Chip 1994 February/CHIP0294.ISO/digital/magazin/trumpet/pktdrvs/trace.asm

Assembly Source File | 1993-09-29 | 15.0 KB | 715 lines

version    equ    1
;History:697,1

    include    defs.asm

;  Copyright, 1988-1992, Russell Nelson, Crynwr Software

;   This program is free software; you can redistribute it and/or modify
;   it under the terms of the GNU General Public License as published by
;   the Free Software Foundation, version 1.
;
;   This program is distributed in the hope that it will be useful,
;   but WITHOUT ANY WARRANTY; without even the implied warranty of
;   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;   GNU General Public License for more details.
;
;   You should have received a copy of the GNU General Public License
;   along with this program; if not, write to the Free Software
;   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

code    segment word public
    assume    cs:code, ds:code

    org    2ch
phd_env    label    word

    org    5ch
phd_fcb1    label    byte

    org    6ch
phd_fcb2    label    byte

    org    80h
phd_dioa    label    byte

    org    100h
start:
    jmp    start_1

stack    label    byte

comment /

Plan:

Keep a circular queue of events.  The size of the queue is a settable
parameter.  Discard events that fall off the end.  Remember how many events
were discarded.  Remember when the events occurred.

Type of events to remember:
    calls to the packet driver
    upcalls to the receiver handler (both kinds)

/

; In addition to the function numbers specified in the FTP Software
; packet driver spec, the following pseudo-functions are defined:

EVENT_RECEIVE    equ    255        ;receiver upcall.

event_struc    struc
event_length    dw    ?        ;length of this event.
event_function    db    ?        ;the event function number.
event_time    dw    ?,?        ;timer tick at the time of the call.
event_error    db    ?        ;set to value of dh after the SWI.
event_struc    ends

di_struc    struc
        db    (size event_struc) dup (?)
di_version    dw    ?
di_class    db    ?
di_type        dw    ?
di_number    db    ?
di_basic    db    ?
di_struc    ends

at_struc    struc
        db    (size event_struc) dup (?)
at_if_class    db    ?
at_if_type    dw    ?
at_if_number    db    ?
at_typelen    dw    ?
at_handle    dw    ?
at_struc    ends

handle_struc    struc
        db    (size event_struc) dup (?)
event_handle    dw    ?
handle_struc    ends

ga_struc    struc
        db    (size event_struc) dup (?)
ga_handle    dw    ?
ga_length    dw    ?
ga_struc    ends

srm_struc    struc
        db    (size event_struc) dup (?)
srm_mode    dw    ?
srm_handle    dw    ?
srm_struc    ends

queue_length    dw    10000,?        ;length of the queue.
queue_tail    dw    ?        ;points after the last item in the queue.
queue_ptr    dw    ?        ;points to the new item in the queue.
queue_head    dw    ?        ;points to the first item in the queue.
queue_end    dw    ?        ;points to the end of the queue, but
                    ;there is room for one more event after
                    ;this one.

entry_point    db    ?,0,0,0

parm    dw    0
parm2    dw    their_dioa,?
parm3    dw    phd_fcb1,?
parm4    dw    phd_fcb2,?

comspec_env_str    db    "COMSPEC="
comspec_env_len    equ    $-comspec_env_str

program        db    64 dup(?)
their_dioa    db    0,0dh,128-2 dup(?)

saved_ax    label    word
saved_al    db    ?
saved_ah    db    ?
saved_bx    dw    ?
saved_ds    dw    ?
saved_f        dw    ?

functions    label    word
    dw    f_driver_info        ;function 1
    dw    f_access_type
    dw    f_release_type
    dw    f_send_pkt
    dw    f_terminate
    dw    f_get_address
    dw    f_reset_interface    ;function 7
    dw    f_set_rcv_mode        ;function 20
    dw    f_get_rcv_mode
    dw    f_set_multicast_list
    dw    f_get_multicast_list
    dw    f_get_statistics
    dw    f_set_address        ;function 25

their_isr    dd    ?

