Programmer 7500/MAX_PROGRAMMERS.iso/INFO/FREEMACS/EMAC16AS.ZIP/SEARCH.ASM

Assembly Source File | 1990-02-27 | 25.8 KB | 1,174 lines

;History:772,1
;Wed Nov 29 23:58:27 1989 Add support for \|
;Tue Nov 07 23:45:44 1989 match newlines in character classes.
;Mon Nov 06 00:40:16 1989 try to make backwards regexp searches work.
;Sat Nov 05 22:05:14 1988 let CR LF match LINENEW.
;10-08-88 08:48:54 add \n to regexp search.
;09-26-88 21:23:42 add case translation for character classes.
;08-19-88 23:36:40 closure didn't work because omatch iterated on matching.
;08-13-88 22:12:46 try forwards again.
;07-24-88 16:42:24 BOL and EOL match BOB and EOB respectively.
;07-21-88 22:49:18 add optimized search backwards.
;07-20-88 00:15:38 too late at night to continue...
;07-20-88 00:02:35 optimize forward searches.
;07-19-88 23:38:07 use the right omatch_chr for both regexps and literals.
;07-19-88 00:51:06 initialize the case table.
;07-18-88 21:20:18 don't increment di twice in omatch_NCCL
;07-18-88 00:04:34 replace bad patterns with "".
;07-17-88 23:15:23 Check for topbot right after incrementing di.
;07-17-88 22:55:12 search *at* the end_ptr (check for end_ptr after searching).
;07-17-88 18:54:53 when searching backwards, don't search past right_ptr.
;07-17-88 10:59:27 save di around omatch()
;07-17-88 10:42:13 omatch_CHR was incrementing di even if it didn't match.
;06-06-88 23:58:09 change the regexp chars to match Gnu's.
;07-06-87 06:55:31 Use botbot for eof, not LINENEW
    include    memory.def

data    segment    byte public

b_struc    struc
b    db    ?
b_struc    ends

w_struc    struc
w    dw    ?
w_struc    ends

    extrn    outpat: byte
    extrn    OUTPATSIZE: abs
inpat_ptr    dw    ?        ;beginning of input pattern.
direction    dw    ?        ;routine to increment di in correct direction.
scan_char    dw    ?        ;routine to scan for a character.
end_ptr        dw    ?        ;end of region we're searching.
right_ptr    dw    ?        ;rightmost end of region we're searching.
clo_si        dw    ?        ;saved pointer for closure.
last_ptr    dw    ?        ;pointer to last character matched.
which_chr    dw    ?        ;which omatch_CHR to use.
this_pattern    dw    ?        ;->this pattern (for closure).
last_pattern    dw    ?        ;->previous pattern (for closure).
last_or        dw    ?        ;->last or pointer.

    extrn    textseg: word

init_case        dw    init_case_table
case_ignore_table    db    256 dup(?)

data    ends


bufseg    segment    public

    extrn    toptop: word
    extrn    topbot: word
    extrn    bottop: word
    extrn    botbot: word

bufseg    ends


code    segment    byte public
    assume    cs:code, ds:data, ss:data

    public    slowly

    extrn    get_mark: near, set_mark_si: near
    extrn    get_syntax: near

    public    search
search:
;enter with ch=start mark, cl=end mark, dh=first mark, dl=last mark.
;start searching at mark ch.  If the string is found, then return the
;  beginning in mark dh, and the end in mark dl, and cy=0.  If the string
;  wasn't found, return cy=1.
    push    dx            ;save the first, last marks.
    push    es
    mov    es,textseg
    assume    es:bufseg
    push    ds            ;save ds
    push    es
    pop    ds
    assume    ds:bufseg        ;for get_mark
    mov    al,cl            ;get the end mark.
    push    cx
    call    get_mark
    mov    end_ptr,si        ;save a copy of the end.
    mov    right_ptr,si        ;save a copy of the end.
    pop    cx
    mov    al,ch            ;get the start mark.
    call    get_mark
    pop    ds            ;restore ds
    assume    ds:data
    mov    direction,offset inc_di
    cmp    si,end_ptr        ;start>=end?
    jb    search_4        ;no.  (doesn't matter if they're equal)
    mov    direction,offset dec_di    ;yes, go in reverse direction.
    mov    right_ptr,si        ;yes, remember that start is rightmost.
search_4:
    mov    di,si            ;get the pointer to our string.
    call    slowly
    pop    es
    assume    es:data
    pop    dx
    jc    search_1        ;not found.

