mirror of
https://github.com/microsoft/MS-DOS.git
synced 2024-11-25 23:25:47 +00:00
788 lines
23 KiB
NASM
788 lines
23 KiB
NASM
;
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||
; This version of COMMAND is divided into three distinct parts. First is the
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||
; resident portion, which includes handlers for interrupts 22H (terminate),
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; 23H (Cntrl-C), 24H (fatal error), and 27H (stay resident); it also has code
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; to test and, if necessary, reload the transient portion. Following the
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; resident is the init code, which is overwritten after use. Then comes the
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; transient portion, which includes all command processing (whether internal
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; or external). The transient portion loads at the end of physical memory,
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; and it may be overlayed by programs that need as much memory as possible.
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; When the resident portion of command regains control from a user program, a
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; checksum is performed on the transient portion to see if it must be
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; reloaded. Thus programs which do not need maximum memory will save the time
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; required to reload COMMAND when they terminate.
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;
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; REV 1.17
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; 05/19/82 Fixed bug in BADEXE error (relocation error must return to
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; resident since the EXELOAD may have overwritten the transient.
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; REV 1.18
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; 05/21/82 IBM version always looks on drive A
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; MSVER always looks on default drive
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;
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; REV 1.19
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; 06/03/82 Drive spec now entered in command line
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; 06/07/82 Added VER command (print DOS version number) and VOL command
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; (print volume label)
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; REV 1.20
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; 06/09/82 Prints "directory" after directories
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; 06/13/82 MKDIR, CHDIR, PWD, RMDIR added
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; REV 1.50
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; Some code for new 2.0 DOS, sort of HACKey. Not enough time to
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; do it right.
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; REV 1.70
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; EXEC used to fork off new processes
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; REV 1.80
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; C switch for single command execution
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; REV 1.90
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; Batch uses XENIX
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; Rev 2.00
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; Lots of neato stuff
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; IBM 2.00 level
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; Rev 2.01
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; 'D' switch for date time suppression
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; Rev 2.02
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; Default userpath is NUL rather than BIN
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; same as IBM
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; COMMAND split into pieces
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; Rev 2.10
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; INTERNATIONAL SUPPORT
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; Rev 2.11 COMMAND split into more pieces
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INCLUDE DOSSYM.ASM
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INCLUDE DEVSYM.ASM
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INCLUDE COMSW.ASM
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INCLUDE COMEQU.ASM
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CODERES SEGMENT PUBLIC
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CODERES ENDS
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DATARES SEGMENT PUBLIC BYTE
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EXTRN COMBAD:BYTE,NEEDCOM:BYTE,DRVMSG:BYTE
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EXTRN DEFMSG:BYTE,PROMPT:BYTE,EXECEMES:BYTE,EXEBAD:BYTE
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EXTRN TOOBIG:BYTE,NOCOM:BYTE,RBADNAM:BYTE,INT_2E_RET:DWORD
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EXTRN NOHANDMES:BYTE,BMEMMES:BYTE,HALTMES:BYTE,FRETMES:BYTE
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EXTRN PARENT:WORD,HANDLE01:WORD,LOADING:BYTE,BATCH:WORD
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EXTRN TRNSEG:WORD,COMDRV:BYTE,MEMSIZ:WORD,SUM:WORD,EXTCOM:BYTE
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EXTRN IO_SAVE:WORD,PERMCOM:BYTE,SINGLECOM:WORD,VERVAL:WORD
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EXTRN PIPEFLAG:BYTE,SAVE_PDB:WORD,COMSPEC:BYTE,TRANS:WORD
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EXTRN TRANVARS:BYTE,LTPA:WORD,RSWITCHAR:BYTE,RDIRCHAR:BYTE
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EXTRN RETCODE:WORD,FORFLAG:BYTE
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IF IBMVER
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EXTRN SYS_CALL:DWORD,ZEXEC:WORD,EXESEG:WORD,EXESUM:WORD
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EXTRN USER_SS:WORD,USER_SP:WORD
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ENDIF
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DATARES ENDS
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ENVIRONMENT SEGMENT PUBLIC PARA ; Default COMMAND environment
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ENVIRONMENT ENDS
