;uInt longest_match_x64(
; deflate_state *s,
; IPos cur_match); /* current match */
; gvmat64.asm -- Asm portion of the optimized longest_match for 32 bits x86
; Copyright (C) 1995-2005 Jean-loup Gailly, Brian Raiter and Gilles Vollant.
;
; File written by Gilles Vollant, by converting to assembly the longest_match
; from Jean-loup Gailly in deflate.c of zLib and infoZip zip.
;
; and by taking inspiration on asm686 with masm, optimised assembly code
; from Brian Raiter, written 1998
;
; http://www.zlib.net
; http://www.winimage.com/zLibDll
; http://www.muppetlabs.com/~breadbox/software/assembly.html
;
; to compile this file for infozip Zip, I use option:
; ml64.exe /Flgvmat64 /c /Zi /DINFOZIP gvmat64.asm
;
; to compile this file for zLib, I use option:
; ml64.exe /Flgvmat64 /c /Zi gvmat64.asm
; Be carrefull to adapt zlib1222add below to your version of zLib
; (if you use a version of zLib before 1.0.4 or after 1.2.2.2, change
; value of zlib1222add later)
;
; This file compile with Microsoft Macro Assembler (x64) for AMD64
;
; ml64.exe is given with Visual Studio 2005 and Windows 2003 server DDK
;
; (you can get Windows 2003 server DDK with ml64 and cl for AMD64 from
; http://www.microsoft.com/whdc/devtools/ddk/default.mspx for low price)
;
;uInt longest_match(s, cur_match)
; deflate_state *s;
; IPos cur_match; /* current match */
.code
longest_match PROC
;LocalVarsSize equ 88
LocalVarsSize equ 72
; register used : rax,rbx,rcx,rdx,rsi,rdi,r8,r9,r10,r11,r12
; free register : r14,r15
; register can be saved : rsp
chainlenwmask equ rsp + 8 - LocalVarsSize ; high word: current chain len
; low word: s->wmask
;window equ rsp + xx - LocalVarsSize ; local copy of s->window ; stored in r10
;windowbestlen equ rsp + xx - LocalVarsSize ; s->window + bestlen , use r10+r11
;scanstart equ rsp + xx - LocalVarsSize ; first two bytes of string ; stored in r12w
;scanend equ rsp + xx - LocalVarsSize ; last two bytes of string use ebx
;scanalign equ rsp + xx - LocalVarsSize ; dword-misalignment of string r13
;bestlen equ rsp + xx - LocalVarsSize ; size of best match so far -> r11d
;scan equ rsp + xx - LocalVarsSize ; ptr to string wanting match -> r9
IFDEF INFOZIP
ELSE
nicematch equ (rsp + 16 - LocalVarsSize) ; a good enough match size
ENDIF
save_rdi equ rsp + 24 - LocalVarsSize
save_rsi equ rsp + 32 - LocalVarsSize
save_rbx equ rsp + 40 - LocalVarsSize
save_rbp equ rsp + 48 - LocalVarsSize
save_r12 equ rsp + 56 - LocalVarsSize
save_r13 equ rsp + 64 - LocalVarsSize
;save_r14 equ rsp + 72 - LocalVarsSize
;save_r15 equ rsp + 80 - LocalVarsSize
; all the +4 offsets are due to the addition of pending_buf_size (in zlib
; in the deflate_state structure since the asm code was first written
; (if you compile with zlib 1.0.4 or older, remove the +4).
; Note : these value are good with a 8 bytes boundary pack structure
MAX_MATCH equ 258
MIN_MATCH equ 3
MIN_LOOKAHEAD equ (MAX_MATCH+MIN_MATCH+1)
;;; 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.)
; 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").