    push    ds
    mov    ds,textseg        ;for set_mark_si
    assume    ds:bufseg
    mov    al,dh
    mov    si,di
    call    set_mark_si        ;set the first mark.

    mov    si,last_ptr
    mov    al,dl
    call    set_mark_si        ;set the last mark.

    pop    ds
    assume    ds:data
    clc                ;return a match.
    ret
search_1:
    stc                ;return no match.
    ret


    assume    ds:data, es:bufseg


scan_char_literal:
    or    sp,sp            ;ensure NZ in case cx=0.
    repne    scasb            ;search for the character.
    ret


scan_char_fold:
    xlat
    mov    ah,al
    or    sp,sp            ;if cx=0, be sure to return nz.
    jcxz    scan_char_fold_2
    shr    cx,1            ;we unrolled the loop once.
    jnc    scan_char_fold_1    ;if even, start at the top.
    inc    cx            ;otherwise, add one for the odd
    jmp    short scan_char_fold_3    ;  iteration, and jump to it.
scan_char_fold_1:
    mov    al,es:[di]        ;unroll this puppy once.
    add    di,dx
    xlat
    cmp    al,ah            ;compare them.
    je    scan_char_fold_2    ;if equal, we're done.
scan_char_fold_3:
    mov    al,es:[di]        ;now do the second set.
    add    di,dx
    xlat
    cmp    al,ah
    loopne    scan_char_fold_1
scan_char_fold_2:
    mov    al,ah            ;get our character back.
    ret


slowly:
;es:si -> first char to look at.
;es:right_ptr -> after last char to look at.
;return cy if no match,
;  else nc, si->start of match, last_ptr->after end of match.
    cmp    di,topbot        ;at topbot already?
    jne    slowly_0
    mov    di,bottop
slowly_0:
    mov    ax,which_chr        ;does the pattern start with a CHR?
    cmp    ax,word ptr outpat
    jne    slowly_1        ;no.
    cmp    outpat+2,CR        ;searching for literal CR?
    je    slowly_1        ;yes - don't optimize because of CRLFs.
    cmp    outpat+2,LF        ;searching for literal LF?
    je    slowly_1        ;yes - don't optimize because of CRLFs.

    mov    scan_char,offset scan_char_literal
    cmp    ax,offset omatch_CHR    ;Are we folding case?
    je    quickly_1        ;no.
    mov    scan_char,offset scan_char_fold
quickly_1:
    cmp    direction,offset inc_di    ;Are we going forwards?
    je    forwards_0        ;yes.
  if 0 ;disable optimization for now.
    jmp    slowly_1
  endif
    jmp    backwards_0        ;no.

slowly_1:
    mov    si,offset outpat    ;start at beginning of pattern.
    mov    bx,offset case_ignore_table
    push    di            ;remember where we're starting.
    call    omatch            ;now search.
    pop    di
    jnc    slowly_succeed        ;we found a match
;not found, should we give up?
    cmp    di,end_ptr        ;at the end yet?
    je    slowly_fail        ;yes - not found.
;not found, we have to bump di.
    call    direction
    jmp    slowly_1
slowly_fail:
    stc                ;not found.
    ret
slowly_succeed:
  if 1    ;an attempt to make backwards regexp searches work right.
    cmp    direction,offset inc_di    ;Are we going forwards?
    je    slowly_done        ;yes - we're done now.
slowly_backwards_again:
    call    dec_di            ;move backwards.
    push    last_ptr        ;remember the pointer to the end of it.
    mov    si,offset outpat    ;start at beginning of pattern.
    mov    bx,offset case_ignore_table
    push    di
    call    omatch            ;did it match?
    pop    di
    pop    ax
    jc    slowly_backwards_done    ;no - we're done.
    cmp    ax,last_ptr        ;did last_ptr change?
    je    slowly_backwards_again    ;no, we can try again.
slowly_backwards_done:
    mov    last_ptr,ax
    call    inc_di            ;point to the last match again.
slowly_done:
  endif
    clc
    ret

    public    forwards_0
forwards_0:
    mov    bx,offset case_ignore_table
    mov    al,outpat+2        ;get the character
    cmp    di,bottop        ;are we in the bottom?
    jae    forwards_2        ;yes - don't search the top.