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INIT SEGMENT PUBLIC PARA
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EXTRN CONPROC:NEAR
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INIT ENDS
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TAIL SEGMENT PUBLIC PARA
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TAIL ENDS
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TRANCODE SEGMENT PUBLIC PARA
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TRANCODE ENDS
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TRANDATA SEGMENT PUBLIC BYTE
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EXTRN TRANDATAEND:BYTE
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TRANDATA ENDS
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TRANSPACE SEGMENT PUBLIC BYTE
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EXTRN TRANSPACEEND:BYTE,HEADCALL:DWORD
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TRANSPACE ENDS
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TRANTAIL SEGMENT PUBLIC PARA
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TRANTAIL ENDS
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ZEXEC_CODE SEGMENT PUBLIC PARA
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ZEXEC_CODE ENDS
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ZEXEC_DATA SEGMENT PUBLIC BYTE
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ZEXEC_DATA ENDS
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RESGROUP GROUP CODERES,DATARES,ENVIRONMENT,INIT,TAIL
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TRANGROUP GROUP TRANCODE,TRANDATA,TRANSPACE,TRANTAIL
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EGROUP GROUP ZEXEC_CODE,ZEXEC_DATA
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ENVIRONMENT SEGMENT PUBLIC PARA ; Default COMMAND environment
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PUBLIC ECOMSPEC,ENVIREND,PATHSTRING
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ORG 0
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ENVARENA DB 10H DUP (?) ; Pad for mem arena
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PATHSTRING DB "PATH="
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USERPATH LABEL BYTE
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DB 0 ; Null path
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DB "COMSPEC="
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ECOMSPEC DB "/COMMAND.COM"
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DB 134 DUP (0)
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ENVIREND LABEL BYTE
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ENVIRONSIZ EQU $-PATHSTRING
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ENVIRONSIZ2 EQU $-ECOMSPEC
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ENVIRONMENT ENDS
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; START OF RESIDENT PORTION
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CODERES SEGMENT PUBLIC
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PUBLIC GETCOMDSK2,LODCOM,THEADFIX,CONTCTERM,LOADCOM,INT_2E,LODCOM1
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PUBLIC CHKSUM,SETVECT,EXT_EXEC,TREMCHECK,RESTHAND,CONTC,RSTACK
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PUBLIC SAVHAND
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IF IBMVER
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PUBLIC EXECHK,SYSCALL,EXEC_WAIT
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ENDIF
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ASSUME CS:RESGROUP,DS:NOTHING,ES:NOTHING,SS:NOTHING
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EXTRN RPRINT:NEAR,ASKEND:NEAR,DSKERR:NEAR
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ORG 0
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ZERO = $
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ORG 100H
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PROGSTART:
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JMP RESGROUP:CONPROC
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DB (80H - 3) DUP (?)
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RSTACK LABEL WORD
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IF IBMVER
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SYSCALL:
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CMP AH,EXEC
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JZ do_exec
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JMP DWORD PTR [SYS_CALL]
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do_exec:
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PUSH ES
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PUSH DS
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PUSH BP
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PUSH DI
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PUSH SI
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PUSH DX
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PUSH CX
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PUSH BX
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PUSH AX
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MOV [user_ss],SS
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MOV [user_sp],SP
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;
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; are we running on RSTACK already?
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;
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PUSH CS
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POP BX ; BX <- CS
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PUSH SS
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POP AX ; AX <- SS
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CMP AX,BX ; IF AX == BX then no stack switch!
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JZ Get_mem
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MOV SS,BX
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ASSUME SS:RESGROUP
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MOV SP,OFFSET RESGROUP:RSTACK
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Get_mem:
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MOV BX,0FFFFH ; allocate all of memory
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MOV AH,ALLOC
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INT int_command
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MOV AX,OFFSET EGROUP:ZEXECDATAEND + 15
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MOV CL,4
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SHR AX,CL
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MOV CX,AX ; Save in CX
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CMP BX,AX ; enough for EXEC?