IFDEF INFOZIP
_DATA SEGMENT
COMM window_size:DWORD
; WMask ; 7fff
COMM window:BYTE:010040H
COMM prev:WORD:08000H
; MatchLen : unused
; PrevMatch : unused
COMM strstart:DWORD
COMM match_start:DWORD
; Lookahead : ignore
COMM prev_length:DWORD ; PrevLen
COMM max_chain_length:DWORD
COMM good_match:DWORD
COMM nice_match:DWORD
prev_ad equ OFFSET prev
window_ad equ OFFSET window
nicematch equ nice_match
_DATA ENDS
WMask equ 07fffh
ELSE
IFNDEF zlib1222add
zlib1222add equ 8
ENDIF
dsWSize equ 56+zlib1222add+(zlib1222add/2)
dsWMask equ 64+zlib1222add+(zlib1222add/2)
dsWindow equ 72+zlib1222add
dsPrev equ 88+zlib1222add
dsMatchLen equ 128+zlib1222add
dsPrevMatch equ 132+zlib1222add
dsStrStart equ 140+zlib1222add
dsMatchStart equ 144+zlib1222add
dsLookahead equ 148+zlib1222add
dsPrevLen equ 152+zlib1222add
dsMaxChainLen equ 156+zlib1222add
dsGoodMatch equ 172+zlib1222add
dsNiceMatch equ 176+zlib1222add
window_size equ [ rcx + dsWSize]
WMask equ [ rcx + dsWMask]
window_ad equ [ rcx + dsWindow]
prev_ad equ [ rcx + dsPrev]
strstart equ [ rcx + dsStrStart]
match_start equ [ rcx + dsMatchStart]
Lookahead equ [ rcx + dsLookahead] ; 0ffffffffh on infozip
prev_length equ [ rcx + dsPrevLen]
max_chain_length equ [ rcx + dsMaxChainLen]
good_match equ [ rcx + dsGoodMatch]
nice_match equ [ rcx + dsNiceMatch]
ENDIF
; parameter 1 in r8(deflate state s), param 2 in rdx (cur match)
; see http://weblogs.asp.net/oldnewthing/archive/2004/01/14/58579.aspx and
; http://msdn.microsoft.com/library/en-us/kmarch/hh/kmarch/64bitAMD_8e951dd2-ee77-4728-8702-55ce4b5dd24a.xml.asp
;
; All registers must be preserved across the call, except for
; rax, rcx, rdx, r8, r9, r10, and r11, which are scratch.
;;; Save registers that the compiler may be using, and adjust esp to
;;; make room for our stack frame.
;;; Retrieve the function arguments. r8d 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.
; parameter 1 in rcx (deflate_state* s), param 2 in edx -> r8 (cur match)
; this clear high 32 bits of r8, which can be garbage in both r8 and rdx
mov [save_rdi],rdi
mov [save_rsi],rsi
mov [save_rbx],rbx
mov [save_rbp],rbp
IFDEF INFOZIP
mov r8d,ecx
ELSE
mov r8d,edx
ENDIF
mov [save_r12],r12
mov [save_r13],r13
; mov [save_r14],r14
; mov [save_r15],r15
;;; uInt wmask = s->w_mask;
;;; unsigned chain_length = s->max_chain_length;
;;; if (s->prev_length >= s->good_match) {
;;; chain_length >>= 2;
;;; }
mov edi, prev_length
mov esi, good_match
mov eax, WMask
mov ebx, max_chain_length
cmp edi, esi
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
;;; on zlib only
;;; if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
IFDEF INFOZIP
mov [chainlenwmask], ebx
; on infozip nice_match = [nice_match]
ELSE
mov eax, nice_match
mov [chainlenwmask], ebx
mov r10d, Lookahead
cmp r10d, eax
cmovnl r10d, eax
mov [nicematch],r10d
ENDIF
;;; register Bytef *scan = s->window + s->strstart;
mov r10, window_ad
mov ebp, strstart
lea r13, [r10 + rbp]
;;; Determine how many bytes the scan ptr is off from being
;;; dword-aligned.
mov r9,r13
neg r13
and r13,3
;;; IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
;;; s->strstart - (IPos)MAX_DIST(s) : NIL;
IFDEF INFOZIP
mov eax,07efah ; MAX_DIST = (WSIZE-MIN_LOOKAHEAD) (0x8000-(3+8+1))
ELSE
mov eax, window_size
sub eax, MIN_LOOKAHEAD
ENDIF
xor edi,edi
sub ebp, eax
mov r11d, prev_length
cmovng ebp,edi
;;; int best_len = s->prev_length;
;;; Store the sum of s->window + best_len in esi locally, and in esi.
lea rsi,[r10+r11]
;;; register ush scan_start = *(ushf*)scan;
;;; register ush scan_end = *(ushf*)(scan+best_len-1);
;;; Posf *prev = s->prev;
movzx r12d,word ptr [r9]
movzx ebx, word ptr [r9 + r11 - 1]
mov rdi, prev_ad
;;; Jump into the main loop.
