| /* |
| * match.S -- optimized version of longest_match() |
| * based on the similar work by Gilles Vollant, and Brian Raiter, written 1998 |
| * |
| * This is free software; you can redistribute it and/or modify it |
| * under the terms of the BSD License. Use by owners of Che Guevarra |
| * parafernalia is prohibited, where possible, and highly discouraged |
| * elsewhere. |
| */ |
| |
| #ifndef NO_UNDERLINE |
| # define match_init _match_init |
| # define longest_match _longest_match |
| #endif |
| |
| #define scanend ebx |
| #define scanendw bx |
| #define chainlenwmask edx /* high word: current chain len low word: s->wmask */ |
| #define curmatch rsi |
| #define curmatchd esi |
| #define windowbestlen r8 |
| #define scanalign r9 |
| #define scanalignd r9d |
| #define window r10 |
| #define bestlen r11 |
| #define bestlend r11d |
| #define scanstart r12d |
| #define scanstartw r12w |
| #define scan r13 |
| #define nicematch r14d |
| #define limit r15 |
| #define limitd r15d |
| #define prev rcx |
| |
| /* |
| * The 258 is a "magic number, not a parameter -- changing it |
| * breaks the hell loose |
| */ |
| #define MAX_MATCH (258) |
| #define MIN_MATCH (3) |
| #define MIN_LOOKAHEAD (MAX_MATCH + MIN_MATCH + 1) |
| #define MAX_MATCH_8 ((MAX_MATCH + 7) & ~7) |
| |
| /* stack frame offsets */ |
| #define LocalVarsSize (112) |
| #define _chainlenwmask ( 8-LocalVarsSize)(%rsp) |
| #define _windowbestlen (16-LocalVarsSize)(%rsp) |
| #define save_r14 (24-LocalVarsSize)(%rsp) |
| #define save_rsi (32-LocalVarsSize)(%rsp) |
| #define save_rbx (40-LocalVarsSize)(%rsp) |
| #define save_r12 (56-LocalVarsSize)(%rsp) |
| #define save_r13 (64-LocalVarsSize)(%rsp) |
| #define save_r15 (80-LocalVarsSize)(%rsp) |
| |
| |
| .globl match_init, longest_match |
| |
| /* |
| * On AMD64 the first argument of a function (in our case -- the pointer to |
| * deflate_state structure) is passed in %rdi, hence our offsets below are |
| * all off of that. |
| */ |
| |
| /* you can check the structure offset by running |
| |
| #include <stdlib.h> |
| #include <stdio.h> |
| #include "deflate.h" |
| |
| void print_depl() |
| { |
| deflate_state ds; |
| deflate_state *s=&ds; |
| printf("size pointer=%u\n",(int)sizeof(void*)); |
| |
| printf("#define dsWSize (%3u)(%%rdi)\n",(int)(((char*)&(s->w_size))-((char*)s))); |
| printf("#define dsWMask (%3u)(%%rdi)\n",(int)(((char*)&(s->w_mask))-((char*)s))); |
| printf("#define dsWindow (%3u)(%%rdi)\n",(int)(((char*)&(s->window))-((char*)s))); |
| printf("#define dsPrev (%3u)(%%rdi)\n",(int)(((char*)&(s->prev))-((char*)s))); |
| printf("#define dsMatchLen (%3u)(%%rdi)\n",(int)(((char*)&(s->match_length))-((char*)s))); |
| printf("#define dsPrevMatch (%3u)(%%rdi)\n",(int)(((char*)&(s->prev_match))-((char*)s))); |
| printf("#define dsStrStart (%3u)(%%rdi)\n",(int)(((char*)&(s->strstart))-((char*)s))); |
| printf("#define dsMatchStart (%3u)(%%rdi)\n",(int)(((char*)&(s->match_start))-((char*)s))); |
| printf("#define dsLookahead (%3u)(%%rdi)\n",(int)(((char*)&(s->lookahead))-((char*)s))); |
