381 lines
11 KiB
NASM
381 lines
11 KiB
NASM
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;
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; Initialize the runtime environment.
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; The block at $$Link$$ contains parameters passed from
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; the linker.
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;
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; Determine memory bounds. Create stack and heap. Initialize
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; fundamental parameters.
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;
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;
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BUFSIZ EQU >200
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FALSE EQU 0
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TRUE EQU ~FALSE
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ENVIR EQU >2C
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DOS EQU >21
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MARGIN EQU >80
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OP$EXIT EQU >4C
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OP$PMSG EQU >09
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OP$VERS EQU >30
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OP$TIME EQU >2C
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OP$DATE EQU >2A
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CMDLINE EQU >80
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CMDLENGTH EQU >80
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ARGV0LEN EQU 64
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LONGNAME EQU >FFFF
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SHORTNAM EQU >FFFF
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CASE TRUE
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;
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IDT $_INIT_$
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DEF $_INIT_$
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DEF $_init_$
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DEF $$RETURN
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$_init_$ equ $
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$_INIT_$ MOV AX,DS
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MOV ES,AX
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MOV BX,SS
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MOV DS,BX
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MOV [$$PSP],AX
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SEGES
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MOV AX,[ENVIR]
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MOV [$$ENVIR],AX
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MOV AH,OP$VERS ; Dos version number
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INT DOS
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MOV [_osmajor],AX
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CMP AL,3 ; If 3.0 or greater
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JB GETTIME
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MOV ES,[$$ENVIR] ; scan environment for argv[0]
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XOR DI,DI
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MOV AL,%0
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MOV CX,-1
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CLD
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ENVNEXT SEGES
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CMP %[DI],%0 ; end of table?
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JZ ENDENV
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REPNZ
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SCASB
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JMPS ENVNEXT
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ENDENV INC DI ; skip terminator
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SEGES
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CMP [DI],1
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JNZ GETTIME ; no argv[0]
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ADD DI,%2
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MOV SI,$$ARGV0
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MOV CX,ARGV0LEN/2
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CPYARG0 SEGES
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MOV AX,[DI]
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MOV [SI],AX
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ADD DI,%2
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ADD SI,%2
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LOOP CPYARG0
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GETTIME MOV AH,OP$DATE
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INT DOS
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MOV [$$CLOCK],CX
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MOV [$$CLOCK2],DX
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MOV AH,OP$TIME
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INT DOS
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MOV [$$CLOCK4],CX
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MOV [$$CLOCK6],DX
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MOV ES,[$$PSP]
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SEGES
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MOV SI,[2] ; Top of available memory
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MOV [$$MAXSEG],SI
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MOV DX,DS
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SUB SI,DX
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CMP SI,>1000 ; More than 64k available?
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JAE DS64K
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MOV CL,4
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SHL SI,CL
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DEC SI
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JMPS DSSET
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DS64K MOV SI,>FFFF
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DSSET MOV BX,[DSSIZE] ; Size of initialized data
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ADD BX,MARGIN
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MOV [$$LIMIT],BX ; Lower limit of stack
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MOV AX,[STKSIZE]
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TEST AX,AX ; Zero means default
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JNZ STACKVAL
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MOV AX,[HPSIZE] ; Check heap size
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TEST AX,AX
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JNZ HPSET
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MOV AX,SI
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SUB AX,BX
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SHR AX,1 ; Half of memory for stack
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SUB AX,2
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AND AX,>FFFE
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MOV [STKSIZE],AX
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MOV [HPSIZE],AX
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JMPS STACKSET
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STACKVAL TEST [HPSIZE],>FFFF
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JNZ STACKSET
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MOV CX,SI
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SUB CX,AX
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JB NOMEM1
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SUB CX,BX
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JB NOMEM1
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DEC CX
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JB NOMEM1
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AND CX,>FFFE
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MOV [HPSIZE],CX
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JMPS STACKSET
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HPSET MOV CX,SI
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SUB CX,AX
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JB NOMEM1
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SUB CX,BX
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JB NOMEM1
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DEC CX
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AND CX,>FFFE
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JNB MEMOK
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NOMEM1 JMP NOMEM
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MEMOK MOV [STKSIZE],CX
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MOV AX,CX
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STACKSET ADD BX,AX
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JB NOMEM1
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CMP BX,SI ; Enough memory available
