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973 lines
26 KiB
NASM
973 lines
26 KiB
NASM
; gvmat32.asm -- Asm portion of the optimized longest_match for 32 bits x86
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; Copyright (C) 1995-1996 Jean-loup Gailly and Gilles Vollant.
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; File written by Gilles Vollant, by modifiying the longest_match
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; from Jean-loup Gailly in deflate.c
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;
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; http://www.zlib.net
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; http://www.winimage.com/zLibDll
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; http://www.muppetlabs.com/~breadbox/software/assembly.html
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;
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; For Visual C++ 4.x and higher and ML 6.x and higher
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; ml.exe is in directory \MASM611C of Win95 DDK
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; ml.exe is also distributed in http://www.masm32.com/masmdl.htm
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; and in VC++2003 toolkit at http://msdn.microsoft.com/visualc/vctoolkit2003/
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;
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; this file contain two implementation of longest_match
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;
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; longest_match_7fff : written 1996 by Gilles Vollant optimized for
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; first Pentium. Assume s->w_mask == 0x7fff
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; longest_match_686 : written by Brian raiter (1998), optimized for Pentium Pro
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;
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; for using an seembly version of longest_match, you need define ASMV in project
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; There is two way in using gvmat32.asm
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;
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; A) Suggested method
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; if you want include both longest_match_7fff and longest_match_686
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; compile the asm file running
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; ml /coff /Zi /Flgvmat32.lst /c gvmat32.asm
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; and include gvmat32c.c in your project
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; if you have an old cpu (386,486 or first Pentium) and s->w_mask==0x7fff,
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; longest_match_7fff will be used
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; if you have a more modern CPU (Pentium Pro, II and higher)
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; longest_match_686 will be used
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; on old cpu with s->w_mask!=0x7fff, longest_match_686 will be used,
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; but this is not a sitation you'll find often
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;
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; B) Alternative
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; if you are not interresed in old cpu performance and want the smaller
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; binaries possible
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;
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; compile the asm file running
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; ml /coff /Zi /c /Flgvmat32.lst /DNOOLDPENTIUMCODE gvmat32.asm
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; and do not include gvmat32c.c in your project (ou define also
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; NOOLDPENTIUMCODE)
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;
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; note : as I known, longest_match_686 is very faster than longest_match_7fff
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; on pentium Pro/II/III, faster (but less) in P4, but it seem
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; longest_match_7fff can be faster (very very litte) on AMD Athlon64/K8
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;
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; see below : zlib1222add must be adjuster if you use a zlib version < 1.2.2.2
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;uInt longest_match_7fff(s, cur_match)
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; deflate_state *s;
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; IPos cur_match; /* current match */
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NbStack equ 76
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cur_match equ dword ptr[esp+NbStack-0]
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str_s equ dword ptr[esp+NbStack-4]
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; 5 dword on top (ret,ebp,esi,edi,ebx)
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adrret equ dword ptr[esp+NbStack-8]
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pushebp equ dword ptr[esp+NbStack-12]
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pushedi equ dword ptr[esp+NbStack-16]
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pushesi equ dword ptr[esp+NbStack-20]
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pushebx equ dword ptr[esp+NbStack-24]
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chain_length equ dword ptr [esp+NbStack-28]
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limit equ dword ptr [esp+NbStack-32]
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best_len equ dword ptr [esp+NbStack-36]
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window equ dword ptr [esp+NbStack-40]
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prev equ dword ptr [esp+NbStack-44]
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scan_start equ word ptr [esp+NbStack-48]
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wmask equ dword ptr [esp+NbStack-52]
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match_start_ptr equ dword ptr [esp+NbStack-56]
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nice_match equ dword ptr [esp+NbStack-60]
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scan equ dword ptr [esp+NbStack-64]
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windowlen equ dword ptr [esp+NbStack-68]
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match_start equ dword ptr [esp+NbStack-72]
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strend equ dword ptr [esp+NbStack-76]
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NbStackAdd equ (NbStack-24)
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.386p
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name gvmatch
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.MODEL FLAT
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; all the +zlib1222add offsets are due to the addition of fields
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; in zlib in the deflate_state structure since the asm code was first written
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; (if you compile with zlib 1.0.4 or older, use "zlib1222add equ (-4)").
