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; gvmat32.asm -- Asm portion of the optimized longest_match for 32 bits x86
; Copyright (C) 1995-1996 Jean-loup Gailly and Gilles Vollant.
; File written by Gilles Vollant, by modifiying the longest_match
; from Jean-loup Gailly in deflate.c
;
; http://www.zlib.net
; http://www.winimage.com/zLibDll
; http://www.muppetlabs.com/~breadbox/software/assembly.html
;
; For Visual C++ 4.x and higher and ML 6.x and higher
; ml.exe is in directory \MASM611C of Win95 DDK
; ml.exe is also distributed in http://www.masm32.com/masmdl.htm
; and in VC++2003 toolkit at http://msdn.microsoft.com/visualc/vctoolkit2003/
;
; this file contain two implementation of longest_match
;
; longest_match_7fff : written 1996 by Gilles Vollant optimized for
; first Pentium. Assume s->w_mask == 0x7fff
; longest_match_686 : written by Brian raiter (1998), optimized for Pentium Pro
;
; for using an seembly version of longest_match, you need define ASMV in project
; There is two way in using gvmat32.asm
;
; A) Suggested method
; if you want include both longest_match_7fff and longest_match_686
; compile the asm file running
; ml /coff /Zi /Flgvmat32.lst /c gvmat32.asm
; and include gvmat32c.c in your project
; if you have an old cpu (386,486 or first Pentium) and s->w_mask==0x7fff,
; longest_match_7fff will be used
; if you have a more modern CPU (Pentium Pro, II and higher)
; longest_match_686 will be used
; on old cpu with s->w_mask!=0x7fff, longest_match_686 will be used,
; but this is not a sitation you'll find often
;
; B) Alternative
; if you are not interresed in old cpu performance and want the smaller
; binaries possible
;
; compile the asm file running
; ml /coff /Zi /c /Flgvmat32.lst /DNOOLDPENTIUMCODE gvmat32.asm
; and do not include gvmat32c.c in your project (ou define also
; NOOLDPENTIUMCODE)
;
; note : as I known, longest_match_686 is very faster than longest_match_7fff
; on pentium Pro/II/III, faster (but less) in P4, but it seem
; longest_match_7fff can be faster (very very litte) on AMD Athlon64/K8
;
; see below : zlib1222add must be adjuster if you use a zlib version < 1.2.2.2
;uInt longest_match_7fff(s, cur_match)
; deflate_state *s;
; IPos cur_match; /* current match */
NbStack equ 76
cur_match equ dword ptr[esp+NbStack-0]
str_s equ dword ptr[esp+NbStack-4]
; 5 dword on top (ret,ebp,esi,edi,ebx)
adrret equ dword ptr[esp+NbStack-8]
pushebp equ dword ptr[esp+NbStack-12]
pushedi equ dword ptr[esp+NbStack-16]
pushesi equ dword ptr[esp+NbStack-20]
pushebx equ dword ptr[esp+NbStack-24]
chain_length equ dword ptr [esp+NbStack-28]
limit equ dword ptr [esp+NbStack-32]
best_len equ dword ptr [esp+NbStack-36]
window equ dword ptr [esp+NbStack-40]
prev equ dword ptr [esp+NbStack-44]
scan_start equ word ptr [esp+NbStack-48]
wmask equ dword ptr [esp+NbStack-52]
match_start_ptr equ dword ptr [esp+NbStack-56]
nice_match equ dword ptr [esp+NbStack-60]
scan equ dword ptr [esp+NbStack-64]
windowlen equ dword ptr [esp+NbStack-68]
match_start equ dword ptr [esp+NbStack-72]
strend equ dword ptr [esp+NbStack-76]
NbStackAdd equ (NbStack-24)
.386p
name gvmatch
.MODEL FLAT
; all the +zlib1222add offsets are due to the addition of fields
; in zlib in the deflate_state structure since the asm code was first written
; (if you compile with zlib 1.0.4 or older, use "zlib1222add equ (-4)").
