diff options
Diffstat (limited to 'zlib/contrib/masm686/match.asm')
| -rw-r--r-- | zlib/contrib/masm686/match.asm | 821 |
1 files changed, 413 insertions, 408 deletions
diff --git a/zlib/contrib/masm686/match.asm b/zlib/contrib/masm686/match.asm index 2287804d443..4b03a71abd5 100644 --- a/zlib/contrib/masm686/match.asm +++ b/zlib/contrib/masm686/match.asm @@ -1,408 +1,413 @@ - -; match.asm -- Pentium-Pro optimized version of longest_match() -; -; Updated for zlib 1.1.3 and converted to MASM 6.1x -; Copyright (C) 2000 Dan Higdon <hdan@kinesoft.com> -; and Chuck Walbourn <chuckw@kinesoft.com> -; Corrections by Cosmin Truta <cosmint@cs.ubbcluj.ro> -; -; This is free software; you can redistribute it and/or modify it -; under the terms of the GNU General Public License. - -; Based on match.S -; Written for zlib 1.1.2 -; Copyright (C) 1998 Brian Raiter <breadbox@muppetlabs.com> - - .686P - .MODEL FLAT - -;=========================================================================== -; EQUATES -;=========================================================================== - -MAX_MATCH EQU 258 -MIN_MATCH EQU 3 -MIN_LOOKAHEAD EQU (MAX_MATCH + MIN_MATCH + 1) -MAX_MATCH_8 EQU ((MAX_MATCH + 7) AND (NOT 7)) - -;=========================================================================== -; STRUCTURES -;=========================================================================== - -; This STRUCT assumes a 4-byte alignment - -DEFLATE_STATE STRUCT -ds_strm dd ? -ds_status dd ? -ds_pending_buf dd ? -ds_pending_buf_size dd ? -ds_pending_out dd ? -ds_pending dd ? -ds_wrap dd ? -ds_data_type db ? -ds_method db ? - db ? ; padding - db ? ; padding -ds_last_flush dd ? -ds_w_size dd ? ; used -ds_w_bits dd ? -ds_w_mask dd ? ; used -ds_window dd ? ; used -ds_window_size dd ? -ds_prev dd ? ; used -ds_head dd ? -ds_ins_h dd ? -ds_hash_size dd ? -ds_hash_bits dd ? -ds_hash_mask dd ? -ds_hash_shift dd ? -ds_block_start dd ? -ds_match_length dd ? ; used -ds_prev_match dd ? ; used -ds_match_available dd ? -ds_strstart dd ? ; used -ds_match_start dd ? ; used -ds_lookahead dd ? ; used -ds_prev_length dd ? ; used -ds_max_chain_length dd ? ; used -ds_max_laxy_match dd ? -ds_level dd ? -ds_strategy dd ? -ds_good_match dd ? ; used -ds_nice_match dd ? ; used - -; Don't need anymore of the struct for match -DEFLATE_STATE ENDS - -;=========================================================================== -; CODE -;=========================================================================== -_TEXT SEGMENT - -;--------------------------------------------------------------------------- -; match_init -;--------------------------------------------------------------------------- - ALIGN 4 -PUBLIC _match_init -_match_init PROC - ; no initialization needed - ret -_match_init ENDP - -;--------------------------------------------------------------------------- -; uInt longest_match(deflate_state *deflatestate, IPos curmatch) -;--------------------------------------------------------------------------- - ALIGN 4 - -PUBLIC _longest_match -_longest_match PROC - -; Since this code uses EBP for a scratch register, the stack frame must -; be manually constructed and referenced relative to the ESP register. - -; Stack image -; Variables -chainlenwmask = 0 ; high word: current chain len - ; low word: s->wmask -window = 4 ; local copy of