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Assembly Source File | 1989-04-18 | 31.7 KB | 1,257 lines

page ,132 comment ! * netbios version of c-tree server * terminate/stay resident asm lang support * * This program is the CONFIDENTIAL and PROPRIETARY property * of FairCom(R) Corporation. Any unauthorized use, reproduction or * transfer of this program is strictly prohibited. * * Copyright (c) 1987, 1988, 1989 FairCom Corporation * (Subject to limited distribution and * restricted disclosure only.) * *** ALL RIGHTS RESERVED *** * * 4006 West Broadway * Columbia, MO 65203 * * * c-tree(R) Version 4.3 * Release C * February 7, 1989 17:30 * ! ;This module provides the ability to interrupt the main process ;(called user) and resume the ctree server (called task) whenever ;a netbios asynchonous command completes. ; extrn _disconnect:far ;(in ctsmsg.c) undo from netbios include asm.inc DSEG extrn __aintdiv:dword ;dos's div exception vector ptr that ;was saved by c-runtime init code MAXSEG = 20 ;size of _abrktb extrn __abrktb:word ;crt (c runtime) table of blocks ;alloc'd from dos extrn __asegds:word ;crt heaprec for malloc in DGROUP extrn __asizds:word ;crt size of DGROUP extrn __psp:word ;crt addr of program seg prefix ifdef FPLIB extrn __fpinit:word ;at +2 is non 0 if fp library loaded endif CSEG assume ds:nothing ;-------------------------------------------------------------------- ;configuration control ;-------------------------------------------------------------------- ;note: the same source module can be used for any C memory module ;(with appropiate 'far' modifiers). however it is recommended to ;assemble with a define (/D on the masm line) of one of the ;following: SMALL or COMPACT or MEDIUM or LARGE ;example: masm ctstsr /ml /DCOMPACT; ;-------------------------------------------------------------------- DNCB_RETRY = 5*18 ;if an async netbios command cannot ;be started on first try, it is retried ;this many times. the retries occur on ;timer ticks (5*18 == try for 5 seconds) ;comment out next to use dos default of 20 file max FID_TABLE_SZ = 255 ;up to 255 files open ;if FPLIB is defined, then the C floating point emulator vectors ;will be saved/restored for tasks. Define this if necessary to ;use floating point in C code (note. float keys can be used without ;using library. see FPLIB and NO_FPLIB in C code). ;;FPLIB = 1 ;-------------------------------------------------------------------- ; program segment prefix ;-------------------------------------------------------------------- ;-------------------------------------------------------------------- PSP struc pp_int20 dw ? ;+00 exit instruction pp_mtop dw ? ; 02 paragraph past end of mem pp_4 db ? ; 04 pp_cpmcall db ? ; 05 long call opcode pp_cpmmtop dw ? ; 06 long call oprand adj to look like mtop pp_cpmcallseg dw ? ; 08 rest of long call pp_i22term dd ? ; 0a exit to parent addr pp_i23ctlcp dd ? ; 0e ctl-c trap of parent pp_i24cerrp dd ? ; 12 critical err trap of parent pp_parent dw ? ; 16 psp of parent pp_fidtbl db 20 dup (?) ; 18 file id table pp_envseg dw ? ; 2c seg of environment pp_spsave dw ? ; 2e sp save while in dos or execing child pp_sssave dw ? ; 30 ss save " pp_fidtbllen dw ? ; 32 length of fidtbl pp_fidtblptr dd ? ; 34 ptr to fidtbl pp_shr0 dw ? ; 38 set to ffff (used by share.exe) pp_shr1 dw ? ; 3a set to ffff (used by share.exe) db 14h dup (?) ; 3c pp_call50 dw ? ; 50 old convention dos entry pp_call50ret db ? ; 52 db 09h dup (?) ; 53 pp_fcb0 db 16 dup (?) ; 5c pp_fcb1 db 16 dup (?) ; 6c db 4 dup (?) ; 7c pp_cmdtail db 128 dup (?) ; 80 PSP ends ;-------------------------------------------------------------------- ;DOSSTATE structure ;-------------------------------------------------------------------- ; msdos 