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match.S
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/* match.s -- optional optimized asm version of longest match in deflate.c
* Copyright (C) 1992-1993 Jean-loup Gailly
* This is free software; you can redistribute it and/or modify it under the
* terms of the GNU General Public License, see the file COPYING.
*
* The 68020 version has been written by Francesco Potorti` <[email protected]>
* with adaptations by Carsten Steger <[email protected]>,
* Andreas Schwab <[email protected]> and
* Kristoffer Eriksson <[email protected]>
*/
/* $Id: match.S,v 0.14 1993/06/11 18:33:24 jloup Exp $ */
/* Preprocess with -DNO_UNDERLINE if your C compiler does not prefix
* external symbols with an underline character '_'.
*/
#ifdef NO_UNDERLINE
# define _prev prev
# define _window window
# define _match_start match_start
# define _prev_length prev_length
# define _good_match good_match
# define _nice_match nice_match
# define _strstart strstart
# define _max_chain_length max_chain_length
# define _match_init match_init
# define _longest_match longest_match
#endif
#ifdef DYN_ALLOC
error: DYN_ALLOC not yet supported in match.s
#endif
#if defined(i386) || defined(_I386)
/* This version is for 386 Unix or OS/2 in 32 bit mode.
* Warning: it uses the AT&T syntax: mov source,dest
* This file is only optional. If you want to force the C version,
* add -DNO_ASM to CFLAGS in Makefile and set OBJA to an empty string.
* If you have reduced WSIZE in gzip.h, then change its value below.
* This version assumes static allocation of the arrays (-DDYN_ALLOC not used).
*/
.file "match.S"
#define MAX_MATCH 258
#define MAX_MATCH2 $128 /* MAX_MATCH/2-1 */
#define MIN_MATCH 3
#define WSIZE $32768
#define MAX_DIST WSIZE - MAX_MATCH - MIN_MATCH - 1
.globl _match_init
.globl _longest_match
.text
_match_init:
ret
/*-----------------------------------------------------------------------
* Set match_start to the longest match starting at the given string and
* return its length. Matches shorter or equal to prev_length are discarded,
* in which case the result is equal to prev_length and match_start is
* garbage.
* IN assertions: cur_match is the head of the hash chain for the current
* string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
*/
_longest_match: /* int longest_match(cur_match) */
#define cur_match 20(%esp)
/* return address */ /* esp+16 */
push %ebp /* esp+12 */
push %edi /* esp+8 */
push %esi /* esp+4 */
push %ebx /* esp */
/*
* match equ esi
* scan equ edi
* chain_length equ ebp
* best_len equ ebx
* limit equ edx
*/
mov cur_match,%esi
mov _max_chain_length,%ebp /* chain_length = max_chain_length */
mov _strstart,%edi
mov %edi,%edx
sub MAX_DIST,%edx /* limit = strstart-MAX_DIST */
jae limit_ok
sub %edx,%edx /* limit = NIL */
limit_ok:
add $2+_window,%edi /* edi = offset(window+strstart+2) */
mov _prev_length,%ebx /* best_len = prev_length */
movw -3(%ebx,%edi),%ax /* ax = scan[best_len-1..best_len] */
movw -2(%edi),%cx /* cx = scan[0..1] */
cmp _good_match,%ebx /* do we have a good match already? */
jb do_scan
shr $2,%ebp /* chain_length >>= 2 */
jmp do_scan
.align 4
long_loop:
/* at this point, edi == scan+2, esi == cur_match */
movw -3(%ebx,%edi),%ax /* ax = scan[best_len-1..best_len] */
movw -2(%edi),%cx /* cx = scan[0..1] */
short_loop:
/*
* at this point, di == scan+2, si == cur_match,
* ax = scan[best_len-1..best_len] and cx = scan[0..1]
*/
and WSIZE-1, %esi
movw _prev(%esi,%esi),%si /* cur_match = prev[cur_match] */
/* top word of esi is still 0 */
cmp %edx,%esi /* cur_match <= limit ? */
jbe the_end
dec %ebp /* --chain_length */
jz the_end
do_scan:
cmpw _window-1(%ebx,%esi),%ax/* check match at best_len-1 */
jne short_loop
cmpw _window(%esi),%cx /* check min_match_length match */
jne short_loop