our_isr:
    jmp    our_isr_0        ;the required signature.
    db    'PKT DRVR',0

our_isr_0:
    assume    ds:nothing
    mov    saved_ds,ds
    mov    saved_bx,bx
    mov    saved_ax,ax
    cld

    mov    bx,sp
    mov    bx,ss:[bx+4]        ;get the original flags.
    mov    saved_f,bx


    mov    bx,cs            ;set up ds.
    mov    ds,bx
    assume    ds:code

;the following code runs with ax, bx, ds, and flags saved in save_*.
;otherwise, all the registers are the same as those we were called with.

    mov    bl,ah            ;jump to the correct function.
    mov    bh,0
    cmp    bx,7            ;highest function is 7.
    jbe    our_isr_3
    cmp    bx,20
    jb    our_isr_bad
    cmp    bx,25
    ja    our_isr_bad
    sub    bx,20-7-1        ;map 20 right after 7.
our_isr_3:
    add    bx,bx            ;*2
    jmp    functions-2[bx]        ;table starts at 1.

our_isr_bad:
    call    do_their_isr
    jmp    our_isr_done

f_driver_info:
    mov    bx,(size di_struc)
    call    queue_advance
    call    do_their_isr
    jc    f_driver_info_1

    mov    ax,saved_bx
    mov    [bx].di_version,ax
    mov    [bx].di_class,ch
    mov    [bx].di_type,dx
    mov    [bx].di_number,cl
    mov    al,saved_al
    mov    [bx].di_basic,al
;we ignore the name -- too much work.
f_driver_info_1:
    jmp    our_isr_done

f_get_statistics:
;strictly speaking, we should remember the statistics, but I'm not going to now.
f_terminate:
f_reset_interface:
f_release_type:
f_get_rcv_mode:
    mov    bx,(size handle_struc)
    call    queue_advance
    mov    ax,saved_bx
    mov    [bx].event_handle,ax
    call    do_their_isr
    jmp    our_isr_done

f_access_type:
    mov    bx,(size at_struc)
    call    queue_advance
    mov    al,saved_al
    mov    [bx].at_if_class,al
    mov    ax,saved_bx
    mov    [bx].at_if_type,ax
    mov    [bx].at_if_number,dl
    mov    [bx].at_typelen,cx
    mov    their_recv.segm,es
    mov    their_recv.offs,di
    mov    ax,cs            ;and stick our receiver in.
    mov    es,ax
    mov    di,offset our_recv
    call    do_their_isr
    jc    f_access_type_1
    mov    ax,saved_ax
    mov    [bx].at_handle,ax
f_access_type_1:
    les    di,their_recv        ;now restore ds and si.
    jmp    our_isr_done


f_send_pkt:
    mov    bx,(size event_struc)
    add    bx,cx
    call    queue_advance
;make a copy of their packet.
    push    cx
    push    si
    push    di
    push    ds
    push    es
    lea    di,[bx] + (size event_struc)
    mov    ax,cs
    mov    es,ax
    mov    ds,saved_ds
    rep    movsb
    pop    es
    pop    ds
    pop    di
    pop    si
    pop    cx
    call    do_their_isr
    jmp    our_isr_done

f_get_address:
    mov    bx,(size ga_struc)
    add    bx,cx
    call    queue_advance
    mov    ax,saved_bx        ;save their handle
    mov    [bx].ga_handle,ax
    call    do_their_isr
    jc    f_get_address_1
;make a copy of their address.
    mov    [bx].ga_length,cx    ;we need to save this because it
                    ;might be less than the total allocated.
    push    cx
    push    si
    push    di
    push    ds
    push    es
    mov    si,di            ;get es:di into ds:si
    mov    ax,es
    mov    ds,ax
    lea    di,[bx] + (size ga_struc)    ;get our pointer into es:di.
    mov    ax,cs
    mov    es,ax
    rep    movsb
    pop    es
    pop    ds
    pop    di
    pop    si
    pop    cx
f_get_address_1:
    jmp    our_isr_done