    mov    cx,topbot        ;should we search to topbot
    cmp    cx,end_ptr        ;  or to end_ptr?
    jbe    forwards_3
    mov    cx,end_ptr        ;just to end_ptr.
forwards_3:
    sub    cx,di            ;compute the amount left in the top.
    mov    dx,1
    call    scan_char        ;scan for our character.
    je    forwards_1        ;we found it!

    cmp    di,end_ptr        ;are we at the end?
    jae    slowly_fail        ;yes - no match.

    mov    di,bottop
forwards_2:
    mov    cx,end_ptr        ;we only need search that far.
    sub    cx,di
    mov    dx,1
    call    scan_char        ;scan for our character.
    jne    slowly_fail        ;we didn't find it.
forwards_1:
    mov    si,offset outpat+3    ;start at beginning of pattern.
    push    di            ;remember where we're starting.
    call    omatch            ;now search.
    pop    di
    jnc    forwards_4        ;we matched - return it.
    cmp    di,end_ptr        ;are we at the end?
    jb    forwards_0        ;no - keep matching.
slowly_fail_j_1:
    jmp    slowly_fail        ;yes - no match.
forwards_4:
    dec    di            ;remember that we actually started
    jmp    slowly_succeed        ;  one character into the pattern.


    public    backwards_0
backwards_0:
    mov    bx,offset case_ignore_table
    mov    al,outpat+2        ;get the character
    cmp    di,bottop        ;are we in the top?
    jb    backwards_2        ;yes - don't search the bottom.
    je    backwards_5

    mov    si,bottop        ;should we search to bottop
    cmp    si,end_ptr        ;  or to end_ptr?
    jae    backwards_3
    mov    si,end_ptr        ;just to end_ptr.
backwards_3:

    dec    di
    mov    cx,di            ;compute the amount left in the bottom.
    sub    cx,si
    inc    cx            ;be sure to look at where di points.
    std
    mov    dx,-1
    call    scan_char        ;scan for our character.
    cld
    je    backwards_1        ;we found it!

backwards_5:
    cmp    di,end_ptr        ;are we at the end?
    jbe    slowly_fail_j_1        ;yes - no match.

    mov    di,topbot
    dec    di
backwards_2:
    mov    cx,di            ;we only search here if end_ptr is here.
    sub    cx,end_ptr
    inc    cx            ;be sure to compare where di is.
    std
    mov    dx,-1
    call    scan_char        ;scan for our character.
    cld
    jne    slowly_fail_j_1        ;we didn't find it.
backwards_1:
    mov    si,offset outpat+3    ;start at beginning of pattern.
    push    di            ;remember where we're starting.
    add    di,2            ;we post-decremented.
    call    omatch            ;now search.
    pop    di
    jnc    backwards_4        ;we suceeded.
    inc    di
    cmp    di,end_ptr        ;are we after the end?
    jb    slowly_fail_j_1        ;yes - no match.
    dec    di
    jmp    backwards_0
backwards_4:
    inc    di            ;remember that we post-decremented,
    jmp    slowly_succeed        ;  so we're one character too far.

inc_di:
;bump di forwards.
    inc    di
    cmp    di,topbot        ;at bottom of top?
    je    inc_di_1        ;yes - can't possibly be split over newline.
    cmp    es:[di-1].w,LINENEW    ;did we just move into a newline?
    jne    inc_di_2        ;no.
    inc    di            ;yes - skip LF part of newline.
    cmp    di,topbot        ;at topbot already?
    jne    inc_di_2
inc_di_1:
    mov    di,bottop
inc_di_2:
    ret

dec_di:
;bump di backwards.
    cmp    di,bottop        ;at top of bottom?
    jne    dec_di_1        ;no.
    mov    di,topbot        ;yes - load bottom of top.
dec_di_1:
    dec    di            ;back up to previous character.
    cmp    es:[di-1].w,LINENEW    ;at newline?
    jne    dec_di_2        ;no.
    cmp    di,bottop        ;at top of bottom now?
    je    dec_di_2        ;yes - can't possibly be split over newline.
    dec    di            ;yes - skip to beginning of newline.
dec_di_2:
    ret


omatch:
;return nc if we matched, cy if not.
;es:di -> source text
;ds:si -> pattern
omatch_0:
    cmp    di,topbot        ;at bottom of top?
    jne    omatch_1
    mov    di,bottop        ;yes, go to top of bottom.
omatch_1:
    lodsw
    call    ax
    jnc    omatch_0
    ret