lea _window+2(%esi),%esi /* si = match */
mov %edi,%eax /* ax = scan+2 */
mov MAX_MATCH2,%ecx /* scan for at most MAX_MATCH bytes */
rep; cmpsw /* loop until mismatch */
je maxmatch /* match of length MAX_MATCH? */
mismatch:
movb -2(%edi),%cl /* mismatch on first or second byte? */
subb -2(%esi),%cl /* cl = 0 if first bytes equal */
xchg %edi,%eax /* edi = scan+2, eax = end of scan */
sub %edi,%eax /* eax = len */
sub %eax,%esi /* esi = cur_match + 2 + offset(window) */
sub $2+_window,%esi /* esi = cur_match */
subb $1,%cl /* set carry if cl == 0 (cannot use DEC) */
adc $0,%eax /* eax = carry ? len+1 : len */
cmp %ebx,%eax /* len > best_len ? */
jle long_loop
mov %esi,_match_start /* match_start = cur_match */
mov %eax,%ebx /* ebx = best_len = len */
cmp _nice_match,%eax /* len >= nice_match ? */
jl long_loop
the_end:
mov %ebx,%eax /* result = eax = best_len */
pop %ebx
pop %esi
pop %edi
pop %ebp
ret
maxmatch:
cmpsb
jmp mismatch
#else
/* ======================== 680x0 version ================================= */
#if defined(m68k)||defined(mc68k)||defined(__mc68000__)||defined(__MC68000__)
# ifndef mc68000
# define mc68000
# endif
#endif
#if defined(__mc68020__) || defined(__MC68020__) || defined(sysV68)
# ifndef mc68020
# define mc68020
# endif
#endif
#if defined(mc68020) || defined(mc68000)
#if (defined(mc68020) || defined(NeXT)) && !defined(UNALIGNED_OK)
# define UNALIGNED_OK
#endif
#ifdef sysV68 /* Try Motorola Delta style */
# define GLOBAL(symbol) global symbol
# define TEXT text
# define FILE(filename) file filename
# define invert_maybe(src,dst) dst,src
# define imm(data) &data
# define reg(register) %register
# define addl add.l
# define addql addq.l
# define blos blo.b
# define bhis bhi.b
# define bras bra.b
# define clrl clr.l
# define cmpmb cmpm.b
# define cmpw cmp.w
# define cmpl cmp.l
# define lslw lsl.w
# define lsrl lsr.l
# define movel move.l
# define movew move.w
# define moveb move.b
# define moveml movem.l
# define subl sub.l
# define subw sub.w
# define subql subq.l
# define IndBase(bd,An) (bd,An)
# define IndBaseNdxl(bd,An,Xn) (bd,An,Xn.l)
# define IndBaseNdxw(bd,An,Xn) (bd,An,Xn.w)
# define predec(An) -(An)
# define postinc(An) (An)+
#else /* default style (Sun 3, NeXT, Amiga, Atari) */
# define GLOBAL(symbol) .globl symbol
# define TEXT .text
# define FILE(filename) .even
# define invert_maybe(src,dst) src,dst
# if defined(sun) || defined(mc68k)
# define imm(data) #data
# else
# define imm(data) \#data
# endif
# define reg(register) register
# define blos bcss
# if defined(sun) || defined(mc68k)
# define movel movl
# define movew movw
# define moveb movb
# endif
# define IndBase(bd,An) An@(bd)
# define IndBaseNdxl(bd,An,Xn) An@(bd,Xn:l)
# define IndBaseNdxw(bd,An,Xn) An@(bd,Xn:w)
# define predec(An) An@-
# define postinc(An) An@+
#endif /* styles */
#define Best_Len reg(d0) /* unsigned */
#define Cur_Match reg(d1) /* Ipos */
#define Loop_Counter reg(d2) /* int */
#define Scan_Start reg(d3) /* unsigned short */
#define Scan_End reg(d4) /* unsigned short */
#define Limit reg(d5) /* IPos */
#define Chain_Length reg(d6) /* unsigned */
#define Scan_Test reg(d7)
#define Scan reg(a0) /* *uch */
#define Match reg(a1) /* *uch */
#define Prev_Address reg(a2) /* *Pos */
#define Scan_Ini reg(a3) /* *uch */
#define Match_Ini reg(a4) /* *uch */
#define Stack_Pointer reg(sp)
#define MAX_MATCH 258
#define MIN_MATCH 3
#define WSIZE 32768
#define MAX_DIST (WSIZE - MAX_MATCH - MIN_MATCH - 1)
GLOBAL (_match_init)
GLOBAL (_longest_match)
TEXT
FILE ("match.S")
_match_init:
rts
/*-----------------------------------------------------------------------
* Set match_start to the longest match starting at the given string and
* return its length. Matches shorter or equal to prev_length are discarded,
* in which case the result is equal to prev_length and match_start is
* garbage.