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JB EXECMER ; nope... cry
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MOV AH,ALLOC
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INT int_command
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JC EXECMER ; Memory arenas probably trashed
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ADD BX,AX
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MOV [MEMSIZ],BX
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SUB BX,CX
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MOV [EXESEG],BX ; exec
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MOV ES,AX
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MOV AH,DEALLOC
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INT int_command
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PUSH CS
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POP DS
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ASSUME DS:RESGROUP
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CALL EXECHK
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CMP DX,[EXESUM]
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JZ HAVEXEC ; EXEC OK
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MOV DX,OFFSET RESGROUP:COMSPEC
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MOV AX,OPEN SHL 8
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INT int_command ; Open COMMAND.COM
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JC EXECMER
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MOV BX,AX ; Handle
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MOV DX,OFFSET RESGROUP:TRANSTART
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ADD DX,OFFSET TRANGROUP:EXECSTART - 100H
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XOR CX,CX ; Seek loc
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MOV AX,LSEEK SHL 8
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INT int_command
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MOV CX,OFFSET EGROUP:ZEXECCODEEND
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MOV DS,[EXESEG]
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ASSUME DS:NOTHING
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MOV AH,READ
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INT int_command
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PUSH AX
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MOV AH,CLOSE
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INT int_command ; Close COMMAND.COM
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POP CX
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CMP CX,OFFSET EGROUP:ZEXECCODEEND
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JNZ EXECMER ; Size matched
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CALL EXECHK
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CMP DX,[EXESUM]
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JNZ EXECMER
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HAVEXEC:
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MOV [LOADING],0 ; Flag to DSKERR
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CALL DWORD PTR [ZEXEC]
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JMP SHORT EXECRET
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execmer:
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LDS SI,DWORD PTR [user_Sp]
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MOV [SI.user_AX],exec_not_enough_memory
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PUSH [SI.user_F]
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POPF
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STC
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PUSHF
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POP [SI.user_F]
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execret:
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MOV SS,[user_SS]
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ASSUME SS:NOTHING
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MOV SP,[user_SP]
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POP AX ; PUSH ES
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POP BX ; PUSH DS
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POP CX ; PUSH BP
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POP DX ; PUSH DI
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POP SI ; PUSH SI
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POP DI ; PUSH DX
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POP BP ; PUSH CX
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POP DS ; PUSH BX
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POP ES ; PUSH AX
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IRET
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EXECHK:
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ASSUME DS:NOTHING,ES:NOTHING,SS:NOTHING
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PUSH DS
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MOV DS,[EXESEG]
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MOV CX,OFFSET EGROUP:ZEXECCODEEND
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XOR SI,SI
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JMP CHECK_SUM
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ENDIF
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EXEC_ERR: ; Select the correct error message
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MOV DX,OFFSET RESGROUP:RBADNAM
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CMP AX,exec_file_not_found
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JZ GOTEXECEMES
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CMP AX,error_access_denied
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JZ GOTEXECEMES
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MOV DX,OFFSET RESGROUP:TOOBIG
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CMP AX,exec_not_enough_memory
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JZ GOTEXECEMES
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MOV DX,OFFSET RESGROUP:EXEBAD
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CMP AX,exec_bad_format
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JZ GOTEXECEMES
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MOV DX,OFFSET RESGROUP:EXECEMES
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GOTEXECEMES:
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PUSH CS
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POP DS
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CALL RPRINT
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JMP SHORT NOEXEC
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EXT_EXEC:
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;
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; we are now running in free space. anything we do from here
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; on may get trashed. Move the stack (also in free space) to
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; allocated space because since EXEC restores the stack,
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; somebody may trash what is on the stack.
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;
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MOV CX,CS
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MOV SS,CX
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MOV SP,OFFSET RESGROUP:RSTACK
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;
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; Oops!! We have to make sure that the EXEC code doesn't blop a newstack!