;each of the omatch_XXX routines operates under the following constraints
;  on failure, return with cy set.
;  on matching (only used by omatch_EOS right now), return to caller's caller
;    with cy clear.
;  on success, bump si as needed so that it points to the next omatch,
;    bump di as needed (either zero or one), and return with cy clear.

    public    omatch_EOS
omatch_EOS:
    mov    last_ptr,di        ;remember the last thing we matched.
    add    sp,2            ;pop our return address.
    clc                ;if we get to the end of the
    ret                ;  pattern, then we matched.

    public    omatch_CLO
omatch_CLO:
    push    di            ;save the first closure pattern.
    mov    CLO_si,si        ;remember the pattern we're closing.
;Note that we don't have to worry about CLO_si being global because the
;  next pattern can't be another closure.
;match as many as fit the next pattern
    mov    bx,offset case_ignore_table
omatch_CLO_1:
    mov    si,CLO_si        ;get the pattern being closed.
    cmp    di,topbot        ;at bottom of top?
    jne    omatch_CLO_5
    mov    di,bottop        ;yes, go to top of bottom.
omatch_CLO_5:
    lodsw
    call    ax
    jnc    omatch_CLO_1
    pop    bx
;match only as many as fit the pattern after the next pattern.
omatch_CLO_2:
    push    si
    push    di
    push    bx
    mov    bx,offset case_ignore_table
    call    omatch            ;try to match rest of pattern.
    pop    bx
    pop    di
    pop    si
    jnc    omatch_CLO_4        ;go if it matched.
    cmp    di,bottop        ;backing up past the point?
    jne    omatch_CLO_3        ;no - just decrement.
    mov    di,topbot        ;yes - get the bottom of the top.
omatch_CLO_3:
    dec    di            ;point to the previous character.
    cmp    di,bx            ;zero or more matches still?
    jae    omatch_CLO_2        ;yes.
    stc                ;no matches--return no match.
    ret
omatch_CLO_4:
    pop    bx            ;get rid of our return address.
    ret


omatch_OR:
    add    si,2            ;skip past our param.
    push    si
    push    di
    mov    bx,offset case_ignore_table
    call    omatch            ;try to match rest of pattern.
    jnc    omatch_OR_1        ;go if it matched.
    pop    di
    pop    si
    push    si
    mov    si,[si-2]        ;point to the next or-clause.
    push    di
    call    omatch
    jnc    omatch_OR_1        ;go if it matched.
    pop    di
    pop    si
;guaranteed cy.
    ret
omatch_OR_1:
    add    sp,6            ;get rid of si,di, and our return addr.
;guaranteed nc.
    ret


    public    omatch_CHR
omatch_CHR:
    cmp    di,right_ptr        ;are we at the end?
    je    omatch_CHR_skip        ;yes - we never match CHR
    cmp    es:[di].w,LINENEW
    je    omatch_CHR_linenew
    cmpsb
    je    omatch_yes        ;if they're the same, match again.
    dec    di            ;don't modify buffer pointer if no match.
    stc
    ret
omatch_CHR_linenew:
    cmp    [si].b,CR        ;got a LINENEW, are we looking for one?
    jne    omatch_CHR_skip        ;no.
    mov    ax,which_chr        ;is the next one another char?
    cmp    [si+1].w,ax
    jne    omatch_CHR_skip        ;no - no match.
    cmp    [si+1+2].b,LF        ;Are we really looking for a linenew?
    jne    omatch_CHR_skip        ;no - no match.
    add    si,1+2+1        ;skip past the two of them.
    add    di,2            ;skip in the buffer also.
    clc
    ret
omatch_CHR_skip:
    inc    si            ;skip the pattern character.
omatch_CHR_no:
    stc
    ret
omatch_yes:
    clc
    ret


    public    omatch_NCHR
omatch_NCHR:
    cmp    di,right_ptr        ;are we at the end?
    je    omatch_CHR_skip        ;yes - we never match CHR
    cmp    es:[di].w,LINENEW
    je    omatch_CHR_linenew
    lodsb
    xlat
    mov    ah,al
    mov    al,es:[di]
    inc    di
    xlat
    cmp    ah,al
    je    omatch_yes        ;if they're the same, match again.
    dec    di            ;don't modify buffer pointer if no match.
    stc
    ret