; (if you compile with zlib between 1.0.5 and 1.2.2.1, use "zlib1222add equ 0").
; if you compile with zlib 1.2.2.2 or later , use "zlib1222add equ 8").
zlib1222add equ 8
; Note : these value are good with a 8 bytes boundary pack structure
dep_chain_length equ 74h+zlib1222add
dep_window equ 30h+zlib1222add
dep_strstart equ 64h+zlib1222add
dep_prev_length equ 70h+zlib1222add
dep_nice_match equ 88h+zlib1222add
dep_w_size equ 24h+zlib1222add
dep_prev equ 38h+zlib1222add
dep_w_mask equ 2ch+zlib1222add
dep_good_match equ 84h+zlib1222add
dep_match_start equ 68h+zlib1222add
dep_lookahead equ 6ch+zlib1222add
_TEXT segment
IFDEF NOUNDERLINE
IFDEF NOOLDPENTIUMCODE
public longest_match
public match_init
ELSE
public longest_match_7fff
public cpudetect32
public longest_match_686
ENDIF
ELSE
IFDEF NOOLDPENTIUMCODE
public _longest_match
public _match_init
ELSE
public _longest_match_7fff
public _cpudetect32
public _longest_match_686
ENDIF
ENDIF
MAX_MATCH equ 258
MIN_MATCH equ 3
MIN_LOOKAHEAD equ (MAX_MATCH+MIN_MATCH+1)
IFNDEF NOOLDPENTIUMCODE
IFDEF NOUNDERLINE
longest_match_7fff proc near
ELSE
_longest_match_7fff proc near
ENDIF
mov edx,[esp+4]
push ebp
push edi
push esi
push ebx
sub esp,NbStackAdd
; initialize or check the variables used in match.asm.
mov ebp,edx
; chain_length = s->max_chain_length
; if (prev_length>=good_match) chain_length >>= 2
mov edx,[ebp+dep_chain_length]
mov ebx,[ebp+dep_prev_length]
cmp [ebp+dep_good_match],ebx
ja noshr
shr edx,2
noshr:
; we increment chain_length because in the asm, the --chain_lenght is in the beginning of the loop
inc edx
mov edi,[ebp+dep_nice_match]
mov chain_length,edx
mov eax,[ebp+dep_lookahead]
cmp eax,edi
; if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
jae nolookaheadnicematch
mov edi,eax
nolookaheadnicematch:
; best_len = s->prev_length
mov best_len,ebx
; window = s->window
mov esi,[ebp+dep_window]
mov ecx,[ebp+dep_strstart]
mov window,esi
mov nice_match,edi
; scan = window + strstart
add esi,ecx
mov scan,esi
; dx = *window
mov dx,word ptr [esi]
; bx = *(window+best_len-1)
mov bx,word ptr [esi+ebx-1]
add esi,MAX_MATCH-1
; scan_start = *scan
mov scan_start,dx
; strend = scan + MAX_MATCH-1
mov strend,esi
; bx = scan_end = *(window+best_len-1)
; IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
; s->strstart - (IPos)MAX_DIST(s) : NIL;
mov esi,[ebp+dep_w_size]
sub esi,MIN_LOOKAHEAD
; here esi = MAX_DIST(s)
sub ecx,esi
ja nodist
xor ecx,ecx
nodist:
mov limit,ecx
; prev = s->prev
mov edx,[ebp+dep_prev]
mov prev,edx
;
mov edx,dword ptr [ebp+dep_match_start]
mov bp,scan_start
mov eax,cur_match
mov match_start,edx
mov edx,window