| printf("#define dsPrevLen (%3u)(%%rdi)\n",(int)(((char*)&(s->prev_length))-((char*)s))); |
| printf("#define dsMaxChainLen (%3u)(%%rdi)\n",(int)(((char*)&(s->max_chain_length))-((char*)s))); |
| printf("#define dsGoodMatch (%3u)(%%rdi)\n",(int)(((char*)&(s->good_match))-((char*)s))); |
| printf("#define dsNiceMatch (%3u)(%%rdi)\n",(int)(((char*)&(s->nice_match))-((char*)s))); |
| } |
| |
| */ |
| |
| |
| /* |
| to compile for XCode 3.2 on MacOSX x86_64 |
| - run "gcc -g -c -DXCODE_MAC_X64_STRUCTURE amd64-match.S" |
| */ |
| |
| |
| #ifndef CURRENT_LINX_XCODE_MAC_X64_STRUCTURE |
| #define dsWSize ( 68)(%rdi) |
| #define dsWMask ( 76)(%rdi) |
| #define dsWindow ( 80)(%rdi) |
| #define dsPrev ( 96)(%rdi) |
| #define dsMatchLen (144)(%rdi) |
| #define dsPrevMatch (148)(%rdi) |
| #define dsStrStart (156)(%rdi) |
| #define dsMatchStart (160)(%rdi) |
| #define dsLookahead (164)(%rdi) |
| #define dsPrevLen (168)(%rdi) |
| #define dsMaxChainLen (172)(%rdi) |
| #define dsGoodMatch (188)(%rdi) |
| #define dsNiceMatch (192)(%rdi) |
| |
| #else |
| |
| #ifndef STRUCT_OFFSET |
| # define STRUCT_OFFSET (0) |
| #endif |
| |
| |
| #define dsWSize ( 56 + STRUCT_OFFSET)(%rdi) |
| #define dsWMask ( 64 + STRUCT_OFFSET)(%rdi) |
| #define dsWindow ( 72 + STRUCT_OFFSET)(%rdi) |
| #define dsPrev ( 88 + STRUCT_OFFSET)(%rdi) |
| #define dsMatchLen (136 + STRUCT_OFFSET)(%rdi) |
| #define dsPrevMatch (140 + STRUCT_OFFSET)(%rdi) |
| #define dsStrStart (148 + STRUCT_OFFSET)(%rdi) |
| #define dsMatchStart (152 + STRUCT_OFFSET)(%rdi) |
| #define dsLookahead (156 + STRUCT_OFFSET)(%rdi) |
| #define dsPrevLen (160 + STRUCT_OFFSET)(%rdi) |
| #define dsMaxChainLen (164 + STRUCT_OFFSET)(%rdi) |
| #define dsGoodMatch (180 + STRUCT_OFFSET)(%rdi) |
| #define dsNiceMatch (184 + STRUCT_OFFSET)(%rdi) |
| |
| #endif |
| |
| |
| |
| |
| .text |
| |
| /* uInt longest_match(deflate_state *deflatestate, IPos curmatch) */ |
| |
| longest_match: |
| /* |
| * Retrieve the function arguments. %curmatch will hold cur_match |
| * throughout the entire function (passed via rsi on amd64). |
| * rdi will hold the pointer to the deflate_state (first arg on amd64) |
| */ |
| mov %rsi, save_rsi |
| mov %rbx, save_rbx |
| mov %r12, save_r12 |
| mov %r13, save_r13 |
| mov %r14, save_r14 |
| mov %r15, save_r15 |
| |
| /* uInt wmask = s->w_mask; */ |
| /* unsigned chain_length = s->max_chain_length; */ |
| /* if (s->prev_length >= s->good_match) { */ |
| /* chain_length >>= 2; */ |
| /* } */ |
| |
| movl dsPrevLen, %eax |
| movl dsGoodMatch, %ebx |
| cmpl %ebx, %eax |
| movl dsWMask, %eax |
| movl dsMaxChainLen, %chainlenwmask |
| jl LastMatchGood |
| shrl $2, %chainlenwmask |
| 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. */ |
| |
| decl %chainlenwmask |
| shll $16, %chainlenwmask |
| orl %eax, %chainlenwmask |
| |
| /* if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead; */ |
| |
| movl dsNiceMatch, %eax |
| movl dsLookahead, %ebx |
| cmpl %eax, %ebx |
| jl LookaheadLess |
| movl %eax, %ebx |
| LookaheadLess: movl %ebx, %nicematch |