omatch_NL:
    cmp    di,right_ptr        ;are we at the end?
    je    omatch_NL_no        ;yes - we never match newline.
    cmp    es:[di].w,LINENEW    ;is it newline?
    jne    omatch_NL_no        ;no - don't match it.
    add    di,2            ;yes - skip it.
    clc
    ret
omatch_NL_no:
    stc
    ret


    public    omatch_BOB
omatch_BOB:
;match beginning of buffer.
    cmp    di,toptop        ;are we at the beginning of the buffer?
    je    omatch_yes        ;yes.
    stc
    ret


    public    omatch_BOL
omatch_BOL:
;match beginning of line.
    push    di            ;we might have to look at the top.
    cmp    di,bottop        ;are we at the point?
    jne    omatch_BOL_1        ;yes - ok.
    mov    di,topbot        ;no - get the top.
omatch_BOL_1:
    cmp    di,toptop
    je    omatch_BOL_2
    cmp    es:[di-2].w,LINENEW
    pop    di
    jne    omatch_CHR_no
    clc
    ret
omatch_BOL_2:
    pop    di
    clc
    ret


    public    omatch_ISW
omatch_ISW:
;match word character.
    cmp    di,botbot
    je    omatch_CHR_no
    cmp    es:[di].w,LINENEW
    je    omatch_CHR_no
    call    chars_around_di
    test    al,1            ;word character?
    je    omatch_CHR_no        ;nope--no match.
    inc    di            ;match the character.
    clc
    ret


    public    omatch_NOW
omatch_NOW:
;match word character.
    cmp    di,botbot
    je    omatch_no
    cmp    es:[di].w,LINENEW
    je    omatch_no
    call    chars_around_di
    test    al,1            ;whitespace before and word after?
    jne    omatch_no        ;nope--no match.
    inc    di            ;match the character.
    clc
    ret


    public    omatch_BOW
omatch_BOW:
;match beginning of word.
    cmp    di,botbot
    je    omatch_no
    cmp    es:[di].w,LINENEW
    je    omatch_no
    call    chars_around_di
    cmp    al,1            ;whitespace before and word after?
    jne    omatch_no        ;nope--no match.
    clc
    ret


    public    omatch_EOW
omatch_EOW:
;match end of word.
    call    chars_around_di
    cmp    al,2            ;word before and whitespace after?
    jne    omatch_no        ;nope--no match.
    clc
    ret


    public    omatch_WOR
omatch_WOR:
;match end of word.
    call    chars_around_di
    cmp    al,2            ;word before and whitespace after?
    je    omatch_WOR_yes        ;yes - match.
    cmp    al,1            ;whitespace before and word after?
    je    omatch_WOR_yes        ;yes - match.
    stc
    ret
omatch_WOR_yes:
    clc
    ret


    public    omatch_NWR
omatch_NWR:
;match end of word.
    call    chars_around_di
    cmp    al,0            ;whitespace before and whitespace after?
    je    omatch_NWR_yes        ;yes - match.
    cmp    al,3            ;word before and word after?
    je    omatch_NWR_yes        ;yes - match.
    stc
    ret
omatch_NWR_yes:
    clc
    ret


    public    omatch_EOB
omatch_EOB:
;match end of buffer.
    cmp    di,botbot        ;are we at the end of the buffer?
    je    omatch_NWR_yes        ;yes.
    stc
    ret


    public    omatch_EOL
omatch_EOL:
;match end of line.
    cmp    di,botbot        ;are we at the end?
    je    omatch_EOL_yes        ;yes.
    cmp    es:[di].w,LINENEW
    jne    omatch_no
omatch_EOL_yes:
    clc
    ret
omatch_no:
    stc
    ret


    public    omatch_ANY
omatch_ANY:
;match any single character.
    cmp    di,right_ptr        ;are we at the end?
    je    omatch_no        ;yes - we never match ANY
    cmp    es:[di].w,LINENEW    ;we never match EOL.
    je    omatch_no
    inc    di
    clc
    ret


    public    omatch_CCL
omatch_CCL:
;match a character class.
    cmp    di,right_ptr        ;are we at the end?
    je    omatch_ccl_no        ;yes - we never match CCL
    cmp    es:[di].w,LINENEW    ;we never match EOL.
    je    omatch_ccl_newline
    call    locate            ;see if it's in our set.
    jnz    omatch_no        ;nope.
    inc    di
    clc
    ret
omatch_ccl_newline:
    lea    ax,[di+1]        ;are we near the end?
    cmp    ax,right_ptr
    je    omatch_ccl_no        ;yes - no match.
    cmp    ds:[si+1].w,LINENEW    ;does the class begin with crlf?
    jne    omatch_ccl_no        ;no - don't match it.
    lodsb                ;skip past this pattern.
    xor    ah,ah
    add    si,ax
    add    di,2
    clc
    ret