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JA NOMEM1
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MOV [$$BOTTOM],BX ; Top limit of stack
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MOV [$$MAXS],BX ; Maximum stack used
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INC BX
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AND BX,>FFFE
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POP AX ; Copy return address
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POP CX ; to new stack
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MOV SP,BX ; Set stack location for program
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MOV DX,CS
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PUSH DX ; Set final return address
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MOV [$$RETIS],DX
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MOV DX,$$RETURN
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PUSH DX
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MOV [$$RETI],DX
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MOV BP,SP ; Initial frame
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PUSH CX ; Save return to program
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PUSH AX
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MOV AX,DS ; initialize to zero
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MOV ES,AX
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MOV DI,[$$LIMIT]
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MOV CX,SP
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SUB CX,256
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SUB CX,DI
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SHR CX,1
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XOR AX,AX
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REP
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STOSW
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;
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; Create heap
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;
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INC BX ; Start heap on word boundary
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AND BX,>0FFFE
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MOV [$$HMIN],BX
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XOR AX,AX
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MOV [$$CURH],AX ; No heap used
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MOV [$$MAXH],AX
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ADD BX,[HPSIZE]
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JZ ALLMEM
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JB NOMEM1
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JMPS MAKEHEAP
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ALLMEM MOV BX,>FFFE
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MAKEHEAP AND BX,>FFFE ; Make top of heap a word boundary
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MOV [$$HMAX],BX ; STORE HEAP LIMIT
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MOV AX,BX
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DEC AX ; round up with top-16+15
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MOV CL,4
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SHR AX,CL
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INC AX ; add back the 16
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MOV DX,DS
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ADD AX,DX
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MOV [$$TOPSEG],AX ; First unused extra memory
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MOV [$$ENDDS],AX ; Segment of end of ds
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SUB AX,DX
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SHL AX,CL
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MOV [$$TOPDS],AX ; Top of data segment
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ADD BX,-6 ; RESERVE DUMMY PACKET
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MOV CX,BX ; SAVE POINTER TO DUMMY
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MOV DX,BX ; SAVE POINTER TO DUMMY
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MOV [BX],0 ; LENGTH OF DUMMY PACKET
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MOV AX,[$$HMIN] ; AX=ADDRESS OF INITIAL HEAP
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MOV [BX][%2],AX ; SET NEXT PACKET PTR
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MOV [BX][%4],AX ; SET PREDECESSOR PTR
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;
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; SET LENGTH OF INITIAL HEAP PACKET
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;
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SUB CX,AX ; CALCULATE HEAP SIZE
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MOV [$$FREE],AX
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MOV BX,AX ; POINT TO BIG HEAP PACKET
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MOV [BX],CX ; SET HEAP SIZE
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MOV [BX][%2],DX ;NEXT IS DUMMY PACKET
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MOV [BX][%4],DX ;PREDECESSOR IS DUMMY PACKET
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;
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; COPY COMMAND LINE TO DATA SEGMENT
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;
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MOV SI,CMDLINE
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MOV ES,[$$PSP]
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SEGES
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MOV CL,[SI] ; Length of command line
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CMP CL,5
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JB COPYALL ; Too short for trace
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SEGES
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CMP %[SI][%1],%>0D
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JNZ COPYALL ; Not trace
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SEGES
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MOV AX,[SI][%2]
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MOV [$$XTRC],AX
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SEGES
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MOV AX,[SI][%4]
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MOV [$$XTRC2],AX
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PUSH AX
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PUSH [$$XTRC]
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SUB CL,%5
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ADD SI,%5
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SEGES
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MOV %[SI],CL
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COPYALL MOV DI,$$CMDLIN
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MOV CX,CMDLENGTH/2
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MOV AX,DS
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MOV ES,AX
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MOV DS,[$$PSP]
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COPYCMD REP
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MOVSW
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MOV AX,ES
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MOV DS,AX
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MOV ES,[$$PSP]
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XOR BX,BX
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RETSEG
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;
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$$RETURN MOV AX,[$$EXSTAT]
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TEST AH,AH
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JZ STOP
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MOV AL,%>FF
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STOP CMP [$$XTRC2],0
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JZ NOTRC
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MOV BX,1
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CALLSEG [$$XTRC]
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NOTRC MOV AH,OP$EXIT
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INT DOS
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NOMEM MOV DX,NOMEMMSG
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MOV AH,OP$PMSG
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INT DOS
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MOV AL,%>FE
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JMPS STOP
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;
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; Data areas.
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; $$Link$$ contains information supplied by the linker.
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; $$PROCES contains control and status information used
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; by the program.