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;
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;
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INT int_command ; Do the EXEC
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JC EXEC_ERR ; EXEC failed
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EXEC_WAIT:
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MOV AH,WAIT
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INT int_command ; Get the return code
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MOV [RETCODE],AX
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NOEXEC:
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JMP LODCOM
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CONTC:
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STI
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MOV AX,CS
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MOV DS,AX
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ASSUME DS:RESGROUP
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MOV AH,DISK_RESET
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INT int_command ; Reset disks in case files were open
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TEST [BATCH],-1
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JZ CONTCTERM
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JMP ASKEND ; See if user wants to terminate batch
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CONTCTERM:
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XOR BP,BP ; Indicate no read
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MOV [FORFLAG],0 ; Turn off for processing
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MOV [PIPEFLAG],0 ; Turn off any pipe
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CMP [SINGLECOM],0 ; See if we need to set SINGLECOM
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JZ NOSETSING
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MOV [SINGLECOM],-1 ; Cause termination on pipe, batch, for
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NOSETSING:
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CMP [EXTCOM],0
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JNZ DODAB ; Internal ^C
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JMP LODCOM1
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DODAB:
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STC ; Tell DOS to abort
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ZZY PROC FAR
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RET ; Leave flags on stack
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ZZY ENDP
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BADMEMERR: ; Allocation error loading transient
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MOV DX,OFFSET RESGROUP:BMEMMES
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FATALC:
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PUSH CS
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POP DS
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CALL RPRINT
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CMP [PERMCOM],0
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JZ FATALRET
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CMP [SINGLECOM],0 ; If PERMCOM and SINGLECOM
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JNZ FATALRET ; Must take INT_2E exit
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MOV DX,OFFSET RESGROUP:HALTMES
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CALL RPRINT
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STALL:
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JMP STALL ; Crash the system nicely
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FATALRET:
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MOV DX,OFFSET RESGROUP:FRETMES
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CALL RPRINT
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FATALRET2:
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CMP [PERMCOM],0 ; If we get here and PERMCOM,
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JNZ RET_2E ; must be INT_2E
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IF IBM
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LDS DX,DWORD PTR [SYS_CALL]
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ASSUME DS:NOTHING
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MOV AX,(SET_INTERRUPT_VECTOR SHL 8) + INT_COMMAND
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INT int_command
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ENDIF
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MOV AX,[PARENT]
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MOV WORD PTR CS:[PDB_Parent_PID],AX
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MOV AX,(EXIT SHL 8) ; Return to lower level
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INT int_command
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RET_2E:
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PUSH CS
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POP DS
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ASSUME DS:RESGROUP,ES:NOTHING,SS:NOTHING
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MOV [SINGLECOM],0 ; Turn off singlecom
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MOV ES,[LTPA]
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MOV AH,DEALLOC
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INT int_command ; Free up space used by transient
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MOV BX,[SAVE_PDB]
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MOV AH,SET_CURRENT_PDB
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INT int_command ; Current process is user
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MOV AX,[RETCODE]
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CMP [EXTCOM],0
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JNZ GOTECODE
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XOR AX,AX ; Internals always return 0
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GOTECODE:
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MOV [EXTCOM],1 ; Force external
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JMP [INT_2E_RET] ;"IRET"
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INT_2E: ; Magic command executer
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ASSUME DS:NOTHING,ES:NOTHING,SS:NOTHING
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POP WORD PTR [INT_2E_RET]
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POP WORD PTR [INT_2E_RET+2] ;Get return address
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POP AX ;Chuck flags
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PUSH CS
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POP ES
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MOV DI,80H
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MOV CX,64
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REP MOVSW
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MOV AH,GET_CURRENT_PDB
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INT int_command ; Get user's header
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MOV [SAVE_PDB],BX
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MOV AH,SET_CURRENT_PDB
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MOV BX,CS
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INT int_command ; Current process is me
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MOV [SINGLECOM],81H
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MOV [EXTCOM],1 ; Make sure this case forced
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|
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LODCOM: ; Termination handler
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CMP [EXTCOM],0
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JZ LODCOM1 ; If internal, memory already allocated
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MOV BX,0FFFFH
|
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MOV AH,ALLOC
|
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INT int_command
|
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MOV AX,OFFSET TRANGROUP:TRANSPACEEND + 15
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MOV CL,4
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SHR AX,CL
|
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|
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IF IBM
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PUSH AX
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MOV AX,OFFSET EGROUP:ZEXECDATAEND + 15
|
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MOV CL,4
|
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SHR AX,CL
|
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POP CX
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ADD AX,CX
|
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ENDIF
|
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|
||
ADD AX,20H
|
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CMP BX,AX ; Is less than 512 byte buffer worth it?