f_set_rcv_mode:
    mov    bx,(size srm_struc)
    add    bx,2
    call    queue_advance
    mov    ax,saved_bx        ;save their handle.
    mov    [bx].srm_handle,ax
    mov    [bx].srm_mode,cx    ;save their mode.
    call    do_their_isr
    jmp    our_isr_done

f_set_multicast_list:
f_get_multicast_list:
f_set_address:
    mov    bx,(size event_struc)
    call    queue_advance
    call    do_their_isr

our_isr_done:
    push    saved_f            ;restore their flags, see [2]
    popf

    mov    ax,saved_ax
    mov    bx,saved_bx
    mov    ds,saved_ds        ;restore the two registers we destroyed.
    assume    ds:nothing

    retf    2            ;return, popping their old flags, [2].
    assume    ds:code


;do_their_isr executes their isr with the original registers.
;called with all their registers except f, ds, and bx.
;exits with all their registers except ds, ax, and bx.  bx is queue_ptr
do_their_isr:

;setup their context.
    mov    ax,saved_f        ;restore their flags, see [1]
    and    ax,not 200h        ;clear the interrupt flag, as required
    push    ax            ;  when faking an interrupt.
    mov    ax,saved_ax
    mov    bx,saved_bx
    mov    ds,saved_ds        ;restore the two registers we destroyed.
    assume    ds:nothing

;    [1] we pushed the flags earlier.
    call    their_isr        ;now fake their interrupt.

;save their context.
    mov    saved_ax,ax        ;save the new registers.
    mov    saved_bx,bx
    mov    saved_ds,ds
    mov    ax,cs            ;set up a pointer to the next event.
    mov    ds,ax
    assume    ds:code
    pushf                ;save the new flags.
    pop    ax
    and    saved_f,200h        ;merge the interrupt flag in saved_f
    or    saved_f,ax        ;  with the new flags.

;remember whether it succeeded or not.
    mov    bx,queue_ptr
    mov    [bx].event_error,NO_ERROR    ;assume that all was okay.
    jnc    our_isr_1
    mov    [bx].event_error,dh    ;it wasn't.
our_isr_1:
    ret


their_recv    dd    ?

our_recv:
    assume    ds:nothing
    mov    saved_ds,ds
    mov    saved_bx,bx
    mov    saved_ax,ax
    cld

    mov    bx,cs            ;set up ds.
    mov    ds,bx
    assume    ds:code

    or    ax,ax            ;first call or second?
    je    our_recv_first

    mov    bx,(size handle_struc)
    add    bx,cx
    call    queue_advance
    mov    [bx].event_function,EVENT_RECEIVE    ;not a real function.
    mov    [bx].event_error,0        ;no errors possible.
    mov    ax,saved_bx
    mov    [bx].event_handle,ax    ;remember which handle it was.

    push    cx
    push    si
    push    di
    push    ds
    push    es
    lea    di,[bx] + (size handle_struc)
    mov    ax,cs
    mov    es,ax
    mov    ds,saved_ds
    rep    movsb
    pop    es
    pop    ds
    pop    di
    pop    si
    pop    cx

    jmp    short our_recv_done
our_recv_first:
;ignore the first upcall.
our_recv_done:
    mov    ax,saved_ax
    mov    bx,saved_bx
    mov    ds,saved_ds        ;restore the two registers we destroyed.
    assume    ds:nothing

    jmp    their_recv
    assume    ds:code


queue_advance:
;enter with bx = number of bytes that we require in the queue.
;exit with bx,queue_ptr set to a pointer to our entry.
;preserve everything but ds, bx, and the flags.
queue_advance_3:
    mov    ax,queue_tail
    add    ax,bx
    cmp    ax,queue_head        ;if we don't overlap the head, we're
    jbe    queue_advance_1        ;  okay.