mov edi,edx
add edi,best_len
mov esi,prev
dec edi
; windowlen = window + best_len -1
mov windowlen,edi
jmp beginloop2
align 4
; here, in the loop
; eax = ax = cur_match
; ecx = limit
; bx = scan_end
; bp = scan_start
; edi = windowlen (window + best_len -1)
; esi = prev
;// here; chain_length <=16
normalbeg0add16:
add chain_length,16
jz exitloop
normalbeg0:
cmp word ptr[edi+eax],bx
je normalbeg2noroll
rcontlabnoroll:
; cur_match = prev[cur_match & wmask]
and eax,7fffh
mov ax,word ptr[esi+eax*2]
; if cur_match > limit, go to exitloop
cmp ecx,eax
jnb exitloop
; if --chain_length != 0, go to exitloop
dec chain_length
jnz normalbeg0
jmp exitloop
normalbeg2noroll:
; if (scan_start==*(cur_match+window)) goto normalbeg2
cmp bp,word ptr[edx+eax]
jne rcontlabnoroll
jmp normalbeg2
contloop3:
mov edi,windowlen
; cur_match = prev[cur_match & wmask]
and eax,7fffh
mov ax,word ptr[esi+eax*2]
; if cur_match > limit, go to exitloop
cmp ecx,eax
jnbexitloopshort1:
jnb exitloop
; if --chain_length != 0, go to exitloop
; begin the main loop
beginloop2:
sub chain_length,16+1
; if chain_length <=16, don't use the unrolled loop
jna normalbeg0add16
do16:
cmp word ptr[edi+eax],bx
je normalbeg2dc0
maccn MACRO lab
and eax,7fffh
mov ax,word ptr[esi+eax*2]
cmp ecx,eax
jnb exitloop
cmp word ptr[edi+eax],bx
je lab
ENDM
rcontloop0:
maccn normalbeg2dc1
rcontloop1:
maccn normalbeg2dc2
rcontloop2:
maccn normalbeg2dc3
rcontloop3:
maccn normalbeg2dc4
rcontloop4:
maccn normalbeg2dc5
rcontloop5:
maccn normalbeg2dc6
rcontloop6:
maccn normalbeg2dc7
rcontloop7:
maccn normalbeg2dc8
rcontloop8:
maccn normalbeg2dc9
rcontloop9:
maccn normalbeg2dc10
rcontloop10:
maccn short normalbeg2dc11
rcontloop11:
maccn short normalbeg2dc12
rcontloop12:
maccn short normalbeg2dc13
rcontloop13:
maccn short normalbeg2dc14
rcontloop14:
maccn short normalbeg2dc15
rcontloop15:
and eax,7fffh
mov ax,word ptr[esi+eax*2]
cmp ecx,eax
jnb exitloop
sub chain_length,16
ja do16
jmp normalbeg0add16
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
normbeg MACRO rcontlab,valsub
; if we are here, we know that *(match+best_len-1) == scan_end
cmp bp,word ptr[edx+eax]
; if (match != scan_start) goto rcontlab
jne rcontlab
; calculate the good chain_length, and we'll compare scan and match string
add chain_length,16-valsub
jmp iseq
ENDM
normalbeg2dc11:
normbeg rcontloop11,11
normalbeg2dc12:
normbeg short rcontloop12,12
normalbeg2dc13:
normbeg short rcontloop13,13
normalbeg2dc14:
normbeg short rcontloop14,14
normalbeg2dc15:
normbeg short rcontloop15,15
normalbeg2dc10:
normbeg rcontloop10,10
normalbeg2dc9:
normbeg rcontloop9,9
normalbeg2dc8:
normbeg rcontloop8,8