* IN assertions: cur_match is the head of the hash chain for the current
* string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
*/
/* int longest_match (cur_match) */
#ifdef UNALIGNED_OK
# define pushreg 15928 /* d2-d6/a2-a4 */
# define popreg 7292
#else
# define pushreg 16184 /* d2-d7/a2-a4 */
# define popreg 7420
#endif
_longest_match:
movel IndBase(4,Stack_Pointer),Cur_Match
moveml imm(pushreg),predec(Stack_Pointer)
movel _max_chain_length,Chain_Length
movel _prev_length,Best_Len
movel imm(_prev),Prev_Address
movel imm(_window+MIN_MATCH),Match_Ini
movel _strstart,Limit
movel Match_Ini,Scan_Ini
addl Limit,Scan_Ini
subw imm(MAX_DIST),Limit
bhis L__limit_ok
clrl Limit
L__limit_ok:
cmpl invert_maybe(_good_match,Best_Len)
blos L__length_ok
lsrl imm(2),Chain_Length
L__length_ok:
subql imm(1),Chain_Length
#ifdef UNALIGNED_OK
movew IndBase(-MIN_MATCH,Scan_Ini),Scan_Start
movew IndBaseNdxw(-MIN_MATCH-1,Scan_Ini,Best_Len),Scan_End
#else
moveb IndBase(-MIN_MATCH,Scan_Ini),Scan_Start
lslw imm(8),Scan_Start
moveb IndBase(-MIN_MATCH+1,Scan_Ini),Scan_Start
moveb IndBaseNdxw(-MIN_MATCH-1,Scan_Ini,Best_Len),Scan_End
lslw imm(8),Scan_End
moveb IndBaseNdxw(-MIN_MATCH,Scan_Ini,Best_Len),Scan_End
#endif
bras L__do_scan
L__long_loop:
#ifdef UNALIGNED_OK
movew IndBaseNdxw(-MIN_MATCH-1,Scan_Ini,Best_Len),Scan_End
#else
moveb IndBaseNdxw(-MIN_MATCH-1,Scan_Ini,Best_Len),Scan_End
lslw imm(8),Scan_End
moveb IndBaseNdxw(-MIN_MATCH,Scan_Ini,Best_Len),Scan_End
#endif
L__short_loop:
lslw imm(1),Cur_Match
movew IndBaseNdxl(0,Prev_Address,Cur_Match),Cur_Match
cmpw invert_maybe(Limit,Cur_Match)
dbls Chain_Length,L__do_scan
bras L__return
L__do_scan:
movel Match_Ini,Match
addl Cur_Match,Match
#ifdef UNALIGNED_OK
cmpw invert_maybe(IndBaseNdxw(-MIN_MATCH-1,Match,Best_Len),Scan_End)
bne L__short_loop
cmpw invert_maybe(IndBase(-MIN_MATCH,Match),Scan_Start)
bne L__short_loop
#else
moveb IndBaseNdxw(-MIN_MATCH-1,Match,Best_Len),Scan_Test
lslw imm(8),Scan_Test
moveb IndBaseNdxw(-MIN_MATCH,Match,Best_Len),Scan_Test
cmpw invert_maybe(Scan_Test,Scan_End)
bne L__short_loop
moveb IndBase(-MIN_MATCH,Match),Scan_Test
lslw imm(8),Scan_Test
moveb IndBase(-MIN_MATCH+1,Match),Scan_Test
cmpw invert_maybe(Scan_Test,Scan_Start)
bne L__short_loop
#endif
movew imm((MAX_MATCH-MIN_MATCH+1)-1),Loop_Counter
movel Scan_Ini,Scan
L__scan_loop:
cmpmb postinc(Match),postinc(Scan)
dbne Loop_Counter,L__scan_loop
subl Scan_Ini,Scan
addql imm(MIN_MATCH-1),Scan
cmpl invert_maybe(Best_Len,Scan)
bls L__short_loop
movel Scan,Best_Len
movel Cur_Match,_match_start
cmpl invert_maybe(_nice_match,Best_Len)
blos L__long_loop
L__return:
moveml postinc(Stack_Pointer),imm(popreg)
rts
#else
error: this asm version is for 386 or 680x0 only
#endif /* mc68000 || mc68020 */
#endif /* i386 || _I386 */