero value indicates self removal, and will
           cause the next ready task to begin execution.

   SEE ALSO
    AddTask, exec/AllocEntry, amiga.lib/DeleteTask

exec.library/ReplyMsg                       exec.library/ReplyMsg

   NAME
    ReplyMsg -- put a message to its reply port

   SYNOPSIS
    ReplyMsg(message)
         A1
    void ReplyMsg(struct Message *);

   FUNCTION
    This function sends a message to its reply port.  This is usually
    done when the receiver of a message has finished and wants to
    return it to the sender (so that it can be re-used or deallocated,
    whatever).

    This call may be made from interrupts.

   INPUT
    message - a pointer to the message

   IMPLEMENTATION
    1> Places "NT_REPLYMSG" into LN_TYPE.
    2> Puts the message to the port specified by MN_REPLYPORT
       If there is no replyport, sets LN_TYPE to "NT_FREEMSG".

   SEE ALSO
    GetMsg, PutMsg, exec/ports.h

exec.library/SendIO                     exec.library/SendIO

   NAME
    SendIO -- initiate an I/O command

   SYNOPSIS
    SendIO(iORequest)
           A1
    void SendIO(struct IORequest *);

   FUNCTION
    This function requests the device driver start processing the given
    I/O request.  The device will return control without waiting for
    the I/O to complete.

    The io_Flags field of the IORequest will be set to zero before the
    request is sent.

   INPUTS
    iORequest - pointer to an I/O request, or a device specific
            extended IORequest.

   SEE ALSO
    DoIO, CheckIO, WaitIO, AbortIO

exec.library/SetExcept                      exec.library/SetExcept

   NAME
    SetExcept -- define certain signals to cause exceptions

   SYNOPSIS
    oldSignals = SetExcept(newSignals, signalMask)
    D0               D0       D1
    ULONG SetExcept(ULONG,ULONG);

   FUNCTION
    This function defines which of the task's signals will cause a
    private task exception.  When any of the signals occurs the task's
    exception handler will be dispatched.  If the signal occurred prior
    to calling SetExcept, the exception will happen immediately.

    The user function pointed to by the task's tc_ExceptCode gets
    called as:

        newExcptSet = <exceptCode>(signals, exceptData),SysBase
        D0                   D0    A1        A6

        signals - The set of signals that caused this exception.  These
        Signals have been disabled from the current set of signals
        that can cause an exception.

        exceptData - A copy of the task structure tc_ExceptData field.

        newExcptSet - The set of signals in NewExceptSet will be re-
        enabled for exception generation.  Usually this will be the
        same as the Signals that caused the exception.

    All registers are preserved by the system before the call.


   INPUTS
    newSignals - the new values for the signals specified in
        signalMask.
    signalMask - the set of signals to be effected

   RESULTS
    oldSignals - the prior exception signals

   EXAMPLE
    Get the current state of all exception signals:
        SetExcept(0,0)
    Change a few exception signals:
        SetExcept($1374,$1074)

   SEE ALSO
    Signal, SetSignal

exec.library/SetFunction                exec.library/SetFunction

   NAME
    SetFunction -- change a function vector in a library

   SYNOPSIS
    oldFunc = SetFunction(library, funcOffset, funcEntry)
    D0              A1       A0.W       D0
    APTR SetFunction(struct Library *,LONG,APTR);

   FUNCTION
    SetFunction is a functional way of changing where vectors in a
    library point.    They are changed in such a way that the
    checksumming process will never falsely declare a library to be
    invalid.

   NOTE
    SetFunction cannot be used on non-standard libraries like
    dos.library.  Here you must manually Forbid(), preserve all 6
    original bytes, set the new vector, SumLibrary(), then Permit().

   INPUTS
    library    - a pointer to the library to be changed
    funcOffset - the offset of the function to be replaced
    funcEntry  - pointer to new function

   RESULTS
    oldFunc    - pointer to the old function that was just replaced

exec.library/SetIntVector                  exec.library/SetIntVector

   NAME
    SetIntVector -- set a system interrupt vector

   SYNOPSIS
    oldInterrupt = SetIntVector(intNumber, interrupt)
    D0                D0-0:4     A1
    struct Interrupt *SetIntVector(ULONG, struct Interrupt *);

   FUNCTION
    This function provides a mechanism for setting the system interrupt
    vectors.  These are non-sharable, setting something here
    disconnects the old handler.

