Collection of Tools & Utilities

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Assembly Source File | 1988-05-23 | 6.5 KB | 265 lines

PAGE 55,130 ; SPCTAB ; bufspc equ 0400h stkspc equ 0100h midbuf equ 0200h codeseg segment assume cs:codeseg, ds:codeseg org 100h spctab proc far start: jmp init ; messages - errmsg1 db 0Dh, 0Ah, 'Read Error', 0Dh, 0Ah, '$' errmsg2 db 0Dh, 0Ah, 'Could not get enough memory.', 0Dh, 0Ah, '$' help_msg db 0Dh, 0Ah, 'SPCTAB is a filter that converts spaces' db ' in standard input to TABs in standard', 0Dh, 0Ah db 'output where possible. It also trims a line, that' db ' is, it deletes all trailing', 0Dh, 0Ah db 'spaces in a line.', 0Dh, 0Ah, 0Dh, 0Ah db 'Usage: SPCTAB [<fname] [>fname]', 0Dh, 0Ah, '$' errmsg3 db 0Dh, 0Ah, 'Write Error', 0Dh, 0Ah, '$' ; variables - count dw 0 ; Note - space for the 1024 byte buffer and the 256 byte stack is allocated ; here, rather than being stored in the task image on disk. ; init: mov bx,offset buffer + bufspc + stkspc ; req. mem. add bx,010h mov cl,4 shr bx,cl ; get it in paragraphs mov ah,04Ah ; set it - cf=1 if error int 021h mov dx,offset errmsg2 jc err_exit ; exit with error message mov ax,0 mov di,offset buffer ; else initialize buffer mov cx,bufspc + stkspc ; and stack space to 0 shr cx,1 ; (div by 2 for words) cld rep stosw mov sp,offset buffer + bufspc + stkspc ; init sp mov si,80h ; get cmd line char count cmp byte ptr [si],0 ; into cx and incr by 1 je Main mov cl,[si] inc cx skpspc: inc si ; skip any blanks cmp byte ptr [si],20h loopz skpspc jcxz Main ; skip if cmd line is all cmp byte ptr [si],3Fh ; spaces. Check for '?' jne Main ; ignore other chars mov dx,offset help_msg ; if '?' found, exit with jmp short err_exit ; 'help' message Main: call get_line ; get line from std input jc err_exit ; cf=1 is error or ax,ax jz norm_exit ; 0 char count is end call fix_line ; convert spcs to tabs call put_line ; write line to std output jc err_exit ; if cf=1, exit with err msg jmp short Main ; else continue. ; Note - here err_exit outputs the messages to std error rather than std ; out, so even if I/O is redirected from the cmd line, the message ; will be output to the console rather than the output file. err_exit: mov di,dx ; point di to error message mov cx,0FFh ; set cx to 255 ( countdown limit ) mov al,024h ; "$" cld repnz scasb ; incr di to message terminator dec di ; decr to last char of message mov cx,di ; arithmetic to get char count in cx sub cx,dx mov bx,2 ; handle for std error mov ah,040h ; output message int 021h mov al,1 ; exit status = 1 norm_exit: mov ah,04Ch int 021h spctab endp ; SUBROUTINE ; gets a line from std input get_line proc near mov si,offset buffer get_1: mov dx,si mov bx,0 ; handle for std input mov cx,1 mov ah,03Fh ; read cx chars int 021h jc get_err ; cf=1 if input error cmp byte ptr [si],0Ah ; eoln found je get_ok or ax,ax ; ax=0 if kybd input eof jz get_ok xor ax,ax ; (make ax=0 on eof) cmp byte ptr [si],1Ah ; eof found (disk file) je get_ok inc si jmp short get_1 get_ok: clc ret get_err: mov dx,offset errmsg1 stc ret get_line endp ; SUBROUTINE ; This is where the transformation takes place. ; Basically, you're on your own to understand this. ; fix_line proc near mov count,0 mov si,offset buffer mov di,offset buffer + midbuf xor bx,bx fix_loop_1: lodsb ; get a char (adv si) bigloop: cmp al,020h ; BL ? je fix_2 ; yes, next procedure. cmp al,0Dh ; CR ? jne fix_1a sub di,bx ; skip this if CR fix_1a: stosb ; not BL, not CR, so store it (adv di) cmp al,9 ; HT ? jne fix_1b ; if not, skip this add count,8 ; yes, add 8 to count and count,0FFF8h ; discard mod 8 remainder inc bx ; incr bx value jmp short fix_loop_1 ; continue fix_1b: inc count ; non-space char, incr count cmp al,0Ah ; check for NL je fix_done ; (exit this scene - line done.) xor bx,bx ; not NL, null bx value jmp short fix_loop_1 ; continue ; ---------- fix_2: push bx ; point bx to first BL input mov bx,si dec bx fix_3: lodsb ; while char is BL, cont to get cmp al,020h je fix_3 mov dx,si ; point dx to last BL input dec dx sub dx,bx ; subtract bx to get # of BL's mov ax,count ; put count in ax and bx mov bx,ax add ax,8 ; advance ax to next TS and ax,0FFF8h sub ax,bx ; subtract pos of 1st BL in series pop bx ; restore old bx value xor cx,cx ; null cx cmp dx,ax jb fix_4 ; dx hasn't reached next TS yet add count,ax ; dx reached next TS, add ax to count mov bx,1 ; set bx value to 1 sub dx,ax ; move pointer back ax BL's mov al,9 ; output a Tab char. stosb ; (di is keeping track here) mov cx,dx ; put dx value in cx shr cx,1 ; and divide by 8 (# of TS's) shr cx,1 shr cx,1 fix_4: cmp byte ptr [si-1],9 ; was last char output a tab? jne fix_5 ; if not, skip this next inc cx ; else add 1 TS inc si ; incr char pointer and dx,0FFF8h ; discard dx mod 8 remainder jmp short fix_4 ; continue while char = tab. fix_5: or cx,cx ; if cx=0 skip this next jz fix_6 add bx,cx ; add cx to bx tab count mov ax,cx ; put cx into ax shl ax,1 ; multiply by 8 shl ax,1 shl ax,1 add count,ax ; add ax to count mov al,9 ; put tab char in al rep stosb ; output cx tabs (adv di) fix_6: mov cx,dx ; put output pointer in cx and cx,7 ; cx mod 8 or cx,cx ; if it's 0, skip next jz fix_7 add bx,cx ; else add cx to bx counter add count,cx ; add cx to count (?) mov al,020h ; put BL in al rep stosb ; output cx BL's (adv di) fix_7: mov al,[si-1] ; put that last char back in al jmp bigloop ; and do it again. fix_done: mov cx,di ; put di pointer in cx sub cx,offset buffer + midbuf ; sub start of buffer ret fix_line endp ; SUBROUTINE ; sends line to std output put_line proc near jcxz put_ok push cx ; cx should have char count mov dx,offset buffer + midbuf mov bx,1 ; handle for std output mov ah,040h ; output cx chars. int 021h pop cx jc put_err ; cf=1 if error. sub cx,ax ; ax = cx if ok. jnz put_err put_ok: clc ret put_err: mov dx,offset errmsg3 stc ret put_line endp buffer db 0 ; buffer area: 1024 bytes allocated ; at pgm start (followed by 256 stack). codeseg ends end start