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; (if you compile with zlib between 1.0.5 and 1.2.2.1, use "zlib1222add equ 0").
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; if you compile with zlib 1.2.2.2 or later , use "zlib1222add equ 8").
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zlib1222add equ 8
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; Note : these value are good with a 8 bytes boundary pack structure
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dep_chain_length equ 74h+zlib1222add
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dep_window equ 30h+zlib1222add
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dep_strstart equ 64h+zlib1222add
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dep_prev_length equ 70h+zlib1222add
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dep_nice_match equ 88h+zlib1222add
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dep_w_size equ 24h+zlib1222add
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dep_prev equ 38h+zlib1222add
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dep_w_mask equ 2ch+zlib1222add
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dep_good_match equ 84h+zlib1222add
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dep_match_start equ 68h+zlib1222add
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dep_lookahead equ 6ch+zlib1222add
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_TEXT segment
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IFDEF NOUNDERLINE
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IFDEF NOOLDPENTIUMCODE
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public longest_match
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public match_init
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ELSE
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public longest_match_7fff
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public cpudetect32
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public longest_match_686
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ENDIF
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ELSE
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IFDEF NOOLDPENTIUMCODE
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public _longest_match
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public _match_init
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ELSE
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public _longest_match_7fff
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public _cpudetect32
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public _longest_match_686
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ENDIF
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ENDIF
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MAX_MATCH equ 258
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MIN_MATCH equ 3
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MIN_LOOKAHEAD equ (MAX_MATCH+MIN_MATCH+1)
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IFNDEF NOOLDPENTIUMCODE
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IFDEF NOUNDERLINE
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longest_match_7fff proc near
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ELSE
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_longest_match_7fff proc near
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ENDIF
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mov edx,[esp+4]
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push ebp
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push edi
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push esi
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push ebx
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sub esp,NbStackAdd
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; initialize or check the variables used in match.asm.
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mov ebp,edx
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; chain_length = s->max_chain_length
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; if (prev_length>=good_match) chain_length >>= 2
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mov edx,[ebp+dep_chain_length]
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mov ebx,[ebp+dep_prev_length]
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cmp [ebp+dep_good_match],ebx
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ja noshr
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shr edx,2
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noshr:
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; we increment chain_length because in the asm, the --chain_lenght is in the beginning of the loop
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inc edx
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mov edi,[ebp+dep_nice_match]
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mov chain_length,edx
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mov eax,[ebp+dep_lookahead]
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cmp eax,edi
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; if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
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jae nolookaheadnicematch
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mov edi,eax
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nolookaheadnicematch:
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; best_len = s->prev_length
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mov best_len,ebx
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; window = s->window
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mov esi,[ebp+dep_window]
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mov ecx,[ebp+dep_strstart]
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mov window,esi
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mov nice_match,edi
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; scan = window + strstart
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add esi,ecx
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mov scan,esi
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; dx = *window
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mov dx,word ptr [esi]
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; bx = *(window+best_len-1)
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mov bx,word ptr [esi+ebx-1]
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add esi,MAX_MATCH-1
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; scan_start = *scan
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mov scan_start,dx
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; strend = scan + MAX_MATCH-1
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mov strend,esi
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; bx = scan_end = *(window+best_len-1)
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; IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
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; s->strstart - (IPos)MAX_DIST(s) : NIL;
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mov esi,[ebp+dep_w_size]
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sub esi,MIN_LOOKAHEAD
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; here esi = MAX_DIST(s)
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sub ecx,esi
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ja nodist
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xor ecx,ecx
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nodist:
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mov limit,ecx
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; prev = s->prev
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mov edx,[ebp+dep_prev]
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mov prev,edx
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;
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mov edx,dword ptr [ebp+dep_match_start]
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mov bp,scan_start
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mov eax,cur_match
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mov match_start,edx
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mov edx,window
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mov edi,edx
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add edi,best_len
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mov esi,prev
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dec edi
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; windowlen = window + best_len -1
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mov windowlen,edi
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jmp beginloop2