normalbeg2dc7:
normbeg rcontloop7,7
normalbeg2dc6:
normbeg rcontloop6,6
normalbeg2dc5:
normbeg rcontloop5,5
normalbeg2dc4:
normbeg rcontloop4,4
normalbeg2dc3:
normbeg rcontloop3,3
normalbeg2dc2:
normbeg rcontloop2,2
normalbeg2dc1:
normbeg rcontloop1,1
normalbeg2dc0:
normbeg rcontloop0,0
; we go in normalbeg2 because *(ushf*)(match+best_len-1) == scan_end
normalbeg2:
mov edi,window
cmp bp,word ptr[edi+eax]
jne contloop3 ; if *(ushf*)match != scan_start, continue
iseq:
; if we are here, we know that *(match+best_len-1) == scan_end
; and (match == scan_start)
mov edi,edx
mov esi,scan ; esi = scan
add edi,eax ; edi = window + cur_match = match
mov edx,[esi+3] ; compare manually dword at match+3
xor edx,[edi+3] ; and scan +3
jz begincompare ; if equal, go to long compare
; we will determine the unmatch byte and calculate len (in esi)
or dl,dl
je eq1rr
mov esi,3
jmp trfinval
eq1rr:
or dx,dx
je eq1
mov esi,4
jmp trfinval
eq1:
and edx,0ffffffh
jz eq11
mov esi,5
jmp trfinval
eq11:
mov esi,6
jmp trfinval
begincompare:
; here we now scan and match begin same
add edi,6
add esi,6
mov ecx,(MAX_MATCH-(2+4))/4 ; scan for at most MAX_MATCH bytes
repe cmpsd ; loop until mismatch
je trfin ; go to trfin if not unmatch
; we determine the unmatch byte
sub esi,4
mov edx,[edi-4]
xor edx,[esi]
or dl,dl
jnz trfin
inc esi
or dx,dx
jnz trfin
inc esi
and edx,0ffffffh
jnz trfin
inc esi
trfin:
sub esi,scan ; esi = len
trfinval:
; here we have finised compare, and esi contain len of equal string
cmp esi,best_len ; if len > best_len, go newbestlen
ja short newbestlen
; now we restore edx, ecx and esi, for the big loop
mov esi,prev
mov ecx,limit
mov edx,window
jmp contloop3
newbestlen:
mov best_len,esi ; len become best_len
mov match_start,eax ; save new position as match_start
cmp esi,nice_match ; if best_len >= nice_match, exit
jae exitloop
mov ecx,scan
mov edx,window ; restore edx=window
add ecx,esi
add esi,edx
dec esi
mov windowlen,esi ; windowlen = window + best_len-1
mov bx,[ecx-1] ; bx = *(scan+best_len-1) = scan_end
; now we restore ecx and esi, for the big loop :
mov esi,prev
mov ecx,limit
jmp contloop3
exitloop:
; exit : s->match_start=match_start
mov ebx,match_start
mov ebp,str_s
mov ecx,best_len
mov dword ptr [ebp+dep_match_start],ebx
mov eax,dword ptr [ebp+dep_lookahead]
cmp ecx,eax
ja minexlo
mov eax,ecx
minexlo:
; return min(best_len,s->lookahead)
; restore stack and register ebx,esi,edi,ebp
add esp,NbStackAdd
pop ebx
pop esi
pop edi
pop ebp
ret
InfoAuthor:
; please don't remove this string !
; Your are free use gvmat32 in any fre or commercial apps if you don't remove the string in the binary!