|
||
JNC MEMOK
|
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BADMEMERRJ:
|
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JMP BADMEMERR ; Not enough memory
|
||
MEMOK:
|
||
MOV AH,ALLOC
|
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INT int_command
|
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JC BADMEMERRJ ; Memory arenas probably trashed
|
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MOV [EXTCOM],0 ; Flag not to ALLOC again
|
||
MOV [LTPA],AX ; New TPA is base just allocated
|
||
ADD BX,AX
|
||
MOV [MEMSIZ],BX
|
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|
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MOV AX,OFFSET TRANGROUP:TRANSPACEEND + 15
|
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MOV CL,4
|
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SHR AX,CL
|
||
|
||
IF IBM
|
||
PUSH AX
|
||
MOV AX,OFFSET EGROUP:ZEXECDATAEND + 15
|
||
MOV CL,4
|
||
SHR AX,CL
|
||
POP CX
|
||
ADD AX,CX
|
||
ENDIF
|
||
|
||
SUB BX,AX
|
||
MOV [TRNSEG],BX ; Transient starts here
|
||
LODCOM1:
|
||
MOV AX,CS
|
||
MOV SS,AX
|
||
ASSUME SS:RESGROUP
|
||
MOV SP,OFFSET RESGROUP:RSTACK
|
||
MOV DS,AX
|
||
ASSUME DS:RESGROUP
|
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CALL HEADFIX ; Make sure files closed stdin and stdout restored
|
||
XOR BP,BP ; Flag command ok
|
||
MOV AX,-1
|
||
XCHG AX,[VERVAL]
|
||
CMP AX,-1
|
||
JZ NOSETVER
|
||
MOV AH,SET_VERIFY_ON_WRITE ; AL has correct value
|
||
INT int_command
|
||
NOSETVER:
|
||
CMP [SINGLECOM],-1
|
||
JNZ NOSNG
|
||
JMP FATALRET2 ; We have finished the single command
|
||
NOSNG:
|
||
CALL SETVECT
|
||
|
||
IF IBMVER
|
||
CALL EXECHK ; Check exe loader
|
||
CMP DX,[EXESUM]
|
||
JNZ BOGUS_COM
|
||
ENDIF
|
||
|
||
CALL CHKSUM ; Check the transient
|
||
CMP DX,[SUM]
|
||
JZ HAVCOM ; Transient OK
|
||
BOGUS_COM:
|
||
MOV [LOADING],1 ; Flag DSKERR routine
|
||
CALL LOADCOM
|
||
CHKSAME:
|
||
|
||
IF IBMVER
|
||
CALL EXECHK
|
||
CMP DX,[EXESUM]
|
||
JNZ ALSO_BOGUS
|
||
ENDIF
|
||
|
||
CALL CHKSUM
|
||
CMP DX,[SUM]
|
||
JZ HAVCOM ; Same COMMAND
|
||
ALSO_BOGUS:
|
||
CALL WRONGCOM
|
||
JMP SHORT CHKSAME
|
||
HAVCOM:
|
||
MOV AX,CHAR_OPER SHL 8
|
||
INT int_command
|
||
MOV [RSWITCHAR],DL
|
||
CMP DL,'/'
|
||
JNZ USESLASH
|
||
MOV [RDIRCHAR],'\' ; Select alt path separator
|
||
USESLASH:
|
||
MOV [LOADING],0 ; Flag to DSKERR
|
||
MOV SI,OFFSET RESGROUP:TRANVARS
|
||
MOV DI,OFFSET TRANGROUP:HEADCALL
|
||
MOV ES,[TRNSEG]
|
||
CLD
|
||
MOV CX,8
|
||
REP MOVSW ; Transfer INFO to transient
|
||
MOV AX,[MEMSIZ]
|
||
MOV WORD PTR DS:[PDB_block_len],AX ; Adjust my own header
|
||
JMP DWORD PTR [TRANS]
|
||
|
||
; Far call to REMCHECK for TRANSIENT
|
||
TREMCHECK PROC FAR
|
||
CALL REMCHECK
|
||
RET
|
||
TREMCHECK ENDP
|
||
|
||
REMCHECK:
|
||
;All registers preserved. Returns zero if media removable, NZ if fixed
|
||
; AL is drive (0=DEF, 1=A,...)