| |
| /* register Bytef *scan = s->window + s->strstart; */ |
| |
| mov dsWindow, %window |
| movl dsStrStart, %limitd |
| lea (%limit, %window), %scan |
| |
| /* Determine how many bytes the scan ptr is off from being */ |
| /* dword-aligned. */ |
| |
| mov %scan, %scanalign |
| negl %scanalignd |
| andl $3, %scanalignd |
| |
| /* IPos limit = s->strstart > (IPos)MAX_DIST(s) ? */ |
| /* s->strstart - (IPos)MAX_DIST(s) : NIL; */ |
| |
| movl dsWSize, %eax |
| subl $MIN_LOOKAHEAD, %eax |
| xorl %ecx, %ecx |
| subl %eax, %limitd |
| cmovng %ecx, %limitd |
| |
| /* int best_len = s->prev_length; */ |
| |
| movl dsPrevLen, %bestlend |
| |
| /* Store the sum of s->window + best_len in %windowbestlen locally, and in memory. */ |
| |
| lea (%window, %bestlen), %windowbestlen |
| mov %windowbestlen, _windowbestlen |
| |
| /* register ush scan_start = *(ushf*)scan; */ |
| /* register ush scan_end = *(ushf*)(scan+best_len-1); */ |
| /* Posf *prev = s->prev; */ |
| |
| movzwl (%scan), %scanstart |
| movzwl -1(%scan, %bestlen), %scanend |
| mov dsPrev, %prev |
| |
| /* Jump into the main loop. */ |
| |
| movl %chainlenwmask, _chainlenwmask |
| jmp LoopEntry |
| |
| .balign 16 |
| |
| /* 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. |
| */ |
| LookupLoop: |
| andl %chainlenwmask, %curmatchd |
| movzwl (%prev, %curmatch, 2), %curmatchd |
| cmpl %limitd, %curmatchd |
| jbe LeaveNow |
| subl $0x00010000, %chainlenwmask |
| js LeaveNow |
| LoopEntry: cmpw -1(%windowbestlen, %curmatch), %scanendw |
| jne LookupLoop |
| cmpw %scanstartw, (%window, %curmatch) |
| jne LookupLoop |
| |
| /* Store the current value of chainlen. */ |
| movl %chainlenwmask, _chainlenwmask |
| |
| /* %scan is the string under scrutiny, and %prev 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 $(-MAX_MATCH_8), %rdx |
| lea (%curmatch, %window), %windowbestlen |
| lea MAX_MATCH_8(%windowbestlen, %scanalign), %windowbestlen |
| lea MAX_MATCH_8(%scan, %scanalign), %prev |
| |
| /* the prefetching below makes very little difference... */ |
| prefetcht1 (%windowbestlen, %rdx) |
| prefetcht1 (%prev, %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. |
| * |
| * 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 -- unrolling it, for example, makes no difference. |
| */ |
| |
| #undef USE_SSE /* works, but is 6-7% slower, than non-SSE... */ |
| |
| LoopCmps: |
| #ifdef USE_SSE |
| /* Preload the SSE registers */ |
| movdqu (%windowbestlen, %rdx), %xmm1 |
| movdqu (%prev, %rdx), %xmm2 |
| pcmpeqb %xmm2, %xmm1 |
| movdqu 16(%windowbestlen, %rdx), %xmm3 |
| movdqu 16(%prev, %rdx), %xmm4 |
| pcmpeqb %xmm4, %xmm3 |
| movdqu 32(%windowbestlen, %rdx), %xmm5 |
| movdqu 32(%prev, %rdx), %xmm6 |
| pcmpeqb %xmm6, %xmm5 |
| movdqu 48(%windowbestlen, %rdx), %xmm7 |
| movdqu 48(%prev, %rdx), %xmm8 |
| pcmpeqb %xmm8, %xmm7 |
| |
| /* Check the comparisions' results */ |
| pmovmskb %xmm1, %rax |
| notw %ax |
| bsfw %ax, %ax |
| jnz LeaveLoopCmps |
| |
| /* this is the only iteration of the loop with a possibility of having |