    Both the code and data pointers of the vector are set to the new
    values.  A pointer to the old interrupt structure is returned. When
    the system calls the specified interrupt code the registers are
    setup as follows:

        D0 - scratch
        D1 - scratch (on entry: active portia
              interrupts -> equals INTENA & INTREQ)

        A0 - scratch (on entry: pointer to base of custom chips
              for fast indexing)
        A1 - scratch (on entry: interrupt's is_Data pointer)

        A5 - jump vector register (scratch on call)
        A6 - Exec library base pointer (scratch on call)

        all other registers - must be preserved

   INPUTS
    intNum - the Portia interrupt bit number (0..14)
    interrupt - a pointer to an Interrupt structure containing
        the handler's entry point and data segment pointer. It is a
        good idea to give the node a name so that other users may
        identify who currently has control of the interrupt.

   RESULT
    A pointer to the prior interrupt node which had control
    of this interrupt.

   SEE ALSO
    SetIntHandler, exec/interrupts.h, exec/hardware.h


exec.library/SetSignal                       exec.library/SetSignal

   NAME
    SetSignal -- define the state of this task's signals

   SYNOPSIS
    oldSignals = SetSignal(newSignals, signalMask)
    D0               D0       D1
    ULONG SetSignal(ULONG,ULONG);

   FUNCTION
    This function defines the states of the task's signals.
    Setting the state of signals is considered dangerous.
    Reading the state of signals is safe.

   INPUTS
    newSignals - the new values for the signals specified in
             signalSet.
    signalMask - the set of signals to be affected

   RESULTS
    oldSignals - the prior values for all signals

   EXAMPLES
    Get the current state of all signals:
        SetSignal(0,0);
    Clear all signals:
        SetSignal(0,0xFFFFFFFFL);
    Clear the CTRL-C signal:
        SetSignal(0,SIGBREAKF_CTRL_C);


    Check if the CTRL-C signal was pressed:

        #include "libraries/dos.h"

        if(SetSignal(0L,0L) & SIGBREAKF_CTRL_C)
        printf("CTRL-C pressed!\n");

   SEE ALSO
    Signal, Wait


exec.library/SetSR                      exec.library/SetSR

   NAME
    SetSR -- get and/or set processor status register

   SYNOPSIS
    oldSR = SetSR(newSR, mask)
    D0          D0     D1
    ULONG SetSR(ULONG, ULONG);

   FUNCTION
    This function provides a means of modifying the CPU status register
    in a "safe" way (well, how safe can a function like this be
    anyway?).  This function will only affect the status register bits
    specified in the mask parameter.  The prior content of the entire
    status register is returned.

   INPUTS
    newSR - new values for bits specified in the mask.
        All other bits are not effected.
    mask - bits to be changed

   RESULTS
    oldSR - the entire status register before new bits

   EXAMPLES
    To get the current SR:
        currentSR = SetSR(0,0);
    To change the processor interrupt level to 3:
        oldSR = SetSR($0300,$0700);
    Set processor interrupts back to prior level:
        SetSR(oldSR,$0700);

exec.library/SetTaskPri                  exec.library/SetTaskPri

   NAME
    SetTaskPri -- get and set the priority of a task

   SYNOPSIS
    oldPriority = SetTaskPri(task, priority)
    D0-0:8             A1    D0-0:8
    BYTE SetTaskPri(struct Task *,LONG);

   FUNCTION
    This function changes the priority of a task regardless of its
    state.    The old priority of the task is returned.  A reschedule is
    performed, and a context switch may result.

    To change the priority of the currently running task, pass the
    result of FindTask(0); as the task pointer.

   INPUTS
    task - task to be affected
    priority - the new priority for the task

   RESULT
    oldPriority - the tasks previous priority


exec.library/Signal                     exec.library/Signal

   NAME
    Signal -- signal a task

   SYNOPSIS
    Signal(task, signals)
           A1    D0
    void Signal(struct Task *,ULONG);

   FUNCTION
    This function signals a task with the given signals.  If the task
    is currently waiting for one or more of these signals, it will be
    made ready and a reschedule will occur. If the task is not waiting
    for any of these signals, the signals will be posted to the task
    for possible later use. A signal may be sent to a task regardless
    of whether its running, ready, or waiting.

    This function is considered "low level".  Its main purpose is to
    support multiple higher level functions like PutMsg.

    This function is safe to call from interrupts.