    public    omatch_NCCL
omatch_NCCL:
;match not in a character class.
    cmp    di,right_ptr        ;are we at the end?
    je    omatch_ccl_no        ;yes - we never match NCCL
    cmp    es:[di].w,LINENEW    ;we only match EOL if it begins the class.
    je    omatch_ccl_no
    call    locate            ;see if it's in our set.
    jz    omatch_ccl_no        ;yes - we don't match.
    inc    di
    clc
    ret
omatch_ccl_no:
    lodsb                ;skip past the pattern.
    xor    ah,ah
    add    si,ax
    stc
    ret


locate:
;es:di -> search string, bx -> case translate table.
;ds:si -> CCL
;exit with zr if found, nz if not found, si -> after the pattern.
    push    cx
    lodsb                ;get the count.
    mov    cl,al
    xor    ch,ch
    mov    al,es:[di]        ;get the character we're trying to match.
    xlat                ;case translate it.
    mov    ah,al            ;keep it somewhere safe.
locate_2:
    lodsb
    xlat
    cmp    al,ah            ;is this one it?
    loopne    locate_2
    lahf                ;remember whether or not we found it.
    add    si,cx
    sahf
    pop    cx
    ret


chars_around_di:
;return al bit 1=syntax of char to left of point.
;    al bit 0=syntax of char to right of point.
    push    di            ;get the character before point.
    cmp    di,bottop        ;are we at the point?
    jne    chars_around_di_1    ;yes.
    mov    di,topbot
chars_around_di_1:
    xor    al,al            ;if no character, it's whitespace.
    cmp    di,toptop
    je    chars_around_di_2
    mov    al,es:[di-1]
    call    get_syntax        ;get the syntax for the char before point.
    and    al,1            ;isolate the 'word' bit.
chars_around_di_2:
    shl    al,1
    mov    ah,al
    pop    di

    xor    al,al            ;if no character, it's whitespace.
    cmp    di,botbot        ;are we at the end?
    je    chars_around_di_3    ;yes - can't match beginning of word.
    mov    al,es:[di]
    call    get_syntax
    and    al,1
chars_around_di_3:
    or    al,ah            ;include the syntax of the char to left of point.
    ret


    assume    ds:data

    public    set_pattern
set_pattern:
;enter with si, cx->pattern.  dx<>0 if regular expression.  di <> 0 if we
;  want to fold case.
;exit with cy=1 if error.
    call    init_case
    mov    ax,offset omatch_CHR
    or    di,di
    je    set_pattern_0
    mov    ax,offset omatch_NCHR
set_pattern_0:
    mov    which_chr,ax        ;remember which omatch_CHR to use.
    or    dx,dx
    jne    regexp_pat
    mov    di,offset outpat
    jcxz    set_pattern_1
    mov    bp,offset outpat-2
    add    bp,OUTPATSIZE
set_pattern_2:
    cmp    di,bp            ;do we have enough room?
    jae    set_pattern_3        ;no - quit now.
    stosw                ;store the appropriate comparison omatcher.
    movsb
    loop    set_pattern_2
set_pattern_1:
    mov    ax,offset omatch_EOS    ;store the end of string.
    stosw
    clc
    ret
set_pattern_3:
    stc
    ret


    public    regexp_pat
regexp_pat:
;enter with si, cx->pattern.
;exit with cy=1 if error.
    mov    bx,cx
    mov    [si+bx],byte ptr 0    ;store the terminating null.
    call    makepat
    jnc    regexp_pat_1
    mov    word ptr outpat,offset omatch_EOS    ;uh-oh, bad pattern -- null it.
regexp_pat_1:
    ret


makepat:
;si -> source pat (null terminated)
;di -> dest pattern, dx -> last dest entry.
;bx -> last closure
;return cy=1 if error.
    mov    inpat_ptr,si
    mov    di,offset outpat
    mov    dx,OUTPATSIZE
    add    dx,di
    mov    last_pattern,-1        ;remember where the previous pattern started.
    mov    last_or,di        ;remember that it's here.
makepat_1:
    lodsb                ;get the first character.
    or    al,al            ;end of string?
    je    makepat_0        ;yes.