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;
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DORG 0
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;
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; Process control record. Contains status values, limits and
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; runtime flags
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;
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$$PROCES EQU $
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$$EXITPT DW $$RETI ; Exit address
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$$BOTTOM DW 0 ; Stack bottom (empty stack)
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$$LIMIT DW 0 ; Stack limit (full stack)
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$$HMIN DW 0 ; Lower bound of heap
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$$HMAX DW 0 ; Upper bound of heap
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$$FREE DW 0 ; Free space pointer for heap
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$$MAXS DW 0 ; Maximum stack used
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$$MAXH DW 0 ; Maximum heap used
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$$CURH DW 0 ; Current heap used
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$$IOTERM DB 0 ; Terminate on io error
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$$HPTERM DB 0 ; Terminate on heap full
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$$IOFLG DB 0 ; IO default flags
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$$ZFILL DB 0 ; Zero locals & heap packets flag
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$$FATAL DW 0 ; Fatal error address
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DW 0 ; Fatal error address (segment)
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$$CMDPTR DW $$CMDLIN ; Address of command line
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$$LIOERR DW 0 ; File for last io error
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_psp EQU $
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$$PSP DW 0 ; Program segment prefix segment
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$$ENVIR DW 0 ; Environment segment
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$$XTRC DW 0 ; Address of ctrace
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$$XTRC2 DW 0 ; Address of ctrace (segment)
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DW 0,0,0
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;
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errno DW 0 ; Error number
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_doserrn DW 0 ; Operating system error code
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$$FLERR DW 0 ; Floating point error code
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$$BUFSIZ DW BUFSIZ ; Default buffer size for files
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$$MAXSEG DW 0 ; First unavailable paragraph
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$$TOPSEG DW 0 ; First unused paragraph
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$$TOPDS DW 0 ; Top address in data segment
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$$ENDDS DW 0 ; Segment of end of data segment
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$$EXSTAT DW 0 ; Exit status
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$$MACHIN DB 0
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$$OPSYS DB >20
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$$SHMSG DB 0 ; Display statistics
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$$CLFEED DB 1 ; Filter line feeds (default)
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$$CCTLZ DB 0 ; Treat ctl/z as end of file (default)
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$$STATSV DB 0
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$$UBCON DB 0 ; Unbuffered console
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$$ARTERM DB 0 ; Terminate on arithmetic errors
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$$RETI DW 0 ; Far address of exit routine
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$$RETIS DW 0
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$$CMDLIN DS >80 ; Copy of command line
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_osmajor DB 0
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_osminor DB 0
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$$CLOCK DW 0
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$$CLOCK2 DW 0
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$$CLOCK4 DW 0
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$$CLOCK6 DW 0
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$$ARGV0 DB 0
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DS ARGV0LEN
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NOMEMMSG DB 'Not enough memory$'
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DDEF $$Link$$
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DORG 2*(($+1)/2)
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$$Link$$ EQU $
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STKSIZE DW 0 ; Stack size
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HPSIZE DW 0 ; Heap size
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DSSIZE DW 0 ; Size of initialized data
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DW 0,0,0,0,0 ; Filler for more parameters
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DW 0,0,0,0,0,0,0,0
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DDEF $$EXITPT
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DDEF $$BOTTOM
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DDEF $$LIMIT
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DDEF $$HMIN
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DDEF $$HMAX
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DDEF $$FREE
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DDEF $$MAXS
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DDEF $$MAXH
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DDEF $$CURH
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DDEF $$IOTERM
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DDEF $$HPTERM
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DDEF $$IOFLG
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DDEF $$ZFILL
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DDEF $$FATAL
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DDEF $$CMDPTR
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DDEF $$LIOERR
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DDEF $$PSP
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DDEF _psp
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DDEF $$ENVIR
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DDEF $$XTRC
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DDEF $$XTRC2
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DDEF errno
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IF SHORTNAM
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DDEF _doserrn
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ENDIF
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IF LONGNAME
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LDDEF _doserrno
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ENDIF
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DDEF $$FLERR
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DDEF $$BUFSIZ
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DDEF $$MAXSEG
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DDEF $$TOPSEG
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DDEF $$TOPDS
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DDEF $$ENDDS
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DDEF $$EXSTAT
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DDEF $$MACHIN
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DDEF $$OPSYS
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DDEF $$SHMSG
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DDEF $$CLFEED
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DDEF $$CCTLZ
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DDEF $$STATSV
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DDEF $$UBCON
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DDEF $$ARTERM
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DDEF $$RETI
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DDEF $$CMDLIN
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DDEF _osmajor
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DDEF _osminor
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DDEF $$CLOCK
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DDEF $$ARGV0
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END
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;
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