db 0dh,0ah,"GVMat32 optimised assembly code written 1996-98 by Gilles Vollant",0dh,0ah
IFDEF NOUNDERLINE
longest_match_7fff endp
ELSE
_longest_match_7fff endp
ENDIF
IFDEF NOUNDERLINE
cpudetect32 proc near
ELSE
_cpudetect32 proc near
ENDIF
push ebx
pushfd ; push original EFLAGS
pop eax ; get original EFLAGS
mov ecx, eax ; save original EFLAGS
xor eax, 40000h ; flip AC bit in EFLAGS
push eax ; save new EFLAGS value on stack
popfd ; replace current EFLAGS value
pushfd ; get new EFLAGS
pop eax ; store new EFLAGS in EAX
xor eax, ecx ; can’t toggle AC bit, processor=80386
jz end_cpu_is_386 ; jump if 80386 processor
push ecx
popfd ; restore AC bit in EFLAGS first
pushfd
pushfd
pop ecx
mov eax, ecx ; get original EFLAGS
xor eax, 200000h ; flip ID bit in EFLAGS
push eax ; save new EFLAGS value on stack
popfd ; replace current EFLAGS value
pushfd ; get new EFLAGS
pop eax ; store new EFLAGS in EAX
popfd ; restore original EFLAGS
xor eax, ecx ; can’t toggle ID bit,
je is_old_486 ; processor=old
mov eax,1
db 0fh,0a2h ;CPUID
exitcpudetect:
pop ebx
ret
end_cpu_is_386:
mov eax,0300h
jmp exitcpudetect
is_old_486:
mov eax,0400h
jmp exitcpudetect
IFDEF NOUNDERLINE
cpudetect32 endp
ELSE
_cpudetect32 endp
ENDIF
ENDIF
MAX_MATCH equ 258
MIN_MATCH equ 3
MIN_LOOKAHEAD equ (MAX_MATCH + MIN_MATCH + 1)
MAX_MATCH_8_ equ ((MAX_MATCH + 7) AND 0FFF0h)
;;; stack frame offsets
chainlenwmask equ esp + 0 ; high word: current chain len
; low word: s->wmask
window equ esp + 4 ; local copy of s->window
windowbestlen equ esp + 8 ; s->window + bestlen
scanstart equ esp + 16 ; first two bytes of string
scanend equ esp + 12 ; last two bytes of string
scanalign equ esp + 20 ; dword-misalignment of string
nicematch equ esp + 24 ; a good enough match size
bestlen equ esp + 28 ; size of best match so far
scan equ esp + 32 ; ptr to string wanting match
LocalVarsSize equ 36
; saved ebx byte esp + 36
; saved edi byte esp + 40
; saved esi byte esp + 44
; saved ebp byte esp + 48
; return address byte esp + 52
deflatestate equ esp + 56 ; the function arguments
curmatch equ esp + 60
;;; Offsets for fields in the deflate_state structure. These numbers
;;; are calculated from the definition of deflate_state, with the
;;; assumption that the compiler will dword-align the fields. (Thus,
;;; changing the definition of deflate_state could easily cause this
;;; program to crash horribly, without so much as a warning at
;;; compile time. Sigh.)
dsWSize equ 36+zlib1222add
dsWMask equ 44+zlib1222add
dsWindow equ 48+zlib1222add
dsPrev equ 56+zlib1222add
dsMatchLen equ 88+zlib1222add
dsPrevMatch equ 92+zlib1222add
dsStrStart equ 100+zlib1222add
dsMatchStart equ 104+zlib1222add
dsLookahead equ 108+zlib1222add
dsPrevLen equ 112+zlib1222add
dsMaxChainLen equ 116+zlib1222add
dsGoodMatch equ 132+zlib1222add
dsNiceMatch equ 136+zlib1222add
;;; match.asm -- Pentium-Pro-optimized version of longest_match()
;;; Written for zlib 1.1.2
;;; Copyright (C) 1998 Brian Raiter <breadbox@muppetlabs.com>
;;; You can look at http://www.muppetlabs.com/~breadbox/software/assembly.html
;;;
;;; This is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License.
;GLOBAL _longest_match, _match_init
;SECTION .text
;;; uInt longest_match(deflate_state *deflatestate, IPos curmatch)
;_longest_match:
IFDEF NOOLDPENTIUMCODE
IFDEF NOUNDERLINE
longest_match proc near
ELSE
_longest_match proc near
ENDIF
ELSE
IFDEF NOUNDERLINE
longest_match_686 proc near
ELSE
_longest_match_686 proc near
ENDIF
ENDIF
;;; Save registers that the compiler may be using, and adjust esp to
;;; make room for our stack frame.
push ebp
push edi
push esi
push ebx
sub esp, LocalVarsSize
;;; Retrieve the function arguments. ecx will hold cur_match
;;; throughout the entire function. edx will hold the pointer to the
;;; deflate_state structure during the function's setup (before
;;; entering the main loop.
mov edx, [deflatestate]
mov ecx, [curmatch]
;;; uInt wmask = s->w_mask;
;;; unsigned chain_length = s->max_chain_length;
;;; if (s->prev_length >= s->good_match) {
;;; chain_length >>= 2;
;;; }
mov eax, [edx + dsPrevLen]
mov ebx, [edx + dsGoodMatch]
cmp eax, ebx
mov eax, [edx + dsWMask]
mov ebx, [edx + dsMaxChainLen]
jl LastMatchGood
shr ebx, 2
LastMatchGood:
;;; chainlen is decremented once beforehand so that the function can
;;; use the sign flag instead of the zero flag for the exit test.