3.x user context area - everything except current directorys ; the address of this table is obtained with DOS 5d06h call: ; in: ax = 5d06h ; out: ds:si = addr of context data ; dx = len of context data when in_dos flag clear ; cx = len of context data when in_dos flag set ; (struc of this small context is shown below) ;-------------------------------------------------------------------- DOSSTATE struc dst_in_i24 db ? ;00 dos is in int 24 counting flag dst_in_dos db ? ;01 dos is in use counting flag dst_wpe_drv db ? ;02 drive number of write prot error dst_errloc db ? ;03 extended error locus dst_err dw ? ;04 extended error dst_erract db ? ;06 extended error suggested action dst_errclass db ? ;07 extended error class dst_errvol dd ? ;08 extended error volume label ptr dst_dta dd ? ;0c data transfer address dst_psp dw ? ;10 program segment prefix dst_i23_sp dw ? ;12 sp save during int 23 dst_retcode dw ? ;14 dos return code dst_defdrv db ? ;16 default drive dst_breakon db ? ;17 check for ctl-break on/off flag ;18h sizeof dosstate DOSSTATE ends ;-------------------------------------------------------------------- ;CONTEXT structure ;-------------------------------------------------------------------- ;this is the layout of context data saved for both the user and the ;task programs. ;-------------------------------------------------------------------- ifdef FPLIB CONTEXT struc co_ifp dd 11 dup (?) ;floating pt int vects 34-3e co_i1b dd ? ;int 1b vector (kbd break) co_i23 dd ? ;int 23 vector (dos ^C) co_i24 dd ? ;int 24 vector (dos critical error) co_dssz dw ? ;size used in next member co_dosstate db ? ;buffer for psp, dta etc ; (actually more than one byte long ; so make sure its last in struc) CONTEXT ends else ;(NO_FPLIB) CONTEXT struc co_i1b dd ? ;int 1b vector (kbd break) co_i23 dd ? ;int 23 vector (dos ^C) co_i24 dd ? ;int 24 vector (dos critical error) co_dssz dw ? ;size used in next member co_dosstate db ? ;buffer for psp, dta etc ; (actually more than one byte long ; so make sure its last in struc) CONTEXT ends endif ;-------------------------------------------------------------------- ; netbios command block ;-------------------------------------------------------------------- ;the ncb_next field is used in here to link together netbios commands ;that cannot be started right away (in case netbios runs out of ;resources) ;-------------------------------------------------------------------- NCBanr = 80h ; network command block NCB struc ncb_cmd db ? ;command code ncb_err db ? ;error return ncb_lsn db ? ;session id ncb_namenum db ? ;name number ncb_bufptr dd ? ;buffer address ncb_buflen dw ? ;buffer length ncb_rname db 16 dup (?) ;remote name ncb_lname db 16 dup (?) ;local name ncb_rto db ? ;receive timeout ncb_sto db ? ;send timeout ncb_anrptr dd ? ;anr entry ncb_lana db ? ;adapter number ncb_done db ? ;cmd complete when not ff ncb_next dd ? ;* next on list ncb_res1 dd ? ;* ncb_res2 db 6 dup (?) ;* NCB ends ;* used only by netbios ;-------------------------------------------------------------------- ;local data ;-------------------------------------------------------------------- ;all this data is in the code segment for easy addressibilty from ;int trap routines ;-------------------------------------------------------------------- ifdef DEBUG public i08_passon,i13_passon,i21_passon,i28_passon,i2a_passon public u_sp,u_ss,u_ctxt_ptr,t_sp,t_ss,t_ctxt_ptr public dos_state,dctx_szsmall,dctx_szlarge ifdef FPLIB public usefp_flag endif public task_pending,in_task_flag public dncb_head,dncb_retry endif ; --- original vectors for interrupts trapped --- even i08_passon dd ? ;timer tick i13_passon dd ? ;disk i/o i21_passon dd ? ;dos entry i28_passon dd ? ;dos idle while