Simtel MSDOS 1992 June/SIMTEL_0692.cdr/msdos/sysutl/env.arc/ENV.CMP

Text File | 1988-01-27 | 3.9 KB | 264 lines

n ENV.CMP for assembly by  DEBUG < ENV.CMP
n Purpose: pad/unpad the environment with ENVnn=
n env.com
f 100 500 c3
rcx
300

a 100
;100
 jmp 2c0
;103 env address
 db  00 00 'ee'
;107 envsize
 db 'ss'
;109 envtop
 db 'tt'
;10b envptr
 db 'pp'
;10d mod address
 db  80 00 'mm'
;111 pad/unpad
 db 00
;112 testline
 db 'unpad' 00
;118 found
 db 00

a 120
 push ds
;121                find top COMMAND.COM
 mov ax,[16]
 mov ds,ax
 cmp word ax,[16]
 jne 121
;12c                find its main environment
 dec ax
 mov ds,ax
 add word ax,[3]
 inc ax
 mov ds,ax
 mov word bx,[3]
 mov cl,4
 shl bx,cl
 inc ax
 pop ds
 mov [109],bx
 mov [107],bx        ;the length in bytes
 mov [105],ax        ;segenv
;now have env seg/ofs at [105]:[103]
 les di,[103]
 mov cx,[107]
 mov ax,0
;156 more repeats
 repne scasb
 dec cx
 scasb
 jne 156
 mov [10b],cx
 dec di
 mov [109],di
 ret

a 170
;170 string master for entry
 db 'ENV01=abcdefg' 0 0

a 180
;180                verify structure
 mov  cx,0
 add  cl,[80]
 je   1db            ;quit if no tail
 les  di,[10d]
 add  di,cx
 mov  ax,20
 std
 repe scasb
 je   1db            ;quit if all space
 inc  cx
 mov  di,81
 cld
 repe scasb
 inc  cx
 mov  [80],cl        ;length of trimmed string
 dec  di
 mov  [10d],di        ;posn of first char
 mov  al,[di]
 or   al,20
 mov  [111],al      ;record of first letter
 lds  si,[10d]
 mov  bp,113
 cmp  cl,3
 je   1c3
 mov  bp,111
 cmp  cl,5
 jne  1db
;1c3  loop
 lodsb
 inc  di
 inc  bp
 or   al,20
 cmp  al,[bp]
 loope 1c3
 jne  1db
 mov  ax,170
 mov  [10d],ax
 mov  al,[111]
 clc
 jmp  1dc
;1db not ok
 stc
;1dc exit
 ret

a 1df
;1df pad sequentially with ENV01, ENV02, until full
 call 200
 jc   1dc
 call 26e
 inc byte [174]
 cmp byte [174],3a
 jne 1df
 inc byte [173]
 mov al,30
 mov [174],al
 jmp 1df

a 200
;200 find size of present entry
 cld
 les  di,[10d]        ;find length of LHS
 mov  cx,di
 mov  al,3d
 repne scasb
 sub  di,cx
 ror  di,1
 dec  di
 mov  bx,di
;212                 search the environment for match
 mov  cx,[109]
 lds  si,[10d]
 les  di,[103]
 inc  si
;21f  loop for main search
 dec  si
 lodsb
 repne scasb
 push cx
 push si
 push di
 mov  cx,bx
 repe cmpsb
 pop di
 pop si
 pop cx
 jcxz 25f
 jne 21f
;231  search for end
 mov si,di
 mov bx,cx
 mov ax,0
 repne scasb
 sub bx,cx
 xchg si,di
 cs: mov ax,[109]
 sub ax,bx
 cs: add ax,F
 dec ax
 cs: cmp [107],ax
 jc  26a
 push es
 pop  ds
 dec  di
 inc  cx
 rep  movsb
 dec  di
 cs: mov [109],di
 clc
 jmp  26a
;25f
 push cs
 pop  ds
 mov  ax,di
 add  ax,F
 cmp  [107],ax
;26a
 ret

a 26e
;26e add new entry
 cs: mov cl,F
 cs: lds si,[10d]
 mov bx,cx
 rep movsb
 dec di
 mov [109],di
 ret

a 280
;280 unpad
 mov ax,[107]
 mov bx,e
 div bl
 inc ax
 mov [117],al
;28c unpad loop
 call 200
 push cs
 push cs
 pop  ds
 pop  es
 jnc  297
 jmp  2b1
;297
 inc byte [174]
 cmp byte [174],3a
 jne 2ab
 inc byte [173]
 mov al,30
 mov [174],al
;2ab
 dec byte [117]
 jne 28c
;2b1
 ret

a 2c0
;2c0            MAIN PROGRAMME
 mov  [10f],cs ;mod address for LDS/LES calls
 call 120      ;find envbase and envsize
 call 180      ;check validity of mod format
 jnc  2ce      ;if not valid ...
 jmp  2e0      ;... exit via syntax (err #1)
;2ce
 cmp  al,70    ;if not pad ...
 jne  2d7      ;... goto unpad
 call 1df      ;pad ...
 jmp  2da      ;... and exit
;2d7           ;unpad
 call 280
;2da           ;exit OK (err #0)
 mov  al,0
;2dc
 mov  ah,4c    ;standard exit from programme
 int21
;               END OF MAIN PROGRAMME

a 2e0
 mov  ah,9     ;print syntax and exit
 mov  dx,300
 int  21
 mov  al,1
 jmp  2dc

a 300
;300
 db 0a 0d 'Syntax: env pad|unpad' 0d 0a 24
 db '(C) 1988 Hylton Boothroyd, University of Warwick$' 0a 0d
 db 'Purpose: pad the environment with ENVnn variables,'0a 0d
 db 'or delete all ENVnn variables assumed to start with ENV01$'

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