    xchg    bx,queue_head        ;get queue_head and save bx.
    add    bx,[bx].event_length
    cmp    bx,queue_end        ;see if we hit the end.
    xchg    queue_head,bx        ;store queue_head and restore bx.
    jb    queue_advance_3        ;if we're less than the end, continue.
;we have to wrap here.
    push    bx
    mov    bx,queue_tail
    mov    ax,queue_end        ;make an event length that's too large.
    sub    ax,offset queue_begin
    mov    [bx].event_length,ax
    mov    bx,offset queue_begin    ;and restart from the beginning.
    mov    queue_tail,bx        ;ensure that we nuke some more.
    mov    queue_head,bx
    pop    bx
    jmp    queue_advance_3
queue_advance_1:
    xchg    ax,queue_tail        ;update the tail and get this ptr.
    mov    queue_ptr,ax        ;save this pointer.
    xchg    ax,bx
    mov    [bx].event_length,ax    ;store the length of this entry here.

    mov    ah,saved_ah        ;store their function value.
    mov    [bx].event_function,ah

;remember when it happened.
    push    dx
    push    ds
    mov    ax,40h
    mov    ds,ax
    mov    ax,ds:6ch        ;get the timer tick count.
    mov    dx,ds:6eh
    pop    ds
    mov    [bx].event_time+0,ax
    mov    [bx].event_time+2,dx
    pop    dx

    ret


copyleft_msg    label    byte
 db "Packet driver tracer version ",'0'+(majver / 10),'0'+(majver mod 10),'.',version+'0'," copyright 1988-92, Russell Nelson.",CR,LF
 db "This program is free software; see the file COPYING for details.",CR,LF
 db "NO WARRANTY; see the file COPYING for details.",CR,LF
crlf_msg    db    CR,LF,'$'

entry_point_name    db    "Packet interrupt number ",'$'
buffer_size_name    db    "Buffer size ",'$'

before_exec_msg    db    "Now run your network software and type 'exit' when finished",CR,LF,'$'
run_dump_msg    db    "Now run 'dump' to interpret 'trace.out'",CR,LF,'$'

disk_full_msg    db    "Disk Full!",'$'

already_msg    db    CR,LF,"There is no packet driver at ",'$'
packet_int_msg    db    CR,LF
        db    "Error: <packet_int_no> should be in the range 0x60 to 0x80"
        db    '$'

usage_msg    db    "usage: trace entry_point <buffer_size>",'$'

queue_error_msg    db    "Error: <buffer_size> should be larger than 2000 and less than 64000",'$'

trace_out    db    "TRACE.OUT",0    ;filename that we write the dump to.

usage_error:
    mov    dx,offset usage_msg
error:
    mov    ah,9
    int    21h
    int    20h

already_error:
    mov    dx,offset already_msg
    mov    di,offset entry_point
    call    print_number
    int    20h

start_1:
    mov    sp,offset stack

    mov    dx,offset copyleft_msg
    mov    ah,9
    int    21h

    mov    si,offset phd_dioa+1
    cmp    byte ptr [si],CR    ;end of line?
    je    usage_error

    mov    di,offset entry_point    ;parse the packet interrupt number
    call    get_number        ;  for them.

    mov    di,offset queue_length    ;parse the packet interrupt number
    call    get_number        ;  for them.

    cmp    byte ptr [si],CR    ;end of line?
    jne    usage_error

    cmp    queue_length+2,0
    jne    start_3
    cmp    queue_length,2000
    ja    start_2
start_3:
    mov    dx,offset queue_error_msg
    jmp    error
start_2:

    mov    di,offset entry_point    ;parse the packet interrupt number
    mov    dx,offset entry_point_name
    call    print_number        ;  for them.

    mov    di,offset queue_length    ;parse the packet interrupt number
    mov    dx,offset buffer_size_name
    call    print_number        ;  for them.