waiting for console i2a_passon dd ? ;dos idle while waiting for device (ah=84h) ; --- save areas for context switches --- even u_sp dw OTX init_ustk ;user sp save when in task context u_ss dw seg _TEXT u_ctxt_ptr dd ? ;save area for user context t_sp dw ? ;task sp save when in user context t_ss dw ? t_ctxt_ptr dd ? ;save area for task context dos_state dd ? ;pointer to dos variables dctx_szsmall dw ? ;size of dos variables for context sw. ; when dos not busy or int 28 task switch ; typically 24 bytes dctx_szlarge dw ? ;size of dos variables for context sw. ; when int 2a, ah=84 task switch ; typically some 2k bytes ifdef FPLIB usefp_flag dw 0 ;set to one if fp library loaded endif ; --- task switch control --- even task_pending dw 0 ;task event happened in_task_flag dw 0 ;task is active task_inhib_flags dw 0 ;bits set to inhibit task activate had_i2a84 dw 0 ;counts how many times int 24, ah=84h ;occurred since last netbios event. DOS ;issues this when it is polling a char ;device and dos can be safely interrupted, ;however, large DOS data area has to be ;saved. therefore this counter inhibits ;switching in case an int 28 (smaller save) ;comes along timeout dw 0 ;clock tick downcounter schedules task on 0 had_timeout dw 0 ;had timeout flag ; --- delayed start ncbs --- even dncb_head dd 0 ;ncb's to be started when netbios allows it dncb_retry dw 0 ;retry counter for delayed start ncbs ; --- fixed up user's stack for first call to wait_task --- ;this will go to code that does and int 21 with ax = term, stay resident ifdef DEBUG public init_ustk, task_memsize endif even dw 64 dup (?) ;slack init_ustk dw 0 ;bx dw 0 ;cx task_memsize dw ? ;dx dw 0 ;si dw 0 ;di dw 0 ;bp dw seg _TEXT ;ds dw seg _TEXT ;es dw OTX go_tsr ;near ret ; ;replacement file-id so dos can open more than 20 files ; ifdef FID_TABLE_SZ ifdef DEBUG public fid_table endif fid_table db FID_TABLE_SZ dup (0ffh) endif ;-------------------------------------------------------------------- ;UCOUNT do_nb(NCB far *) ;-------------------------------------------------------------------- ;this is called from ctnbios to issue command to netbios. if the ;command cannot be started, then it will be reissued periodically ;from timer tick trap. ;-------------------------------------------------------------------- public _do_nb _do_nb proc far push bp mov bp,sp les bx,[bp+6] ;es:bx -> ncb int 5ch ;call netbios or al,al jz ast4 ;if no immed err test es:[bx].ncb_cmd,NCBanr jz ast4 ;if not a nowait cmd cmp es:[bx].ncb_cmd,0ffh jz ast4 ;if just an install check mov es:[bx].ncb_done,0ffh ;simulate cmd in progress mov es:[bx].ncb_err,0ffh mov WO es:[bx].ncb_next,0 ;put on can't start list mov WO es:[bx].ncb_next + 2,0 PUSHM <ds,si> cli lds si,cs:dncb_head mov ax,ds or ax,si jnz ast1 mov WO cs:dncb_head,bx ;list is empty so put at top mov WO cs:dncb_head + 2,es mov dncb_retry,DNCB_RETRY jmp ast3 ;return success ast1: mov ax,WO [si].ncb_next or ax,WO [si].ncb_next+2 jz ast2 ;found end lds si,[si].ncb_next ;keep looking jmp ast1 ast2: mov WO [si].ncb_next,bx ;put on end mov WO [si].ncb_next + 2,es ast3: sti POPM <si,ds> xor ax,ax ;return success ast4: mov ah,0 ;success (if nowait) or err code pop bp ret _do_nb endp ;-------------------------------------------------------------------- ;chk_ancb_start ;-------------------------------------------------------------------- ;called from timer tick trap to see if any ncb's are on can't start ;list. if any are on the list, a start is attempted. eventually ;a timeout will occur and then the command complete will be simulated ;with error sts. ;-------------------------------------------------------------------- ifdef DEBUG public chk_ancb_start endif chk_ancb_start: PUSHM <ax,bx,es> cas1: les bx,cs:dncb_head mov