;;; It is then shifted into the high word, to make room for the wmask
;;; value, which it will always accompany.
dec ebx
shl ebx, 16
or ebx, eax
mov [chainlenwmask], ebx
;;; if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
mov eax, [edx + dsNiceMatch]
mov ebx, [edx + dsLookahead]
cmp ebx, eax
jl LookaheadLess
mov ebx, eax
LookaheadLess: mov [nicematch], ebx
;;; register Bytef *scan = s->window + s->strstart;
mov esi, [edx + dsWindow]
mov [window], esi
mov ebp, [edx + dsStrStart]
lea edi, [esi + ebp]
mov [scan], edi
;;; Determine how many bytes the scan ptr is off from being
;;; dword-aligned.
mov eax, edi
neg eax
and eax, 3
mov [scanalign], eax
;;; IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
;;; s->strstart - (IPos)MAX_DIST(s) : NIL;
mov eax, [edx + dsWSize]
sub eax, MIN_LOOKAHEAD
sub ebp, eax
jg LimitPositive
xor ebp, ebp
LimitPositive:
;;; int best_len = s->prev_length;
mov eax, [edx + dsPrevLen]
mov [bestlen], eax
;;; Store the sum of s->window + best_len in esi locally, and in esi.
add esi, eax
mov [windowbestlen], esi
;;; register ush scan_start = *(ushf*)scan;
;;; register ush scan_end = *(ushf*)(scan+best_len-1);
;;; Posf *prev = s->prev;
movzx ebx, word ptr [edi]
mov [scanstart], ebx
movzx ebx, word ptr [edi + eax - 1]
mov [scanend], ebx
mov edi, [edx + dsPrev]
;;; Jump into the main loop.
mov edx, [chainlenwmask]
jmp short LoopEntry
align 4
;;; do {
;;; match = s->window + cur_match;
;;; if (*(ushf*)(match+best_len-1) != scan_end ||
;;; *(ushf*)match != scan_start) continue;
;;; [...]
;;; } while ((cur_match = prev[cur_match & wmask]) > limit
;;; && --chain_length != 0);
;;;
;;; Here is the inner loop of the function. The function will spend the
;;; majority of its time in this loop, and majority of that time will
;;; be spent in the first ten instructions.
;;;
;;; Within this loop:
;;; ebx = scanend
;;; ecx = curmatch
;;; edx = chainlenwmask - i.e., ((chainlen << 16) | wmask)
;;; esi = windowbestlen - i.e., (window + bestlen)
;;; edi = prev
;;; ebp = limit
LookupLoop:
and ecx, edx
movzx ecx, word ptr [edi + ecx*2]
cmp ecx, ebp
jbe LeaveNow
sub edx, 00010000h
js LeaveNow
LoopEntry: movzx eax, word ptr [esi + ecx - 1]
cmp eax, ebx
jnz LookupLoop
mov eax, [window]
movzx eax, word ptr [eax + ecx]
cmp eax, [scanstart]
jnz LookupLoop
;;; Store the current value of chainlen.
mov [chainlenwmask], edx
;;; Point edi to the string under scrutiny, and esi to the string we
;;; are hoping to match it up with. In actuality, esi and edi are
;;; both pointed (MAX_MATCH_8 - scanalign) bytes ahead, and edx is
;;; initialized to -(MAX_MATCH_8 - scanalign).
mov esi, [window]
mov edi, [scan]
add esi, ecx
mov eax, [scanalign]
mov edx, 0fffffef8h; -(MAX_MATCH_8)
lea edi, [edi + eax + 0108h] ;MAX_MATCH_8]
lea esi, [esi + eax + 0108h] ;MAX_MATCH_8]
;;; Test the strings for equality, 8 bytes at a time. At the end,
;;; adjust edx so that it is offset to the exact byte that mismatched.
