168 lines
4.9 KiB
NASM
168 lines
4.9 KiB
NASM
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;***************************************
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;* TIPC Scheme Runtime Support *
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;* *
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;* (C) Copyright 1985 by Texas *
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;* Instruments Incorporated. *
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;* All rights reserved. *
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;* *
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;* Date Written: 5 June 1985 *
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;* Last Modification: 15 May 1986 *
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;***************************************
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page 60,132
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.286c
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include smmu.mac
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MSDOS equ 021h ; MS-DOS service call interrupt
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BIDTASK equ 04Bh ; Load/Execute program
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DGROUP group data
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data segment word public 'DATA'
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assume DS:DGROUP
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extrn _psp:dword ; program segment prefix paragraph address
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cmd_ db "COMSPEC="
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cmd_1 equ $
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ENVPTR dw 0 ; DOS EXEC parameter block
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CMDOFF dw 0 ; "
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CMDSEG dw 0 ; "
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FCB1OFF dw 5Ch ; "
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FCB1SEG dw 0 ; "
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FCB2OFF dw 6Ch ; "
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FCB2SEG dw 0 ; "
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INSTALLED dw 0 ; Whether crt interrupt is installed or not
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data ends
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XGROUP group PROGX
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PROGX segment byte public 'PROGX'
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assume CS:XGROUP
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;************************************************************************
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;* Bid another Task *
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;************************************************************************
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;
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; BP is set up by bid (the caller of this routine)
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;
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bid_args struc
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dw ? ; caller's BP
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dw ? ; return address (caller of bid)
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bid_file dw ? ; program's file name
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bid_parm dw ? ; parameters
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free_req dw ? ; requested # of free paragraphs
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display dw ? ; Indicates if screen should be disturbed
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bid_args ends
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bid_task proc far
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push ES
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; Set up parameter block
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mov AX,[BP].bid_parm ; Set up dword pointer to command line
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mov CMDOFF,AX
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mov CMDSEG,DS
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mov AX,word ptr _psp+2 ; Point to FCBs in program segment prefix
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mov FCB1SEG,AX
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mov FCB2SEG,AX
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mov ES,AX
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mov AX,ES:[02Ch] ; copy current environment ptr to
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mov ENVPTR,AX ; parameter area
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; Set ES:BX to address of parameter block
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mov AX,DS
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mov ES,AX
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mov BX,offset ENVPTR
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; Set DS:DX to address of ASCIZ pathname (of file to be loaded)
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push DS ; save DS segment register
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mov DX,[BP].bid_file
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mov DI,DX
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cmp byte ptr [di],0 ; check if pt'ed to string is empty
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jne bid_it
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; No filename-- bid up a new command interpreter;
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; have to search environment for COMSPEC= string
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mov ES,ENVPTR ; ES:DI points to 1st string in environment
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xor DI,DI
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; Test for end of environment
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get_plop: cmp byte ptr ES:[DI],0 ; last entry in environment?
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je cmd_err ; if so, COMSPEC= not found
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mov SI,offset cmd_ ; load address of comparison string
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mov CX,cmd_1-cmd_ ; and length of same
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repe cmps cmd_,ES:[DI] ; does this entry begin "COMSPEC="?
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je found ; if so, found it! (jump)
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xor AX,AX ; clear AX for search
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mov CX,-1 ; set CX for maximum length
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repne scas byte ptr ES:[DI] ; find \0 which terminates string
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jmp get_plop ; loop
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; No command interpreter found
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cmd_err: mov AX,10 ; treat as bad-environment error
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stc
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jmp short get_out
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; Found COMSPEC=
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found: mov DX,DI ; DS:DX is ptr to command interpreter
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push DS ; (swap DS and ES)
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push ES
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pop DS
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pop ES
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; issue load task function call
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bid_it:
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xor AL,AL ; load and execute condition
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mov AH,BIDTASK
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; load "load and execute" ftn id
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int MSDOS ; perform service call
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get_out: pop DS ; restore DS segment register
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jc exit ; branch if error in bidding task
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xor AX,AX ; indicate no error
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exit:
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pop ES ; restore ES segment register
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ret ; return to caller
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bid_task endp
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PROGX ends
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PGROUP group prog
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prog segment byte public 'PROG'
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assume CS:PGROUP
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extrn unfixint:near,fix_intr:near
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extrn zcuron:near,zcuroff:near
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extrn set_crtint:near,reset_crtint:near
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public bid
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bid proc near
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push bp
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mov bp,sp ;address local arguments
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call unfixint ;reset shift-break vector
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call zcuron ;turn the cursor back on
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cmp [bp].display,0 ;can we disturb the screen?
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je no_install ; yes, jump
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call set_crtint ; no, take over crt interrupt
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no_install:
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call bid_task ;go bid the task
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push AX ;save its error return code
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cmp [bp].display,0 ;crt interrupt taken over
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je no_uninstall ; no, jump
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call reset_crtint ; yes, reset the crt interrupt
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no_uninstall:
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call zcuroff ;turn the cursor back off
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call fix_intr ;set shift-break vector
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pop AX ;restore error code
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pop bp ;dump args from stack
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ret ;return to caller
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bid endp
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prog ends
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end
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