| incremented rdx by 0x108 (each loop iteration add 16*4 = 0x40 |
| and (0x40*4)+8=0x108 */ |
| add $8, %rdx |
| jz LenMaximum |
| add $8, %rdx |
| |
| |
| pmovmskb %xmm3, %rax |
| notw %ax |
| bsfw %ax, %ax |
| jnz LeaveLoopCmps |
| |
| |
| add $16, %rdx |
| |
| |
| pmovmskb %xmm5, %rax |
| notw %ax |
| bsfw %ax, %ax |
| jnz LeaveLoopCmps |
| |
| add $16, %rdx |
| |
| |
| pmovmskb %xmm7, %rax |
| notw %ax |
| bsfw %ax, %ax |
| jnz LeaveLoopCmps |
| |
| add $16, %rdx |
| |
| jmp LoopCmps |
| LeaveLoopCmps: add %rax, %rdx |
| #else |
| mov (%windowbestlen, %rdx), %rax |
| xor (%prev, %rdx), %rax |
| jnz LeaveLoopCmps |
| |
| mov 8(%windowbestlen, %rdx), %rax |
| xor 8(%prev, %rdx), %rax |
| jnz LeaveLoopCmps8 |
| |
| mov 16(%windowbestlen, %rdx), %rax |
| xor 16(%prev, %rdx), %rax |
| jnz LeaveLoopCmps16 |
| |
| add $24, %rdx |
| jnz LoopCmps |
| jmp LenMaximum |
| # if 0 |
| /* |
| * This three-liner is tantalizingly simple, but bsf is a slow instruction, |
| * and the complicated alternative down below is quite a bit faster. Sad... |
| */ |
| |
| LeaveLoopCmps: bsf %rax, %rax /* find the first non-zero bit */ |
| shrl $3, %eax /* divide by 8 to get the byte */ |
| add %rax, %rdx |
| # else |
| LeaveLoopCmps16: |
| add $8, %rdx |
| LeaveLoopCmps8: |
| add $8, %rdx |
| LeaveLoopCmps: testl $0xFFFFFFFF, %eax /* Check the first 4 bytes */ |
| jnz Check16 |
| add $4, %rdx |
| shr $32, %rax |
| Check16: testw $0xFFFF, %ax |
| jnz LenLower |
| add $2, %rdx |
| shrl $16, %eax |
| LenLower: subb $1, %al |
| adc $0, %rdx |
| # endif |
| #endif |
| |
| /* 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 (%prev, %rdx), %rax |
| sub %scan, %rax |
| cmpl $MAX_MATCH, %eax |
| 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. */ |
| |
| cmpl %bestlend, %eax |
| jg LongerMatch |
| mov _windowbestlen, %windowbestlen |
| mov dsPrev, %prev |
| movl _chainlenwmask, %edx |
| jmp LookupLoop |
| |
| /* s->match_start = cur_match; */ |
| /* best_len = len; */ |
| /* if (len >= nice_match) break; */ |
| /* scan_end = *(ushf*)(scan+best_len-1); */ |
| |
| LongerMatch: |
| movl %eax, %bestlend |
| movl %curmatchd, dsMatchStart |
| cmpl %nicematch, %eax |
| jge LeaveNow |
| |
| lea (%window, %bestlen), %windowbestlen |
| mov %windowbestlen, _windowbestlen |
| |
| movzwl -1(%scan, %rax), %scanend |
| mov dsPrev, %prev |
| movl _chainlenwmask, %chainlenwmask |
| jmp LookupLoop |
| |
| /* Accept the current string, with the maximum possible length. */ |
| |
| LenMaximum: |
| movl $MAX_MATCH, %bestlend |
| movl %curmatchd, dsMatchStart |
| |
| /* if ((uInt)best_len <= s->lookahead) return (uInt)best_len; */ |
| /* return s->lookahead; */ |
| |
| LeaveNow: |
| movl dsLookahead, %eax |
| cmpl %eax, %bestlend |
| cmovngl %bestlend, %eax |
| LookaheadRet: |
| |
| /* Restore the registers and return from whence we came. */ |
| |
| mov save_rsi, %rsi |
| mov save_rbx, %rbx |
| mov save_r12, %r12 |
| mov save_r13, %r13 |
| mov save_r14, %r14 |
| mov save_r15, %r15 |
| |
| ret |
| |
| match_init: ret |