   INPUT
    task - the task to be signalled
    signals - the signals to be sent

   SEE ALSO
    Wait, SetSignal

exec.library/SumKickData                exec.library/SumKickData

   NAME
    SumKickData -- compute the checksum for the Kickstart delta list

   SYNOPSIS
    void SumKickData(void)

   FUNCTION
    The Amiga system has some ROM (or Kickstart) resident code that
    provides the basic functions for the machine.  This code is
    unchangeable by the system software.  This routine is part of a
    support system to modify parts of the ROM.

    The ROM code is linked together at run time via ROM-tags (also known
    as Resident structures, defined in exec/resident.h).  These tags tell
    Exec's low level boot code what subsystems exist in which regions of
    memory.  The current list of ROM-tags is contained in the ResModules
    field of ExecBase.  By default this list contains any ROM-tags found
    in the address ranges $FC0000-$FFFFFF and $F00000-$F7FFFF.

    There is also a facility to selectively add or replace modules to the
    ROM-tag list.  These modules can exist in RAM, and the memory they
    occupy will be deleted from the memory free list during the boot
    process.  SumKickData() plays an important role in this run-time
    modification of the ROM-tag array.

    Three variables in ExecBase are used in changing the ROM-tag array:
    KickMemPtr, KickTagPtr, and KickCheckSum. KickMemPtr points to a
    linked list of MemEntry structures. The memory that these MemEntry
    structures reference will be allocated (via AllocAbs) at boot time.
    The MemEntry structure itself must also be in the list.

    KickTagPtr points to a long-word array of the same format as the
    ResModules array.  The array has a series of pointers to ROM-tag
    structures.  The array is either null terminated, or will have an
    entry with the most significant bit (bit 31) set.  The most
    significant bit being set says that this is a link to another
    long-word array of ROM-tag entries.  This new array's address can be
    found by clearing bit 31.

    KickCheckSum has the result of SumKickData().  It is the checksum of
    both the KickMemPtr structure and the KickTagPtr arrays.  If the
    checksum does not compute correctly then both KickMemPtr and
    KickTagPtr will be ignored.

    If all the memory referenced by KickMemPtr can't be allocated then
    KickTagPtr will be ignored.

    There is one more important caveat about adding ROM-tags. All this
    ROM-tag magic is run very early on in the system -- before expansion
    memory is added to the system. Therefore any memory in this
    additional ROM-tag area must be addressable at this time. This means
    that your ROM-tag code, MemEntry structures, and resident arrays
    cannot be in expansion memory.  There are two regions of memory that
    are acceptable:  one is chip memory, and the other is "Ranger" memory
    (memory in the range between $C00000-$D80000).

    Remember that changing an existing ROM-tag entry falls into the
    "heavy magic" category -- be very careful when doing it.  The odd are
    that you will blow yourself out of the water.

   NOTE
    SumKickData was introduced in the 1.2 release

   SEE ALSO
    InitResident, FindResident

exec.library/SumLibrary                  exec.library/SumLibrary

   NAME
    SumLibrary -- compute and check the checksum on a library

   SYNOPSIS
    SumLibrary(library)
           A1
    void SumLibrary(struct Library *);

   FUNCTION
    SumLibrary computes a new checksum on a library.  It can also be
    used to check an old checksum.    If an old checksum does not match,
    and the library has not been marked as changed, then the system
    will call Alert().

    This call could also be periodically made by some future
    system-checking task.

   INPUTS
    library - a pointer to the library to be changed

   NOTE
    An alert will occur if the checksum fails.

   SEE ALSO
    SetFunction


exec.library/SuperState                  exec.library/SuperState

   NAME
    SuperState -- enter supervisor state with user stack

   SYNOPSIS
    oldSysStack = SuperState()
    D0
    APTR SuperState(void);

   FUNCTION
    Enter supervisor mode while running on the user's stack. The user
    still has access to user stack variables.  Be careful though, the
    user stack must be large enough to accommodate space for all
    interrupt data -- this includes all possible nesting of interrupts.
    This function does nothing when called from supervisor state.

   RESULTS
    oldSysStack - system stack pointer; save this.    It will come in
              handy when you return to user state.  If the system
              is already in supervisor mode, oldSysStack is zero.

   SEE ALSO
    UserState


exec.library/TypeOfMem                     exec.library/TypeOfMem

   NAME
    TypeOfMem -- determine attributes of a given memory address

   SYNOPSIS
    attributes = TypeOfMem(address)
    D0               A1
    ULONG TypeOfMem(void *);

   FUNCTION
    Given a RAM memory address, search the system memory lists and
    return its memory attributes.  The memory attributes are similar to
    those specified when the memory was first allocated: (eg. MEMF_CHIP
    and MEMF_FAST).