|
||
IF IBM
|
||
PUSH AX
|
||
OR AL,AL
|
||
JNZ GOTDRV2
|
||
MOV AH,GET_DEFAULT_DRIVE
|
||
INT int_command
|
||
INC AL ;A=1
|
||
GOTDRV2:
|
||
PUSH BX
|
||
MOV BL,AL
|
||
INT 11H ;IBM EQUIP CALL
|
||
ROL AL,1
|
||
ROL AL,1
|
||
AND AL,3
|
||
JNZ NOT_SINGLE
|
||
INC AL
|
||
NOT_SINGLE:
|
||
INC AL ; AL is now MAX floppy #
|
||
CMP BL,AL
|
||
POP BX
|
||
JBE SETREM ; Is an IBM floppy and so is removable
|
||
OR AL,AL ; Know AL is non-zero
|
||
JMP SHORT SETNREM
|
||
SETREM:
|
||
ELSE
|
||
PUSH AX
|
||
ENDIF
|
||
|
||
XOR AX,AX ;Zero
|
||
|
||
IF IBM
|
||
SETNREM:
|
||
ENDIF
|
||
|
||
POP AX
|
||
RET
|
||
|
||
; Far call to HEADFIX for TRANSIENT
|
||
THEADFIX PROC FAR
|
||
CALL HEADFIX
|
||
RET
|
||
THEADFIX ENDP
|
||
|
||
HEADFIX:
|
||
XOR BX,BX ; Clean up header
|
||
MOV CX,[IO_SAVE]
|
||
MOV DX,WORD PTR DS:[PDB_JFN_Table]
|
||
CMP CL,DL
|
||
JZ CHK1 ; Stdin matches
|
||
MOV AH,CLOSE
|
||
INT int_command
|
||
MOV DS:[PDB_JFN_Table],CL ; Restore stdin
|
||
CHK1:
|
||
INC BX
|
||
CMP CH,DH ; Stdout matches
|
||
JZ CHKOTHERHAND
|
||
MOV AH,CLOSE
|
||
INT int_command
|
||
MOV DS:[PDB_JFN_Table+1],CH ; Restore stdout
|
||
CHKOTHERHAND:
|
||
ADD BX,4 ; Skip 2,3,4
|
||
MOV CX,FilPerProc - 5 ; Already done 0,1,2,3,4
|
||
CLOSELOOP:
|
||
MOV AH,CLOSE
|
||
INT int_command
|
||
INC BX
|
||
LOOP CLOSELOOP
|
||
RET
|
||
|
||
SAVHAND:
|
||
ASSUME DS:NOTHING,ES:NOTHING,SS:NOTHING
|
||
PUSH DS
|
||
PUSH BX ; Set stdin to sterr, stdout to stderr
|
||
PUSH AX
|
||
MOV AH,GET_CURRENT_PDB
|
||
INT int_command ; Get user's header
|
||
MOV DS,BX
|
||
MOV AX,WORD PTR DS:[PDB_JFN_Table]
|
||
MOV [HANDLE01],AX ; Save user's stdin, stdout
|
||
MOV AL,DS:[PDB_JFN_Table+2]
|
||
MOV AH,AL
|
||
MOV WORD PTR DS:[PDB_JFN_Table],AX ; Dup stderr
|
||
POP AX
|
||
POP BX
|
||
POP DS
|
||
RET
|
||
|
||
ASSUME DS:RESGROUP
|
||
GETCOMDSK2:
|
||
CALL GETCOMDSK
|
||
JMP LODCOM1 ; Memory already allocated
|
||
|
||
RESTHAND:
|
||
PUSH DS
|
||
PUSH BX ; Restore stdin, stdout to user
|
||
PUSH AX
|
||
MOV AH,GET_CURRENT_PDB
|
||
INT int_command ; Point to user's header
|
||
MOV AX,[HANDLE01]
|
||
MOV DS,BX
|
||
ASSUME DS:NOTHING
|
||
MOV WORD PTR DS:[PDB_JFN_Table],AX ; Stuff his old 0 and 1
|
||
POP AX
|
||
POP BX
|
||
POP DS
|
||
RET
|
||
ASSUME DS:RESGROUP,SS:RESGROUP
|
||
|
||
HOPELESS:
|
||
MOV DX,OFFSET RESGROUP:NOCOM
|
||
JMP FATALC
|
||
|
||
GETCOMDSK:
|
||
MOV DX,OFFSET RESGROUP:NEEDCOM
|
||
GETCOMDSK3:
|
||
MOV AL,[COMDRV]
|
||
CALL REMCHECK
|
||
JNZ HOPELESS ;Non-removable media
|
||
CALL RPRINT
|
||
MOV DX,OFFSET RESGROUP:DRVMSG
|
||
CMP [COMDRV],0
|
||
JNZ GETCOM1
|
||
MOV DX,OFFSET RESGROUP:DEFMSG
|
||
GETCOM1:
|
||
CALL RPRINT
|
||
MOV DX,OFFSET RESGROUP:PROMPT
|
||
CALL RPRINT
|
||
CALL GetRawFlushedByte
|
||
RET
|
||
|
||
; flush world and get raw input