s->window -windowbestlen = 8 ; s->window + bestlen -scanend = 12 ; last two bytes of string -scanstart = 16 ; first two bytes of string -scanalign = 20 ; dword-misalignment of string -nicematch = 24 ; a good enough match size -bestlen = 28 ; size of best match so far -scan = 32 ; ptr to string wanting match -varsize = 36 ; number of bytes (also offset to last saved register) - -; Saved Registers (actually pushed into place) -ebx_save = 36 -edi_save = 40 -esi_save = 44 -ebp_save = 48 - -; Parameters -retaddr = 52 -deflatestate = 56 -curmatch = 60 - -; Save registers that the compiler may be using - push ebp - push edi - push esi - push ebx - -; Allocate local variable space - sub esp,varsize - -; 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, [esp+deflatestate] -ASSUME edx:PTR DEFLATE_STATE - - mov ecx, [esp+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].ds_prev_length - mov ebx, [edx].ds_good_match - cmp eax, ebx - mov eax, [edx].ds_w_mask - mov ebx, [edx].ds_max_chain_length - jl SHORT 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 [esp+chainlenwmask], ebx - -; if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead; - - mov eax, [edx].ds_nice_match - mov ebx, [edx].ds_lookahead - cmp ebx, eax - jl SHORT LookaheadLess - mov ebx, eax -LookaheadLess: - mov [esp+nicematch], ebx - -;/* register Bytef *scan = s->window + s->strstart; */ - - mov esi, [edx].ds_window - mov [esp+window], esi - mov ebp, [edx].ds_strstart - lea edi, [esi+ebp] - mov [esp+scan],edi - -;/* Determine how many bytes the scan ptr is off from being */ -;/* dword-aligned. */ - - mov eax, edi - neg eax - and eax, 3 - mov [esp+scanalign], eax - -;/* IPos limit = s->strstart > (IPos)MAX_DIST(s) ? */ -;/* s->strstart - (IPos)MAX_DIST(s) : NIL; */ - - mov eax, [edx].ds_w_size - sub eax, MIN_LOOKAHEAD - sub ebp, eax - jg SHORT LimitPositive - xor ebp, ebp -LimitPositive: - -;/* int best_len = s->prev_length; */ - - mov eax, [edx].ds_prev_length - mov [esp+bestlen], eax - -;/* Store the sum of s->window + best_len in %esi locally, and in %esi. */ - - add esi, eax - mov [esp+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 [esp+scanstart], ebx - movzx ebx, WORD PTR[eax+edi-1] - mov [esp+scanend], ebx - mov edi, [edx].ds_prev - -;/* Jump into the main loop. */ - - mov edx, [esp+chainlenwmask] - jmp SHORT LoopEntry - -;/* 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 -; */ - - ALIGN 4 -LookupLoop: - and ecx, edx - movzx ecx, WORD PTR[edi+ecx*2] - cmp ecx, ebp - jbe LeaveNow - sub edx, 000010000H - js LeaveNow - -LoopEntry: - movzx eax, WORD PTR[esi+ecx-1] - cmp eax, ebx - jnz SHORT LookupLoop - - mov eax, [esp+window] - movzx eax, WORD PTR[eax+ecx] - cmp eax, [esp+scanstart] - jnz SHORT LookupLoop - -;/* Store the current value of chainlen. */ - - mov [esp+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, [esp+window] - mov edi, [esp+scan] - add esi, ecx - mov eax, [esp+scanalign] - mov edx, -MAX_MATCH_8 - lea edi, [edi+eax+MAX_MATCH_8] - lea esi, [esi+eax+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, DWORD PTR[esi+edx] - xor eax, DWORD PTR[edi+edx] - jnz SHORT LeaveLoopCmps - - mov eax, DWORD PTR[esi+edx+4] - xor eax, DWORD PTR[edi+edx+4] - jnz SHORT LeaveLoopCmps4 - - add edx, 8 - jnz SHORT LoopCmps - jmp LenMaximum - ALIGN 4 - -LeaveLoopCmps4: - add edx, 4 - -LeaveLoopCmps: - test eax, 00000FFFFH - jnz SHORT 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, [esp+scan] - sub eax, edi - cmp eax, MAX_MATCH - jge SHORT 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, [esp+deflatestate] - mov ebx, [esp+bestlen] - cmp eax, ebx - jg SHORT LongerMatch - mov esi, [esp+windowbestlen] - mov edi, [edx].ds_prev - mov ebx, [esp+scanend] - mov edx, [esp+chainlenwmask] - jmp LookupLoop - ALIGN 4 - -;/* s->match_start = cur_match; */ -;/* best_len = len; */ -;/* if (len >= nice_match) break; */ -;/* scan_end = *(ushf*)(scan+best_len-1); */ - -LongerMatch: - mov ebx, [esp+nicematch] - mov [esp+bestlen], eax - mov [edx].ds_match_start, ecx - cmp eax, ebx - jge SHORT LeaveNow - mov esi, [esp+window] - add esi, eax - mov [esp+windowbestlen], esi - movzx ebx, WORD PTR[edi+eax-1] - mov edi, [edx].ds_prev - mov [esp+scanend], ebx - mov edx, [esp+chainlenwmask] - jmp LookupLoop - ALIGN 4 - -;/* Accept the current string, with the maximum possible length. */ - -LenMaximum: - mov edx, [esp+deflatestate] - mov DWORD PTR[esp+bestlen], MAX_MATCH - mov [edx].ds_match_start, ecx - -;/* if ((uInt)best_len <= s->lookahead) return (uInt)best_len; */ -;/* return s->lookahead; */ - -LeaveNow: - mov edx, [esp+deflatestate] - mov ebx, [esp+bestlen] - mov eax, [edx].ds_lookahead - cmp ebx, eax - jg SHORT LookaheadRet - mov eax, ebx -LookaheadRet: - -; Restore the stack and return from whence we came. - - add esp, varsize - pop ebx - pop esi - pop edi - pop ebp - ret - -_longest_match ENDP - -_TEXT ENDS -END +
+; match.asm -- Pentium-Pro optimized version of longest_match()
+;
+; Updated for zlib 1.1.3 and converted to MASM 6.1x
+; Copyright (C) 2000 Dan Higdon <hdan@kinesoft.com>
+; and Chuck Walbourn <chuckw@kinesoft.com>
+; Corrections by Cosmin Truta <cosmint@cs.ubbcluj.ro>
+;
+; This is free software; you can redistribute it and/or modify it
+; under the terms of the GNU General Public License.
+
+; Based on match.S
+; Written for zlib 1.1.2
+; Copyright (C) 1998 Brian Raiter <breadbox@muppetlabs.com>
+;
+; Modified by Gilles Vollant (2005) for add gzhead and gzindex
+
+ .686P
+ .MODEL FLAT
+
+;===========================================================================
+; EQUATES
+;===========================================================================
+
+MAX_MATCH EQU 258
+MIN_MATCH EQU 3
+MIN_LOOKAHEAD EQU (MAX_MATCH + MIN_MATCH + 1)
+MAX_MATCH_8 EQU ((MAX_MATCH + 7) AND (NOT 7))
+
+;===========================================================================
+; STRUCTURES
+;===========================================================================
+
+; This STRUCT assumes a 4-byte alignment
+
+DEFLATE_STATE STRUCT
+ds_strm dd ?
+ds_status dd ?
+ds_pending_buf dd ?
+ds_pending_buf_size dd ?
+ds_pending_out dd ?
+ds_pending dd ?
+ds_wrap dd ?
+; gzhead and gzindex are added in zlib 1.2.2.2 (see deflate.h)
+ds_gzhead dd ?
+ds_gzindex dd ?
+ds_data_type db ?
+ds_method db ?
+ db ? ; padding
+ db ? ; padding
+ds_last_flush dd ?
+ds_w_size dd ? ; used
+ds_w_bits dd ?
+ds_w_mask dd ? ; used
+ds_window dd ? ; used
+ds_window_size dd ?
+ds_prev dd ? ; used
+ds_head dd ?
+ds_ins_h dd ?
+ds_hash_size dd ?
+ds_hash_bits dd ?
+ds_hash_mask dd ?
+ds_hash_shift dd ?
+ds_block_start dd ?
+ds_match_length dd ? ; used
+ds_prev_match dd ? ; used
+ds_match_available dd ?