ax,es or ax,bx jz cas4 ;if list empty mov ax,WO es:[bx].ncb_next ;remove 1st mov WO cs:dncb_head,ax mov ax,WO es:[bx].ncb_next + 2 mov WO cs:dncb_head + 2,ax int 5ch ;try to start or al,al jnz cas2 ;if no luck mov cs:dncb_retry,DNCB_RETRY ;good, restart timeout jmp cas1 ;try to start another cas2: dec cs:dncb_retry ;check timeout jnz cas3 ;if not timeout pushf cli call es:[bx].ncb_anrptr ;command complete mov cs:dncb_retry,1 ;fail the rest jmp cas1 cas3: mov es:[bx].ncb_done,0ffh ;no timeout, requeue mov es:[bx].ncb_err,0ffh mov ax,WO cs:dncb_head mov WO es:[bx].ncb_next,ax mov ax,WO cs:dncb_head + 2 mov WO es:[bx].ncb_next + 2,ax cas4: POPM <es,bx,ax> ret ;-------------------------------------------------------------------- ;misc dos traps ;-------------------------------------------------------------------- ;these are set during task (server) context ;i24 (critical err) just causes dos call to fail ;i23 (ctl-brk dos) don't let user trap get control ;i1b (ctl-brk bios) " " " " " " ; ;note: during heavy server activity ctl-brks may get lost. ;-------------------------------------------------------------------- ;misc default traps for task context ifdef DEBUG public i24_trap,i1b_trap,i23_trap endif i24_trap: mov al,3 ;fail the call i1b_trap: i23_trap: iret ;-------------------------------------------------------------------- ;int 8 trap ;-------------------------------------------------------------------- ;check timeout specified on call to task_wait. schedule task if ;timer runs out ;-------------------------------------------------------------------- ifdef DEBUG public i08_trap endif i08_trap: pushf call cs:i08_passon call chk_ancb_start ;service netbios cmds needing start cmp cs:in_task_flag,0 jnz tk2 ;if already in task cmp cs:timeout,0 jz tk1 ;if no timeout or already timed out dec cs:timeout jnz tk1 ;if didn't time out mov cs:had_timeout,-1 ;set flag mov cs:task_pending,1 ;schedule server tk1: call chk_dotask ;run task if needed and possible tk2: iret ;-------------------------------------------------------------------- ;int 13 trap ;-------------------------------------------------------------------- ;inhibit task switch if user program calls bios direct ;-------------------------------------------------------------------- ifdef DEBUG public i13_trap endif i13_trap: or cs:task_inhib_flags,1 pushf call cs:i13_passon pushf and cs:task_inhib_flags,not 1 call chk_dotask popf sti retf 2 ;-------------------------------------------------------------------- ;int 21 trap ;-------------------------------------------------------------------- ;during user context: ; trapped to give more opportunities to run task when event pending ;during task context: ; trapped to (1) force error on mem alloc's (2) clean up if task ; terminates ;-------------------------------------------------------------------- ifdef DEBUG public i21_trap endif i21_trap: cmp cs:in_task_flag,0 jnz dtr2 ;if server task context ;selected calls will be passed onto dos without our ret ;info on the stack. In those cases we're just outta luck ;until the next dos call cmp ah,0 ;terminate jz dtr1 cmp ah,26h ;build psp jz dtr1 cmp ah,4bh ;exec jz dtr1 ;manipulate to get user's orig flags push ax push bp mov bp,sp mov ax,[bp+8] xchg ax,[bp+2] pop bp call cs:i21_passon ;perform the dos func push bp mov bp,sp pushf pop WO [bp+6] ;in case dos returned info in flags pop bp call chk_dotask iret dtr1: jmp cs:i21_passon dtr2: cmp ah,4ch ;terminate? jz killtask cmp ah,48h ;alloc? jz dtr3 cmp ah,4ah ;mod alloc? jnz dtr1 dtr3: mov ax,8 ;no mem dos err xor bx,bx stc sti retf 2 ;-------------------------------------------------------------------- ;killtask ;-------------------------------------------------------------------- ;entered