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align 4
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; here, in the loop
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; eax = ax = cur_match
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; ecx = limit
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; bx = scan_end
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; bp = scan_start
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; edi = windowlen (window + best_len -1)
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; esi = prev
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;// here; chain_length <=16
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normalbeg0add16:
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add chain_length,16
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jz exitloop
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normalbeg0:
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cmp word ptr[edi+eax],bx
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je normalbeg2noroll
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rcontlabnoroll:
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; cur_match = prev[cur_match & wmask]
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and eax,7fffh
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mov ax,word ptr[esi+eax*2]
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; if cur_match > limit, go to exitloop
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cmp ecx,eax
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jnb exitloop
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; if --chain_length != 0, go to exitloop
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dec chain_length
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jnz normalbeg0
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jmp exitloop
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normalbeg2noroll:
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; if (scan_start==*(cur_match+window)) goto normalbeg2
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cmp bp,word ptr[edx+eax]
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jne rcontlabnoroll
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jmp normalbeg2
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contloop3:
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mov edi,windowlen
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; cur_match = prev[cur_match & wmask]
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and eax,7fffh
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mov ax,word ptr[esi+eax*2]
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; if cur_match > limit, go to exitloop
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cmp ecx,eax
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jnbexitloopshort1:
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jnb exitloop
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; if --chain_length != 0, go to exitloop
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; begin the main loop
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beginloop2:
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sub chain_length,16+1
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; if chain_length <=16, don't use the unrolled loop
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jna normalbeg0add16
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do16:
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cmp word ptr[edi+eax],bx
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je normalbeg2dc0
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maccn MACRO lab
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and eax,7fffh
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mov ax,word ptr[esi+eax*2]
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cmp ecx,eax
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jnb exitloop
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cmp word ptr[edi+eax],bx
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je lab
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ENDM
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rcontloop0:
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maccn normalbeg2dc1
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rcontloop1:
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maccn normalbeg2dc2
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rcontloop2:
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maccn normalbeg2dc3
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rcontloop3:
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maccn normalbeg2dc4
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rcontloop4:
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maccn normalbeg2dc5
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rcontloop5:
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maccn normalbeg2dc6
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rcontloop6:
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maccn normalbeg2dc7
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rcontloop7:
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maccn normalbeg2dc8
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rcontloop8:
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maccn normalbeg2dc9
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rcontloop9:
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maccn normalbeg2dc10
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rcontloop10:
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maccn short normalbeg2dc11
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rcontloop11:
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maccn short normalbeg2dc12
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rcontloop12:
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maccn short normalbeg2dc13
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rcontloop13:
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maccn short normalbeg2dc14
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rcontloop14:
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maccn short normalbeg2dc15
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rcontloop15:
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and eax,7fffh
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mov ax,word ptr[esi+eax*2]
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cmp ecx,eax
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jnb exitloop
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sub chain_length,16
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ja do16
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jmp normalbeg0add16
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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normbeg MACRO rcontlab,valsub
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; if we are here, we know that *(match+best_len-1) == scan_end
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cmp bp,word ptr[edx+eax]
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; if (match != scan_start) goto rcontlab
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jne rcontlab
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; calculate the good chain_length, and we'll compare scan and match string
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add chain_length,16-valsub
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jmp iseq
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ENDM
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normalbeg2dc11:
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normbeg rcontloop11,11
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normalbeg2dc12:
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normbeg short rcontloop12,12
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normalbeg2dc13:
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normbeg short rcontloop13,13
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normalbeg2dc14:
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normbeg short rcontloop14,14
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normalbeg2dc15:
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normbeg short rcontloop15,15
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normalbeg2dc10:
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normbeg rcontloop10,10
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normalbeg2dc9:
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normbeg rcontloop9,9
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normalbeg2dc8:
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normbeg rcontloop8,8