+ds_strstart dd ? ; used
+ds_match_start dd ? ; used
+ds_lookahead dd ? ; used
+ds_prev_length dd ? ; used
+ds_max_chain_length dd ? ; used
+ds_max_laxy_match dd ?
+ds_level dd ?
+ds_strategy dd ?
+ds_good_match dd ? ; used
+ds_nice_match dd ? ; used
+
+; Don't need anymore of the struct for match
+DEFLATE_STATE ENDS
+
+;===========================================================================
+; CODE
+;===========================================================================
+_TEXT SEGMENT
+
+;---------------------------------------------------------------------------
+; match_init
+;---------------------------------------------------------------------------
+ ALIGN 4
+PUBLIC _match_init
+_match_init PROC
+ ; no initialization needed
+ ret
+_match_init ENDP
+
+;---------------------------------------------------------------------------
+; uInt longest_match(deflate_state *deflatestate, IPos curmatch)
+;---------------------------------------------------------------------------
+ ALIGN 4
+
+PUBLIC _longest_match
+_longest_match PROC
+
+; Since this code uses EBP for a scratch register, the stack frame must
+; be manually constructed and referenced relative to the ESP register.
+
+; Stack image
+; Variables
+chainlenwmask = 0 ; high word: current chain len
+ ; low word: s->wmask
+window = 4 ; local copy of s->window
+windowbestlen = 8 ; s->window + bestlen
+scanend = 12 ; last two bytes of string
+scanstart = 16 ; first two bytes of string
+scanalign = 20 ; dword-misalignment of string
+nicematch = 24 ; a good enough match size
+bestlen = 28 ; size of best match so far
+scan = 32 ; ptr to string wanting match
+varsize = 36 ; number of bytes (also offset to last saved register)
+
+; Saved Registers (actually pushed into place)
+ebx_save = 36
+edi_save = 40
+esi_save = 44
+ebp_save = 48
+
+; Parameters
+retaddr = 52
+deflatestate = 56
+curmatch = 60
+
+; Save registers that the compiler may be using
+ push ebp
+ push edi
+ push esi
+ push ebx
+
+; Allocate local variable space
+ sub esp,varsize
+
+; 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, [esp+deflatestate]
+ASSUME edx:PTR DEFLATE_STATE
+
+ mov ecx, [esp+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].ds_prev_length
+ mov ebx, [edx].ds_good_match
+ cmp eax, ebx
+ mov eax, [edx].ds_w_mask
+ mov ebx, [edx].ds_max_chain_length
+ jl SHORT 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 [esp+chainlenwmask], ebx
+
+; if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
+
+ mov eax, [edx].ds_nice_match
+ mov ebx, [edx].ds_lookahead
+ cmp ebx, eax
+ jl SHORT LookaheadLess
+ mov ebx, eax
+LookaheadLess:
+ mov [esp+nicematch], ebx
+
+;/* register Bytef *scan = s->window + s->strstart; */
+
+ mov esi, [edx].ds_window
+ mov [esp+window], esi
+ mov ebp, [edx].ds_strstart
+ lea edi, [esi+ebp]
+ mov [esp+scan],edi
+
+;/* Determine how many bytes the scan ptr is off from being */
+;/* dword-aligned. */
+
+ mov eax, edi
+ neg eax
+ and eax, 3
+ mov [esp+scanalign], eax
+
+;/* IPos limit = s->strstart > (IPos)MAX_DIST(s) ? */
+;/* s->strstart - (IPos)MAX_DIST(s) : NIL; */
+
+ mov eax, [edx].ds_w_size