from i21_trap if server task issued dos terminate call ;unhook from ints, undo netbios connections, release all memory ;and vanish into thin air ; ;NOTE: if this is to be used with other tsr's, then they should ;be removed first if they are loaded after this. It might also be ;possible to look at int vectors and deduce another tsr is loaded ;and, if so, not completely eliminate ourselves. ;-------------------------------------------------------------------- ifdef DEBUG public killtask, clsall endif killtask: mov ax,DGROUP mov ds,ax assume ds:DGROUP ;kill netbios connections if not already done call _disconnect ;in ctsmsg.c push ds assume ds:nothing ;unlink int traps lds dx,cs:i08_passon DOS 2508h lds dx,cs:i13_passon DOS 2513h lds dx,cs:i21_passon DOS 2521h lds dx,cs:i28_passon DOS 2528h lds dx,cs:i2a_passon DOS 252ah pop ds assume ds:DGROUP ;close all open files mov es,__psp push ds lds si,es:[0].pp_fidtblptr mov cx,es:[0].pp_fidtbllen xor bx,bx clsall: cmp BY [si+bx],0ffh jz cla1 DOS 3eh cla1: inc bx loop clsall pop ds ;free all memory associated with task mov es,__psp mov ax,es:[0].pp_envseg ;env ptr mov es,ax or ax,ax jz kt1 DOS 49h ;free env kt1: lea si,__abrktb+4 ;free all far segs mov cx,MAXSEG-1 kt2: mov ax,[si+2] or ax,ax jz kt3 mov es,ax DOS 49h add si,4 loop kt2 kt3: mov es,__psp ;free the main seg DOS 49h ;return to interrupted thread mov cs:task_pending,0 call far ptr _task_wait ;won't return assume ds:nothing ;-------------------------------------------------------------------- ;int 28 ;-------------------------------------------------------------------- ;dos issues this when it is polling keyboard ;-------------------------------------------------------------------- ifdef DEBUG public i28_trap endif i28_trap: cmp cs:task_pending,0 jz i281 cmp cs:in_task_flag,0 jnz i281 push ax call do_task_sm pop ax i281: jmp cs:i28_passon ;-------------------------------------------------------------------- ;int 2a ;-------------------------------------------------------------------- ;dos issues this when it is polling char device. if a task switch ;is desired from this point, a large amount of data inside dos has ;to be saved. therefore a counter is used to slow down usage in the ;hope that a int 28 will occur ;-------------------------------------------------------------------- ifdef DEBUG public i2a_trap endif i2a_trap: cmp ah,84h jz i2a2 i2a1: jmp cs:i2a_passon i2a2: cmp cs:task_pending,0 jz i2a1 cmp cs:in_task_flag,0 jnz i2a1 inc cs:had_i2a84 cmp cs:had_i2a84,3 jb i2a1 push ax mov ax,cs:dctx_szlarge call do_task pop ax iret ;-------------------------------------------------------------------- ;fanrf - async netbios command completed notification ;-------------------------------------------------------------------- ;all async ncbs from server have an extra word in front that is set ;to 1 by this when command completes. task_pending flag is set in ;case system state is such that the server can't be resumed ; ;note: ; some netbios' may call this routine with the hardware int service ; routine still pending. In this case we dont want to run the server ; because this in-service interrupt will likely block the disk controller ; interrupt. (a less-common but possible case is nested ints where another ; is higher than disk-ctrlr). ; ; if the netbios does this, then the system will still work but ; performance will be degraded. ; ; One solution is to identify the netbios hdwe interrupt and trap ; it in here. For example for IRQ3. add set trap in task_init and ; clear trap in killtask. ; ; i0b_trap: ; pushf ; call cs:i0b_passon ; call chk_dotask ;switch tasks when isr bit clear ; iret ;-------------------------------------------------------------------- ;es:bx -> ncb that has a word flag