    mov    this_pattern,di        ;remember where this pattern starts.

    cmp    al,'\'            ;are we escaping something?
    jne    makepat_a
    cmp    byte ptr [si],0        ;is the '\' at the end?
    je    makepat_9        ;yes - just use \.
    lodsb                ;get the escaped char.
    call    escaped_char        ;check for the special escapes.
    jmp    makepat_2
makepat_a:
    cmp    al,'.'
    jne    makepat_3
    mov    ax,offset omatch_ANY
    call    addset
    jmp    makepat_2
;this really belongs at the end of makepat, but the short jump can't get there.
makepat_0:
    mov    ax,offset omatch_EOS
    call    addset
    cmp    di,dx
    jne    makepat__0_1
    stc
    ret
makepat__0_1:
    clc
    ret
makepat_3:
    cmp    al,'^'
    jne    makepat_7
    lea    ax,[si-1]        ;get the buffer pointer.
    cmp    ax,inpat_ptr        ;are we at the beginning?
    jne    makepat_6        ;no - this can't be it.
    mov    ax,offset omatch_BOL
    call    addset
    jmp    makepat_2
makepat_6:
    mov    al,'^'
    call    addchar
    jmp    makepat_2
makepat_7:
    cmp    al,'$'
    jne    makepat_8
    cmp    word ptr [si],'\' + '|'*256;is the '$' at the end of an alternation?
    je    makepat_7a        ;no - not special.
    cmp    byte ptr [si],0        ;is the '$' at the end?
    jne    makepat_9        ;no - not special.
makepat_7a:
    mov    ax,offset omatch_EOL
    call    addset
    jmp    makepat_2
makepat_9:
    call    addchar
    jmp    makepat_2
makepat_8:
    cmp    al,'['
    jne    makepat_10
    call    getccl
    jnc    makepat_2
    pop    di
    stc
    ret
makepat_10:
    cmp    al,'*'
    jne    makepat_11
    cmp    last_pattern,0        ;is last_pattern>0?
    jnge    makepat_12        ;no - not closure.
    mov    bx,last_pattern
    mov    ax,word ptr [bx]
    cmp    ax,offset omatch_CLO    ;trying to close a closure?
    je    makepat_12        ;yes - not closure.
    cmp    ax,offset omatch_BOL    ;trying to close a beginning of line?
    je    makepat_12        ;yes - not closure.
    call    stclos
    mov    this_pattern,bx        ;remember where this one was.
    jmp    makepat_2
makepat_11:
;put more characters here.
makepat_12:
    call    addchar
    jmp    makepat_2
makepat_2:
    mov    bx,this_pattern
    mov    last_pattern,bx
    jmp    makepat_1


escaped_char:
    mov    cx,offset omatch_NL
    cmp    al,"n"            ;newline?
    je    escaped_1

    mov    cx,offset omatch_BOB
    cmp    al,"`"            ;beginning of buffer?
    je    escaped_1

    mov    cx,offset omatch_EOB
    cmp    al,"'"            ;end of buffer?
    je    escaped_1

    mov    cx,offset omatch_WOR
    cmp    al,"b"            ;beginning or end of word?
    je    escaped_1

    mov    cx,offset omatch_NWR
    cmp    al,"B"            ;not beginning nor end of word?
    je    escaped_1

    mov    cx,offset omatch_BOW
    cmp    al,"<"            ;beginning of word?
    je    escaped_1

    mov    cx,offset omatch_EOW
    cmp    al,">"            ;end of word?
    je    escaped_1

    mov    cx,offset omatch_ISW
    cmp    al,"w"            ;word character?
    je    escaped_1

    mov    cx,offset omatch_NOW
    cmp    al,"W"            ;not word character?
    je    escaped_1

    cmp    al,'|'            ;is this an "or" operator?
    jne    addchar            ;no.