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normalbeg2dc7:
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normbeg rcontloop7,7
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normalbeg2dc6:
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normbeg rcontloop6,6
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normalbeg2dc5:
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normbeg rcontloop5,5
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normalbeg2dc4:
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normbeg rcontloop4,4
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normalbeg2dc3:
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normbeg rcontloop3,3
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normalbeg2dc2:
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normbeg rcontloop2,2
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normalbeg2dc1:
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normbeg rcontloop1,1
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normalbeg2dc0:
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normbeg rcontloop0,0
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; we go in normalbeg2 because *(ushf*)(match+best_len-1) == scan_end
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normalbeg2:
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mov edi,window
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cmp bp,word ptr[edi+eax]
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jne contloop3 ; if *(ushf*)match != scan_start, continue
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iseq:
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; if we are here, we know that *(match+best_len-1) == scan_end
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; and (match == scan_start)
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mov edi,edx
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mov esi,scan ; esi = scan
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add edi,eax ; edi = window + cur_match = match
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mov edx,[esi+3] ; compare manually dword at match+3
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xor edx,[edi+3] ; and scan +3
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jz begincompare ; if equal, go to long compare
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; we will determine the unmatch byte and calculate len (in esi)
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or dl,dl
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je eq1rr
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mov esi,3
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jmp trfinval
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eq1rr:
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or dx,dx
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je eq1
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mov esi,4
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jmp trfinval
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eq1:
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and edx,0ffffffh
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jz eq11
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mov esi,5
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jmp trfinval
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eq11:
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mov esi,6
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jmp trfinval
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begincompare:
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; here we now scan and match begin same
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add edi,6
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add esi,6
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mov ecx,(MAX_MATCH-(2+4))/4 ; scan for at most MAX_MATCH bytes
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repe cmpsd ; loop until mismatch
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je trfin ; go to trfin if not unmatch
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; we determine the unmatch byte
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sub esi,4
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mov edx,[edi-4]
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xor edx,[esi]
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or dl,dl
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jnz trfin
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inc esi
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or dx,dx
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jnz trfin
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inc esi
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and edx,0ffffffh
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jnz trfin
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inc esi
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trfin:
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sub esi,scan ; esi = len
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trfinval:
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; here we have finised compare, and esi contain len of equal string
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cmp esi,best_len ; if len > best_len, go newbestlen
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ja short newbestlen
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; now we restore edx, ecx and esi, for the big loop
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mov esi,prev
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mov ecx,limit
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mov edx,window
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jmp contloop3
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newbestlen:
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mov best_len,esi ; len become best_len
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mov match_start,eax ; save new position as match_start
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cmp esi,nice_match ; if best_len >= nice_match, exit
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jae exitloop
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mov ecx,scan
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mov edx,window ; restore edx=window
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add ecx,esi
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add esi,edx
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dec esi
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mov windowlen,esi ; windowlen = window + best_len-1
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mov bx,[ecx-1] ; bx = *(scan+best_len-1) = scan_end
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; now we restore ecx and esi, for the big loop :
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mov esi,prev
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mov ecx,limit
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jmp contloop3
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exitloop:
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; exit : s->match_start=match_start
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mov ebx,match_start
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mov ebp,str_s
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mov ecx,best_len
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mov dword ptr [ebp+dep_match_start],ebx
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mov eax,dword ptr [ebp+dep_lookahead]
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cmp ecx,eax
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ja minexlo
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mov eax,ecx
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minexlo:
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; return min(best_len,s->lookahead)
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|
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; restore stack and register ebx,esi,edi,ebp
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||
add esp,NbStackAdd
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pop ebx
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pop esi
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pop edi
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||
pop ebp
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ret
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||
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
|
||
|
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|
||
|
||
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<61>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<61>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
|