in front of it public _fanrf _fanrf proc far mov WO es:[bx-2],1 ;set done flag (xncb.f) mov cs:had_timeout,0 inc cs:task_pending mov cs:had_i2a84,0 cmp cs:in_task_flag,0 jnz fanr1 ;***************** push ax mov al,0bh ;read in-service reg out 20h,al in al,20h and al,0ffh pop ax ;***************** jnz fanr1 ;inhibit task switch in hardware isr call chk_dotask fanr1: iret _fanrf endp ;-------------------------------------------------------------------- ;clear_task_events() ;-------------------------------------------------------------------- ;server calls this just prior to polling all possible events. this ;avoids a redundant poll pass. ;-------------------------------------------------------------------- public _clear_task_events _clear_task_events proc far mov cs:task_pending,0 ret _clear_task_events endp ;-------------------------------------------------------------------- ;chk_dotask ;-------------------------------------------------------------------- ;called from various int traps and event processors to see if it is ;desired and possible to switch to server task ;-------------------------------------------------------------------- ifdef DEBUG public chk_dotask endif chk_dotask: cmp cs:task_pending,0 jz cdt1 ;if no event pending cmp cs:in_task_flag,0 jnz cdt1 ;if already in task cmp cs:task_inhib_flags,0 jnz cdt1 ;if misc lockout flags set PUSHM <ds,si> lds si,cs:dos_state cmp WO [si],0 POPM <si,ds> jnz cdt1 ;if user in dos, then wait till ;(1) user exits (2) int 28 (3) int 2a push ax call do_task_sm ;switch, saving small part of dos vars pop ax cdt1: ret ;-------------------------------------------------------------------- ;UCOUNT task_wait(timeout) ;-------------------------------------------------------------------- ;called from server (ctsmsg) to wait for event. The user process is ;resumed. The first time this is called, the user process has been ;set up to be a tsr call to dos, which gets back to command.com ;returns -1 if event was timeout, else 0 ;-------------------------------------------------------------------- public _task_wait _task_wait proc far push bp mov bp,sp mov ax,[bp+6] ;get timeout value pop bp mov cs:timeout,ax cmp cs:task_pending,0 ;chk if new event already queued jz tw1 xor ax,ax mov cs:task_pending,ax ret ;ret right away if so tw1: ;save server task context PUSHM <es,ds,bp,di,si,dx,cx,bx> mov t_sp,sp ;save task's sp mov t_ss,ss les di,cs:t_ctxt_ptr;save task's context mov ax,cs:dctx_szsmall call save_context ;restore user context lds si,cs:u_ctxt_ptr;get user's context call restore_context cli mov ss,u_ss ;user's sp restored mov sp,u_sp sti POPM <bx,cx,dx,si,di,bp,ds,es> ;one last check for new event occurred cli cmp cs:task_pending,0 jnz do_task ;got one, so switch back with ax set mov cs:in_task_flag,0 sti _task_wait endp ret ;resume trap, which will ret ;to int'd user ;-------------------------------------------------------------------- ;do_task and do_task_sm ;-------------------------------------------------------------------- ;called when (1) in user context (2) server event pending and (3) dos ;not in use or at task-switch checkpoint ; ;this suspends the user and resumes the server task (ie, return from ;task_wait()) ;-------------------------------------------------------------------- ifdef DEBUG public do_task, do_task_sm endif do_task_sm: mov ax,cs:dctx_szsmall do_task: ;ax has dos save size mov cs:in_task_flag,1 ;set in task context sti PUSHM <es,ds,bp,di,si,dx,cx,bx> ;save user's regs mov cs:u_sp,sp ;save user's sp mov cs:u_ss,ss cli mov ss,cs:t_ss ;restore task's stack mov sp,cs:t_sp sti les di,cs:u_ctxt_ptr ;save user's context call save_context lds si,cs:t_ctxt_ptr ;restore task's context call restore_context POPM <bx,cx,dx,si,di,bp,ds,es> ;restore task's regs xor ax,ax mov cs:task_pending,ax ;clear task pending flag xchg ax,cs:had_timeout ;get had timeout for return retf ;-------------------------------------------------------------------- ;save_context ;-------------------------------------------------------------------- ;utility used to save current context ;in: ; es:di = save area ; ax is size of dos context to save ;out: ; ax,di,si,ds destroyed ; ;-------------------------------------------------------------------- ifdef DEBUG public save_context endif save_context: cld xor cx,cx mov ds,cx ifdef FPLIB cmp cs:usefp_flag,0 ;save fp ints if used jnz gc2 add di,11*4 ;else skip fp save area jmp short gc3 gc2: mov si,34h*4 mov cx,11*2 rep movsw gc3: endif mov si,1bh*4 ;get int 1b vect movsw movsw mov si,23h*4 ;get ints 23,24 vects movsw movsw movsw movsw stosw ;dos context save size mov cx,ax lds si,cs:dos_state ;get dos user context shr cx,1 rep movsw jnc gc1 movsb gc1: ret ;-------------------------------------------------------------------- ;restore_context ;-------------------------------------------------------------------- ;utility used to save current context ;in: ; ds:si = save area ;out: ; ax size of restored dos context ; cx,di,si,es destroyed ; ;-------------------------------------------------------------------- ifdef DEBUG public restore_context endif restore_context: cld xor ax,ax mov es,ax ifdef FPLIB cmp cs:usefp_flag,0 ;restore fp ints if used jnz sc2 add si,11*4 ;else skip fp save area jmp short sc3 sc2: mov di,34h*4 mov cx,11*2 rep movsw sc3: endif mov di,1bh*4 ;set int 1b vect cli movsw movsw mov di,23h*4 ;get ints 23,24 vects movsw movsw movsw movsw sti lodsw ;dos context save size mov cx,ax les di,cs:dos_state ;set dos user context push [si].dst_psp ;get psp for restore shr cx,1 rep movsw jnc sc1 movsb sc1: pop cx push ax push bx mov ah,50h mov bx,cx pushf cli call cs:i21_passon pop bx pop ax ret ;-------------------------------------------------------------------- ;task_init(ctxtsavebufptr) ;-------------------------------------------------------------------- ;called from ctsmsg to divide the system into two processes -- the ;user and the server task. When it returns, the server task is ;running and the user is suspended. When the server suspends, the ;user will resume at a go term/stay resident instruction, which will ;return to the shell, leaving the server in memory (the user has its ;own little stack for this exit process) ; ;for the C small and medium models, this cuts off the heap at its ;first free space. for other models, the thing to do is link ;with /CP:1 as noted in MS C users guide ; ;the dos internal handle table is moved to a bigger area so more ;files can be opened by the server task. ;-------------------------------------------------------------------- __savebuf = 6 ifdef DEBUG public go_tsr endif ;the code for the initial 'user task' go_tsr: mov ax,3100h int 21h public _task_init _task_init proc far assume ds:DGROUP push bp mov bp,sp push di push si call fxalloc ;cut off mainseg if possible, get size of it ifdef FPLIB ;set flag if fp lib used mov ax,__fpinit+2 mov cs:usefp_flag,ax ;non 0 if in use endif push ds ifdef FID_TABLE_SZ ; set bigger file id table for dos mov es,__psp lds si,es:[0].pp_fidtblptr assume ds:nothing mov cx,es:[0].pp_fidtbllen cmp cx,FID_TABLE_SZ jae iti2 mov di,OTX fid_table mov WO es:[0].pp_fidtblptr,di mov WO es:[0].pp_fidtblptr+2,cs mov es:[0].pp_fidtbllen,FID_TABLE_SZ push cs pop es rep movsb ;copy already open file ids iti2: endif assume ds:nothing push cs pop ds assume ds:_TEXT ; set ptrs to context save areas mov ax,[bp+__savebuf+2] ;segment mov WO u_ctxt_ptr+2,ax mov WO t_ctxt_ptr+2,ax mov ax,[bp+__savebuf] ;offset mov WO u_ctxt_ptr,ax