    mov    inpat_ptr,si        ;start a new regexp here...
    call    stor            ;store a "or" operator.
    ret
escaped_1:
    mov    ax,cx
    call    addset
    ret

addchar:
;al = CHR to put.
    push    ax
    mov    ax,which_chr        ;use the right omatch_chr.
    call    addset
    pop    ax
    call    addbyte
    ret


addset:            ;only command chars call addset.
    call    addbyte
    xchg    ah,al
    call    addbyte
    xchg    ah,al
    ret


addbyte:
;al = char to put, di->dest, dx->end of dest.
    cmp    di,dx
    je    addbyte_1
    mov    [di],al
    inc    di
addbyte_1:
    ret


stclos:
;di->last set added + 1
;bx->last closure added
    push    di
stclos_1:
    dec    di
    mov    al,[di]
    mov    [di+2],al
    cmp    di,bx
    jne    stclos_1
stclos_2:
    mov    word ptr [bx],offset omatch_CLO
    pop    di
    add    di,2
    ret


stor:
;di->last set added + 1
    mov    bx,last_or
    push    di
stor_1:
    dec    di
    mov    al,[di]
    mov    [di+4],al
    cmp    di,bx
    jne    stor_1
stor_2:
    pop    di            ;get the new last set.
    add    di,4
    mov    ax,offset omatch_EOS    ;store the end of string.
    stosw
    mov    word ptr [bx],offset omatch_OR
    mov    [bx+2],di        ;remember where the next starts.
    mov    last_or,bx
    ret


getccl:
;si -> source (null terminated)
;di -> dest, dx -> end of dest
;return cy=1 if error.
    lodsb
    cmp    al,'^'
    jne    getccl_1
    mov    ax,offset omatch_NCCL
    call    addset
    jmp    getccl_2
getccl_1:
    dec    si            ;unparse the '^'.
    mov    ax,offset omatch_CCL
    call    addset
getccl_2:
    push    bx
    mov    bx,di
    call    addbyte            ;leave room for count
    call    dodash
    mov    ax,di
    sub    ax,bx
    dec    al
    mov    [bx],al
    pop    bx
    lodsb
    cmp    al,']'            ;now make sure that we end in ']'.
    je    getccl_3        ;yup, we do.
    dec    si            ;make si -> the null.
    stc
    ret
getccl_3:
    clc
    ret


dodash:
;si -> source pattern (null terminated)
;di -> destination pattern
;dx -> end of destination pattern
    push    bx
    mov    bx,si
dodash_1:
    lodsb
    or    al,al
    je    dodash_2
    cmp    al,']'
    je    dodash_2
    cmp    al,'-'
    je    dodash_4
    call    addbyte
    jmp    dodash_1
dodash_4:
    cmp    si,bx            ;'-' at beginning?
    je    dodash_5
    cmp    [si].b,0        ;or '-' at end?
    jne    dodash_6
dodash_5:
    mov    al,'-'            ;if at beginning or at end, just a '-'
    call    addbyte
    jmp    dodash_1
dodash_6:
    mov    al,[si-2]        ;in increasing alphabetic order?
    cmp    al,[si]
    ja    dodash_5        ;no - forget it.
    call    alphanumeric        ;left char alphanumeric?
    jnc    dodash_5        ;no - forget it.
    mov    al,[si]
    call    alphanumeric        ;right char alphanumeric?
    jnc    dodash_5        ;no - forget it.
    mov    al,[si-2]
dodash_7:
    inc    al            ;pre-increment -- the first one's there.
    cmp    al,[si]
    ja    dodash_9
    call    addbyte
    jmp    dodash_7
dodash_9:
    inc    si
    jmp    dodash_1
dodash_2:
    dec    si
    pop    bx
    ret


alphanumeric:
;return cy=1 if al is alphanumeric
    cmp    al,'0'
    jb    alphanumeric_1
    cmp    al,'9'
    jbe    alphanumeric_2
    cmp    al,'A'
    jb    alphanumeric_1
    cmp    al,'Z'
    jbe    alphanumeric_2
    cmp    al,'a'
    jb    alphanumeric_1
    cmp    al,'z'
    jbe    alphanumeric_2
alphanumeric_1:
    clc
    ret
alphanumeric_2:
    stc
    ret


init_case_table:
    push    bx
    mov    init_case,offset init_case_2
    mov    bx,0
init_case_0:
    mov    case_ignore_table[bx],bl
    inc    bl
    jne    init_case_0
;now translate 'a' to 'A'.
    mov    bx,'a'
init_case_1:
    mov    al,bl
    sub    al,20h
    mov    case_ignore_table[bx],al
    inc    bx
    cmp    bx,'z'
    jbe    init_case_1
    pop    bx
init_case_2:
    ret


code    ends

    end