mov edx, [chainlenwmask]
cmp bx,word ptr [rsi + r8 - 1]
jz LookupLoopIsZero
LookupLoop1:
and r8d, edx
movzx r8d, word ptr [rdi + r8*2]
cmp r8d, ebp
jbe LeaveNow
sub edx, 00010000h
js LeaveNow
LoopEntry1:
cmp bx,word ptr [rsi + r8 - 1]
jz LookupLoopIsZero
LookupLoop2:
and r8d, edx
movzx r8d, word ptr [rdi + r8*2]
cmp r8d, ebp
jbe LeaveNow
sub edx, 00010000h
js LeaveNow
LoopEntry2:
cmp bx,word ptr [rsi + r8 - 1]
jz LookupLoopIsZero
LookupLoop4:
and r8d, edx
movzx r8d, word ptr [rdi + r8*2]
cmp r8d, ebp
jbe LeaveNow
sub edx, 00010000h
js LeaveNow
LoopEntry4:
cmp bx,word ptr [rsi + r8 - 1]
jnz LookupLoop1
jmp LookupLoopIsZero
;;; 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
;;; r8d = curmatch
;;; edx = chainlenwmask - i.e., ((chainlen << 16) | wmask)
;;; esi = windowbestlen - i.e., (window + bestlen)
;;; edi = prev
;;; ebp = limit
LookupLoop:
and r8d, edx
movzx r8d, word ptr [rdi + r8*2]
cmp r8d, ebp
jbe LeaveNow
sub edx, 00010000h
js LeaveNow
LoopEntry:
cmp bx,word ptr [rsi + r8 - 1]
jnz LookupLoop1
LookupLoopIsZero:
cmp r12w, word ptr [r10 + r8]
jnz LookupLoop1
;;; 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).
lea rsi,[r8+r10]
mov rdx, 0fffffffffffffef8h; -(MAX_MATCH_8)
lea rsi, [rsi + r13 + 0108h] ;MAX_MATCH_8]
lea rdi, [r9 + r13 + 0108h] ;MAX_MATCH_8]
prefetcht1 [rsi+rdx]
prefetcht1 [rdi+rdx]
;;; Test the strings for equality, 8 bytes at a time. At the end,
;;; adjust rdx 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. (rsi 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 rax, [rsi + rdx]
xor rax, [rdi + rdx]
jnz LeaveLoopCmps
mov rax, [rsi + rdx + 8]
xor rax, [rdi + rdx + 8]
jnz LeaveLoopCmps8
mov rax, [rsi + rdx + 8+8]
xor rax, [rdi + rdx + 8+8]
jnz LeaveLoopCmps16
add rdx,8+8+8
jmp short LoopCmps
LeaveLoopCmps16: add rdx,8
LeaveLoopCmps8: add rdx,8
LeaveLoopCmps:
test eax, 0000FFFFh
jnz LenLower
test eax,0ffffffffh
jnz LenLower32
add rdx,4
shr rax,32
or ax,ax
jnz LenLower
LenLower32:
shr eax,16
add rdx,2
LenLower: sub al, 1
adc rdx, 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 rax, [rdi + rdx]
sub rax, r9
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.
;///////////////////////////////////
cmp eax, r11d
jg LongerMatch
lea rsi,[r10+r11]
mov rdi, prev_ad
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 r11d, eax
mov match_start, r8d
cmp eax, [nicematch]
jge LeaveNow
lea rsi,[r10+rax]
movzx ebx, word ptr [r9 + rax - 1]
mov rdi, prev_ad
mov edx, [chainlenwmask]
jmp LookupLoop
;;; Accept the current string, with the maximum possible length.
LenMaximum:
mov r11d,MAX_MATCH
mov match_start, r8d
;;; if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
;;; return s->lookahead;
LeaveNow:
IFDEF INFOZIP
mov eax,r11d
ELSE
mov eax, Lookahead
cmp r11d, eax
cmovng eax, r11d
ENDIF
;;; Restore the stack and return from whence we came.
mov rsi,[save_rsi]
mov rdi,[save_rdi]
mov rbx,[save_rbx]
mov rbp,[save_rbp]
mov r12,[save_r12]
mov r13,[save_r13]
; mov r14,[save_r14]
; mov r15,[save_r15]
ret 0
; please don't remove this string !
; Your can freely use gvmat64 in any free or commercial app
; but it is far better don't remove the string in the binary!
db 0dh,0ah,"asm686 with masm, optimised assembly code from Brian Raiter, written 1998, converted to amd 64 by Gilles Vollant 2005",0dh,0ah,0
longest_match ENDP
match_init PROC
ret 0
match_init ENDP
END