;;;
;;; We already know at this point that the first three bytes of the
;;; strings match each other, and they can be safely passed over before
;;; starting the compare loop. So what this code does is skip over 0-3
;;; bytes, as much as necessary in order to dword-align the edi
;;; pointer. (esi will still be misaligned three times out of four.)
;;;
;;; It should be confessed that this loop usually does not represent
;;; much of the total running time. Replacing it with a more
;;; straightforward "rep cmpsb" would not drastically degrade
;;; performance.
LoopCmps:
mov eax, [esi + edx]
xor eax, [edi + edx]
jnz LeaveLoopCmps
mov eax, [esi + edx + 4]
xor eax, [edi + edx + 4]
jnz LeaveLoopCmps4
add edx, 8
jnz LoopCmps
jmp short LenMaximum
LeaveLoopCmps4: add edx, 4
LeaveLoopCmps: test eax, 0000FFFFh
jnz LenLower
add edx, 2
shr eax, 16
LenLower: sub al, 1
adc edx, 0
;;; Calculate the length of the match. If it is longer than MAX_MATCH,
;;; then automatically accept it as the best possible match and leave.
lea eax, [edi + edx]
mov edi, [scan]
sub eax, edi
cmp eax, MAX_MATCH
jge LenMaximum
;;; If the length of the match is not longer than the best match we
;;; have so far, then forget it and return to the lookup loop.
mov edx, [deflatestate]
mov ebx, [bestlen]
cmp eax, ebx
jg LongerMatch
mov esi, [windowbestlen]
mov edi, [edx + dsPrev]
mov ebx, [scanend]
mov edx, [chainlenwmask]
jmp LookupLoop
;;; s->match_start = cur_match;
;;; best_len = len;
;;; if (len >= nice_match) break;
;;; scan_end = *(ushf*)(scan+best_len-1);
LongerMatch: mov ebx, [nicematch]
mov [bestlen], eax
mov [edx + dsMatchStart], ecx
cmp eax, ebx
jge LeaveNow
mov esi, [window]
add esi, eax
mov [windowbestlen], esi
movzx ebx, word ptr [edi + eax - 1]
mov edi, [edx + dsPrev]
mov [scanend], ebx
mov edx, [chainlenwmask]
jmp LookupLoop
;;; Accept the current string, with the maximum possible length.
LenMaximum: mov edx, [deflatestate]
mov dword ptr [bestlen], MAX_MATCH
mov [edx + dsMatchStart], ecx
;;; if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
;;; return s->lookahead;
LeaveNow:
mov edx, [deflatestate]
mov ebx, [bestlen]
mov eax, [edx + dsLookahead]
cmp ebx, eax
jg LookaheadRet
mov eax, ebx
LookaheadRet:
;;; Restore the stack and return from whence we came.
add esp, LocalVarsSize
pop ebx
pop esi
pop edi
pop ebp
ret
; please don't remove this string !
; Your can freely use gvmat32 in any free or commercial app if you don't remove the string in the binary!
db 0dh,0ah,"asm686 with masm, optimised assembly code from Brian Raiter, written 1998",0dh,0ah
IFDEF NOOLDPENTIUMCODE
IFDEF NOUNDERLINE
longest_match endp
ELSE
_longest_match endp
ENDIF
IFDEF NOUNDERLINE
match_init proc near
ret
match_init endp
ELSE
_match_init proc near
ret
_match_init endp
ENDIF
ELSE
IFDEF NOUNDERLINE
longest_match_686 endp
ELSE
_longest_match_686 endp
ENDIF
ENDIF
_TEXT ends
end