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;===========================================================================
; Copyright (c) 1990-1999 Info-ZIP. All rights reserved.
;
; See the accompanying file LICENSE, version 1999-Oct-05 or later
; (the contents of which are also included in zip.h) for terms of use.
; If, for some reason, both of these files are missing, the Info-ZIP license
; also may be found at: ftp://ftp.cdrom.com/pub/infozip/license.html
;===========================================================================
; match32.asm by Jean-loup Gailly.
; match32.asm, optimized version of longest_match() in deflate.c
; To be used only with 32 bit flat model. To simplify the code, the option
; -DDYN_ALLOC is not supported.
; This file is only optional. If you don't have an assembler, use the
; C version (add -DNO_ASM to CFLAGS in makefile and remove match.o
; from OBJI). If you have reduced WSIZE in zip.h, then make sure this is
; assembled with an equivalent -DWSIZE=<whatever>.
;
; Win32 (Windows NT) version - 1994/04/13 by Steve Salisbury
; * works with Microsoft MASM 6.1X and Microsoft Visual C++ / 32-bit edition
;
; The code in this file has been copied verbatim from match32.{asm|S};
; only the assembler syntax and metacommands have been adapted to
; the habits of the free LCC-Win32 C compiler package.
; IMPORTANT NOTE to the Info-ZIP editors:
; The TAB characters in this source file are required by the parser of
; the LCC-Win32 assembler program and MUST NOT be removed!!
;
;==============================================================================
;
; Do NOT assemble this source if external crc32 routine from zlib gets used.
;
;/* This version is for 386 Unix or OS/2 in 32 bit mode.
; * Warning: it uses the AT&T syntax: mov source,dest
; * This file is only optional. If you want to force the C version,
; * add -DNO_ASM to CFLAGS in Makefile and set OBJA to an empty string.
; * If you have reduced WSIZE in (g)zip.h, then make sure this is
; * assembled with an equivalent -DWSIZE=<whatever>.
; * This version assumes static allocation of the arrays (-DDYN_ALLOC not used).
; */
.text
.file "match.S"
.text
.type _match_init,function
_match_init:
ret
_$98:
.size _match_init,_$98-_match_init
.globl _match_init
;/*-----------------------------------------------------------------------
; * Set match_start to the longest match starting at the given string and
; * return its length. Matches shorter or equal to prev_length are discarded,
; * in which case the result is equal to prev_length and match_start is
; * garbage.
; * IN assertions: cur_match is the head of the hash chain for the current
; * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
; */
.align 4
.type _longest_match,function
_longest_match: ;/* int longest_match(cur_match) */
; cur_match equ 20(%esp)
; /* return address */ /* esp+16 */
push %ebp
push %edi
;/* esp+8 */
push %esi
;/* esp+4 */
push %ebx
;/* esp */
;/*
; * match equ esi
; * scan equ edi
; * chain_length equ ebp
; * best_len equ ebx
; * limit equ edx
; */
mov 20(%esp),%esi
mov _strstart,%edx
mov _max_chain_length,%ebp
mov %edx,%edi
sub $(32768-262),%edx
cld
jae limit_ok
sub %edx,%edx
limit_ok:
add $2+_window,%edi
mov _prev_length,%ebx
movw -2(%edi),%cx
movw -3(%ebx,%edi),%ax
cmp _good_match,%ebx
jb do_scan
shr $2,%ebp
jmp do_scan
.align 4
long_loop:
;/* at this point, edi == scan+2, esi == cur_match */
movw -3(%ebx,%edi),%ax
movw -2(%edi),%cx
short_loop:
;/*
; * at this point, di == scan+2, si == cur_match,
; * ax = scan[best_len-1..best_len] and cx = scan[0..1]
; */
and $(32768-1), %esi
dec %ebp
movw _prev(,%esi,2),%si
jz the_end
cmp %edx,%esi
jbe the_end
do_scan:
cmpw _window-1(%ebx,%esi),%ax
jne short_loop
cmpw _window(%esi),%cx
jne short_loop
add $2+_window,%esi
mov $((258>>1)-1),%ecx
mov %edi,%eax
repe; cmpsw
;/* loop until mismatch */
je maxmatch
;/* match of length MAX_MATCH? */
mismatch:
movb -2(%edi),%cl
xchg %edi,%eax
subb -2(%esi),%cl
sub %edi,%eax
sub $2+_window,%esi
sub %eax,%esi
subb $1,%cl
adc $0,%eax
cmp %ebx,%eax
jle long_loop
mov %esi,_match_start
mov %eax,%ebx
cmp _nice_match,%eax
; /* len >= nice_match ? */
jl long_loop
the_end:
mov %ebx,%eax
pop %ebx
pop %esi
pop %edi
pop %ebp
ret
.align 4
maxmatch:
cmpsb
jmp mismatch
_$99:
.size _longest_match,_$99-_longest_match
.globl _longest_match
.extern _nice_match
.extern _good_match
.extern _max_chain_length
.extern _match_start
.extern _strstart
.extern _prev_length
.extern _prev
.extern _window
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