+ sub eax, MIN_LOOKAHEAD
+ sub ebp, eax
+ jg SHORT LimitPositive
+ xor ebp, ebp
+LimitPositive:
+
+;/* int best_len = s->prev_length; */
+
+ mov eax, [edx].ds_prev_length
+ mov [esp+bestlen], eax
+
+;/* Store the sum of s->window + best_len in %esi locally, and in %esi. */
+
+ add esi, eax
+ mov [esp+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 [esp+scanstart], ebx
+ movzx ebx, WORD PTR[eax+edi-1]
+ mov [esp+scanend], ebx
+ mov edi, [edx].ds_prev
+
+;/* Jump into the main loop. */
+
+ mov edx, [esp+chainlenwmask]
+ jmp SHORT LoopEntry
+
+;/* 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
+; */
+
+ ALIGN 4
+LookupLoop:
+ and ecx, edx
+ movzx ecx, WORD PTR[edi+ecx*2]
+ cmp ecx, ebp
+ jbe LeaveNow
+ sub edx, 000010000H
+ js LeaveNow
+
+LoopEntry:
+ movzx eax, WORD PTR[esi+ecx-1]
+ cmp eax, ebx
+ jnz SHORT LookupLoop
+
+ mov eax, [esp+window]
+ movzx eax, WORD PTR[eax+ecx]
+ cmp eax, [esp+scanstart]
+ jnz SHORT LookupLoop
+
+;/* Store the current value of chainlen. */
+
+ mov [esp+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, [esp+window]
+ mov edi, [esp+scan]
+ add esi, ecx
+ mov eax, [esp+scanalign]
+ mov edx, -MAX_MATCH_8
+ lea edi, [edi+eax+MAX_MATCH_8]
+ lea esi, [esi+eax+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, DWORD PTR[esi+edx]
+ xor eax, DWORD PTR[edi+edx]
+ jnz SHORT LeaveLoopCmps
+
+ mov eax, DWORD PTR[esi+edx+4]
+ xor eax, DWORD PTR[edi+edx+4]
+ jnz SHORT LeaveLoopCmps4
+
+ add edx, 8
+ jnz SHORT LoopCmps
+ jmp LenMaximum
+ ALIGN 4
+
+LeaveLoopCmps4:
+ add edx, 4
+
+LeaveLoopCmps:
+ test eax, 00000FFFFH
+ jnz SHORT 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, [esp+scan]
+ sub eax, edi
+ cmp eax, MAX_MATCH
+ jge SHORT 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, [esp+deflatestate]
+ mov ebx, [esp+bestlen]
+ cmp eax, ebx
+ jg SHORT LongerMatch
+ mov esi, [esp+windowbestlen]
+ mov edi, [edx].ds_prev
+ mov ebx, [esp+scanend]
+ mov edx, [esp+chainlenwmask]
+ jmp LookupLoop
+ ALIGN 4
+
+;/* s->match_start = cur_match; */
+;/* best_len = len; */
+;/* if (len >= nice_match) break; */
+;/* scan_end = *(ushf*)(scan+best_len-1); */
+
+LongerMatch:
+ mov ebx, [esp+nicematch]
+ mov [esp+bestlen], eax
+ mov [edx].ds_match_start, ecx
+ cmp eax, ebx
+ jge SHORT LeaveNow
+ mov esi, [esp+window]
+ add esi, eax
+ mov [esp+windowbestlen], esi
+ movzx ebx, WORD PTR[edi+eax-1]
+ mov edi, [edx].ds_prev
+ mov [esp+scanend], ebx
+ mov edx, [esp+chainlenwmask]
+ jmp LookupLoop
+ ALIGN 4
+
+;/* Accept the current string, with the maximum possible length. */
+
+LenMaximum:
+ mov edx, [esp+deflatestate]
+ mov DWORD PTR[esp+bestlen], MAX_MATCH
+ mov [edx].ds_match_start, ecx
+
+;/* if ((uInt)best_len <= s->lookahead) return (uInt)best_len; */
+;/* return s->lookahead; */
+
+LeaveNow:
+ mov edx, [esp+deflatestate]
+ mov ebx, [esp+bestlen]
+ mov eax, [edx].ds_lookahead
+ cmp ebx, eax
+ jg SHORT LookaheadRet
+ mov eax, ebx
+LookaheadRet:
+
+; Restore the stack and return from whence we came.
+
+ add esp, varsize
+ pop ebx
+ pop esi
+ pop edi
+ pop ebp
+ ret
+
+_longest_match ENDP
+
+_TEXT ENDS
+END
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