    This function is usually used to determine if a particular block of
    memory is within CHIP space.

    If the address is not in known-space, a zero will be returned.
    (Anything that is not RAM, like the ROM or expansion area, will
    return zero.  Also the first few bytes of a memory area are used up
    by the MemHeader.)

   INPUT
    address - a memory address

   RESULT
    attributes - a long word of memory attribute flags.
    If the address is not in known RAM, zero is returned.

   SEE ALSO
    AllocMem()


exec.library/UserState                      exec.library/UserState

   NAME
    UserState -- return to user state with user stack

   SYNOPSIS
    UserState(sysStack)
          D0
    void UserState(APTR);

   FUNCTION
    Return to user state with user stack, from supervisor state with
    user stack.  This function is normally used in conjunction with the
    SuperState function above.

    This function must not be called from the user state.

   INPUT
    sysStack - supervisor stack pointer

   BUGS
    This function is broken in V33 and V34 Kickstart.

   SEE ALSO
    SuperState

exec.library/Vacate                     exec.library/Vacate

   NAME
    Vacate -- release a message lock (semaphore)

   SYNOPSIS
    Vacate(semaphore)
           A0
    void Vacate(struct Semaphore *);

   FUNCTION
    This function releases a previously locked semaphore (see
    the Procure() function).
    If another task is waiting for the semaphore, its bidMessage
    will be sent to its reply port.

   INPUT
    semaphore - the semaport message port representing the
    semaphore to be freed.

   BUGS
    Procure() and Vacate() do not have proven reliability.

   SEE ALSO
    Procure


exec.library/Wait                       exec.library/Wait

   NAME
    Wait -- wait for one or more signals

   SYNOPSIS
    signals = Wait(signalSet)
    D0           D0
    ULONG Wait(ULONG);

   FUNCTION
    This function will cause the current task to suspend waiting for
    one or more signals.  When one or more of the specified signals
    occurs, the task will return to the ready state, and those signals
    will be cleared.

    If a signal occurred prior to calling Wait, the wait condition will
    be immediately satisfied, and the task will continue to run without
    delay.

   CAUTION
    This function cannot be called while in supervisor mode or
    interrupts!  This function will break the action of a Forbid() or
    Disable() call.

   INPUT
    signalSet - The set of signals for which to wait.
            Each bit represents a particular signal.

   RESULTS
    signals - the set of signals that were active

exec.library/WaitIO                     exec.library/WaitIO

   NAME
    WaitIO -- wait for completion of an I/O request

   SYNOPSIS
    error = WaitIO(iORequest)
    D0           A1
    BYTE WaitIO(struct IORequest *);

   FUNCTION
    This function waits for the specified I/O request to complete, then
    removes it from the replyport.    If the I/O has already completed,
    this function will return immediately.

    This function should be used with care, as it does not return until
    the I/O request completes; if the I/O never completes, this
    function will never return, and your task will hang.  If this
    situation is a possibility, it is safer to use the Wait() function.
    Wait() will return return when any of a specified set of signal is
    received.  This is how I/O timeouts can be properly handled.

   WARNING
    If this IORequest was "Quick" or otherwise finished BEFORE this
    call, this function drops though immediately, with no call to
    Wait().  A side effect is that the signal bit related the port may
    remain set.  Expect this.

   INPUTS
    iORequest - pointer to an I/O request block

   RESULTS
    error - zero if successful, else an error is returned
        (a sign extended copy of io_Error).

   SEE ALSO
    DoIO, SendIO, CheckIO, AbortIO

exec.library/WaitPort                       exec.library/WaitPort

   NAME
    WaitPort -- wait for a given port to be non-empty

   SYNOPSIS
    message = WaitPort(port)
    D0           A0
    struct Message *WaitPort(struct MsgPort *);

   FUNCTION
    This function waits for the given port to become non-empty.  If
    necessary, the Wait function will be called to wait for the port
    signal.  If a message is already present at the port, this function
    will return immediately.  The return value is always a pointer to
    the first message queued (but it is not removed from the queue).

   CAUTION
    More than one message may be at the port when this returns.  It is
    proper to call the GetMsg() function in a loop until all messages
    have been handled, then wait for more to arrive.

    To wait for more than one port, combine the signal bits from each
    port into one call to the Wait() function, then use a GetMsg() loop
    to collect any and all messages.  It is possible to get a signal
    for a port WITHOUT a message showing up.  Plan for this.

   INPUT
    port - a pointer to the message port

   RETURN
    message - a pointer to the first available message

   SEE ALSO
    GetMsg