mov bx,dctx_szlarge add bx,size CONTEXT - 1 inc bx and bx,not 1 add ax,bx mov WO t_ctxt_ptr,ax ; copy current context to user context save les di,u_ctxt_ptr ;save user's context mov ax,dctx_szsmall push ds call save_context pop ds ; if fp lib in use, try to find a vector to an iret in dos so ; int vectors will look cleaner (cosmetic) ifdef FPLIB cmp cs:usefp_flag,0 jz civ2 xor ax,ax mov ds,ax lds bx,ds:[3fh*4] mov ax,ds cmp ax,WO cs:dos_state+2 jnz civ2 mov al,[bx] ;get ins at ds:bx cmp al,0cfh ;iretins jnz civ2 les di,cs:u_ctxt_ptr add di,co_ifp ;fix up fp ints in saved user state mov cx,11 civ1: mov ax,bx stosw mov ax,ds stosw loop civ1 civ2: endif push cs pop ds ; turn off break checking mov dl,0 DOS 3301h ; save int vectors it3: DOS 3508h mov WO i08_passon,bx mov WO i08_passon+2,es DOS 3513h mov WO i13_passon,bx mov WO i13_passon+2,es DOS 3521h mov WO i21_passon,bx mov WO i21_passon+2,es DOS 3528h mov WO i28_passon,bx mov WO i28_passon+2,es DOS 352ah mov WO i2a_passon,bx mov WO i2a_passon+2,es mov cs:in_task_flag,1 ;set in task ;set int vect traps mov dx,OTX i08_trap DOS 2508h mov dx,OTX i13_trap DOS 2513h mov dx,OTX i21_trap DOS 2521h mov dx,OTX i28_trap DOS 2528h mov dx,OTX i2a_trap DOS 252ah ;set up error traps mov dx,OTX i1b_trap DOS 251bh mov dx,OTX i23_trap DOS 2523h mov dx,OTX i24_trap DOS 2524h ; restore dos's div by 0 trap mov ax,seg DGROUP mov ds,ax assume ds:DGROUP lds dx,__aintdiv assume ds:nothing DOS 2500h xor ax,ax itxit: pop ds assume ds:nothing pop si pop di pop bp ret _task_init endp ;-------------------------------------------------------------------- ;fxalloc ;-------------------------------------------------------------------- ;if no _fmallocs have been done, this cuts off the main data seg ;just past last used heap space. This works for MSC 3 and 4, and ;probably for 5 too. ; ;the size of the main segment (psp to end of data seg) is saved ;for the TSR parameter ;-------------------------------------------------------------------- ifdef DEBUG public fxalloc endif assume ds:DGROUP fxalloc: cmp __abrktb+6,0 ;_abrktb[1].sg jnz fx6 mov si,__asegds+0 ;_asegds.bottom or si,si jnz fx1 mov di,__abrktb ;__abrktb[0].sz jmp fx5a ;make di end of dseg fx1: mov __asegds+2,si ;_asegds.roveroff xor di,di fx2: mov ax,[si] cmp ax,0fffeh jz fx4 test ax,1 jnz fx3 mov di,si ;last alloc'd block found fx3: and ax,not 1 add si,ax add si,2 jmp fx2 fx4: or di,di jnz fx5 mov di,__abrktb mov WO [di],1 ;dummy free block fx5: mov ax,[di] and ax,not 1 add di,ax add di,2 mov WO [di],0fffeh add di,2 mov __asegds+6,di ;_asegds.top mov __abrktb,di ;_abrktb[0].sz fx5a: mov __asizds,di mov ax,di add ax,15 rcr ax,1 mov cl,3 shr ax,cl mov es,__psp mov bx,ds add ax,bx mov es:[0].pp_mtop,ax DOS 4ah fx6: mov bx,__psp mov es,bx mov ax,es:[0].pp_mtop ;get main seg size sub ax,bx mov cs:task_memsize,ax ret assume ds:nothing ;-------------------------------------------------------------------- ;UCOUNT task_preinit() ;-------------------------------------------------------------------- ;this returns the size of a buffer needed at task_init() time. ;0 is returned if not dos 3 ;-------------------------------------------------------------------- ; get adr, len of dos data for context switches ;returns length of area to be alloc'd ; or NULL if bad dos ver public _task_preinit _task_preinit proc far push bp mov bp,sp push di push si ; check dos version DOS 30h cmp al,3 jz tpi1 xor ax,ax ;return NULL for bad dos ver jmp tpi2 tpi1: push ds DOS 5d06h ;see notes in struc section mov ax,ds pop ds mov WO cs:dos_state,si mov WO cs:dos_state+2,ax mov cs:dctx_szsmall,dx mov cs:dctx_szlarge,cx mov ax,cx add ax,size CONTEXT - 1 inc ax and ax,not 1 shl ax,1 tpi2: pop si pop di pop bp ret _task_preinit endp END_MOD end