|
||
GetRawFlushedByte:
|
||
MOV AX,(STD_CON_INPUT_FLUSH SHL 8) OR RAW_CON_INPUT
|
||
INT int_command ; Get char without testing or echo
|
||
MOV AX,(STD_CON_INPUT_FLUSH SHL 8) + 0
|
||
INT int_command
|
||
return
|
||
|
||
LOADCOM: ; Load in transient
|
||
INC BP ; Flag command read
|
||
MOV DX,OFFSET RESGROUP:COMSPEC
|
||
MOV AX,OPEN SHL 8
|
||
INT int_command ; Open COMMAND.COM
|
||
JNC READCOM
|
||
CMP AX,open_too_many_open_files
|
||
JNZ TRYDOOPEN
|
||
MOV DX,OFFSET RESGROUP:NOHANDMES
|
||
JMP FATALC ; Fatal, will never find a handle
|
||
|
||
TRYDOOPEN:
|
||
CALL GETCOMDSK
|
||
JMP SHORT LOADCOM
|
||
|
||
READCOM:
|
||
MOV BX,AX ; Handle
|
||
MOV DX,OFFSET RESGROUP:TRANSTART
|
||
XOR CX,CX ; Seek loc
|
||
MOV AX,LSEEK SHL 8
|
||
INT int_command
|
||
JC WRONGCOM1
|
||
MOV CX,OFFSET TRANGROUP:TRANSPACEEND - 100H
|
||
|
||
IF IBM
|
||
ADD CX,15
|
||
AND CX,0FFF0H
|
||
ADD CX,OFFSET EGROUP:ZEXECCODEEND
|
||
ENDIF
|
||
|
||
PUSH DS
|
||
MOV DS,[TRNSEG]
|
||
ASSUME DS:NOTHING
|
||
MOV DX,100H
|
||
MOV AH,READ
|
||
INT int_command
|
||
POP DS
|
||
ASSUME DS:RESGROUP
|
||
WRONGCOM1:
|
||
PUSHF
|
||
PUSH AX
|
||
MOV AH,CLOSE
|
||
INT int_command ; Close COMMAND.COM
|
||
POP AX
|
||
POPF
|
||
JC WRONGCOM ; If error on READ
|
||
CMP AX,CX
|
||
JZ RET10 ; Size matched
|
||
WRONGCOM:
|
||
MOV DX,OFFSET RESGROUP:COMBAD
|
||
CALL GETCOMDSK3
|
||
JMP SHORT LOADCOM ; Try again
|
||
|
||
CHKSUM: ; Compute transient checksum
|
||
PUSH DS
|
||
MOV DS,[TRNSEG]
|
||
MOV SI,100H
|
||
MOV CX,OFFSET TRANGROUP:TRANDATAEND - 100H
|
||
|
||
CHECK_SUM:
|
||
CLD
|
||
SHR CX,1
|
||
XOR DX,DX
|
||
CHK:
|
||
LODSW
|
||
ADD DX,AX
|
||
LOOP CHK
|
||
POP DS
|
||
RET10: RET
|
||
|
||
SETVECT: ; Set useful vectors
|
||
MOV DX,OFFSET RESGROUP:LODCOM
|
||
MOV AX,(SET_INTERRUPT_VECTOR SHL 8) OR 22H ; Set Terminate address
|
||
INT int_command
|
||
MOV DX,OFFSET RESGROUP:CONTC
|
||
MOV AX,(SET_INTERRUPT_VECTOR SHL 8) OR 23H ; Set Ctrl-C address
|
||
INT int_command
|
||
MOV DX,OFFSET RESGROUP:DSKERR
|
||
MOV AX,(SET_INTERRUPT_VECTOR SHL 8) OR 24H ; Set Hard Disk Error address
|
||
INT int_command
|
||
RET
|
||
|
||
CODERES ENDS
|
||
|
||
; This TAIL segment is used to produce a PARA aligned label in the resident
|
||
; group which is the location where the transient segments will be loaded
|
||
; initial.
|
||
|
||
TAIL SEGMENT PUBLIC PARA
|
||
ORG 0
|
||
TRANSTART LABEL WORD
|
||
TAIL ENDS
|
||
|
||
; This TAIL segment is used to produce a PARA aligned label in the transient
|
||
; group which is the location where the exec segments will be loaded
|
||
; initial.
|
||
|
||
TRANTAIL SEGMENT PUBLIC PARA
|
||
ORG 0
|
||
EXECSTART LABEL WORD
|
||
TRANTAIL ENDS
|
||
|
||
IF IBMVER
|
||
INCLUDE EXEC.ASM
|
||
ENDIF
|
||
|
||
END PROGSTART
|
||
|