;initialize the queue
    mov    bx,offset queue_begin
    mov    queue_tail,bx
    add    bx,queue_length
    mov    queue_end,bx        ;initialize the head of the queue.
    mov    [bx].event_length,1    ;anything >0 will ensure that we're >end.
    mov    queue_head,bx

;do some error checking.
    cmp    entry_point,60h    ;make sure that the packet interrupt
    jae    pkt_int_ok        ;  number is in range.
    cmp    entry_point,80h
    jbe    pkt_int_ok
    mov    dx,offset packet_int_msg
    jmp    error
pkt_int_ok:

    mov    al,entry_point    ;is there a packet driver there?
    call    chk_int
    je    start_4            ;yes, so we can trace it.
    jmp    already_error        ;no, give them an error.
start_4:
    mov    their_isr.offs,bx
    mov    their_isr.segm,es

    mov    ah,25h            ;install our packet interrupt
    mov    dx,offset our_isr
    int    21h

    mov    dx,offset before_exec_msg
    mov    ah,9
    int    21h

;
; Now free the memory we don't need.
;
    mov    bx,queue_end
    add    bx,size event_struc    ;leave room for one more.
    add    bx,0fh            ;round up to next highest paragraph.
    mov    cl,4
    shr    bx,cl
    movseg    es,cs
    mov    ah,4ah
    int    21h

; Now we execute command.com

    mov    ax,cs
    mov    word ptr parm2+2,ax
    mov    word ptr parm3+2,ax
    mov    word ptr parm4+2,ax

    mov    si,offset their_dioa+1    ;re-parse the two fcbs.
    mov    di,offset phd_fcb1
    movseg    es,ds
    mov    ax,2901h
    int    21h

    mov    di,offset phd_fcb2
    mov    ax,2901h
    int    21h

    mov    si,offset comspec_env_str    ;see if this is the one.
    mov    cx,comspec_env_len
    call    getenv

    mov    si,offset program
copyname:
    mov    al,es:[di]
    mov    ds:[si],al
    inc    si
    inc    di
    or    al,al
    jne    copyname

    movseg    es,cs

    mov    ah,4bh
    mov    bx,offset parm
    mov    dx,offset program
    mov    al,0
    int    21h

    mov    bx,cs            ;restore our segment registers.
    mov    ds,bx
    mov    es,bx
    mov    ss,bx
    mov    sp,offset stack

; Give up our packet interception.

    mov    al,entry_point    ;release our_isr.
    mov    ah,25h
    push    ds
    lds    dx,their_isr
    int    21h
    pop    ds

; Now we write our captured information out to disk.

    mov    dx,offset trace_out    ;create "trace.out".
    mov    ah,3ch
    mov    cx,0
    int    21h

    mov    bx,ax

    mov    si,queue_head
write_out:
    mov    dx,si
    mov    cx,[si].event_length    ;write this event out.
    add    si,cx            ;is this the end of the queue?
    cmp    si,queue_end        ;
    ja    write_out_1

    mov    ah,40h
    int    21h
    cmp    ax,cx
    jne    write_out_full

    jmp    write_out

write_out_1:
    mov    si,offset queue_begin    ;yes.
write_out_2:
    cmp    si,queue_tail        ;quit when we hit the tail.
    jae    write_out_3

    mov    dx,si            ;set dx for the file write below.
    mov    cx,[si].event_length    ;write this event out.
    add    si,cx

    mov    ah,40h
    int    21h
    cmp    ax,cx
    jne    write_out_full

    jmp    write_out_2
write_out_3:
    mov    ah,3eh            ;close the file.
    int    21h

    mov    dx,offset run_dump_msg
    mov    ah,9
    int    21h

    int    20h

write_out_full:
    mov    ah,9
    mov    dx,offset disk_full_msg
    int    21h
    int    20h


    include    intchk.asm
    include    getnum.asm
    include    printnum.asm
    include    skipblk.asm
    include    getdig.asm
    include    decout.asm
    include    digout.asm
    include    chrout.asm
    include    getenv.asm
    include    crlf.asm

end_code    label    byte

queue_begin    label    byte

code    ends

    end    start