Squashed 'zlib/' content from commit cacf7f1

git-subtree-dir: zlib
git-subtree-split: cacf7f1d4e3d44d871b605da3b647f07d718623f

2 files changed, 408 insertions, 0 deletions

diff --git a/contrib/asm686/README.686 b/contrib/asm686/README.686
new file mode 100644
index 0000000..a0bf3be
--- /dev/null
+++ b/contrib/asm686/README.686
@@ -0,0 +1,51 @@
+This is a patched version of zlib, modified to use
+Pentium-Pro-optimized assembly code in the deflation algorithm. The
+files changed/added by this patch are:
+
+README.686
+match.S
+
+The speedup that this patch provides varies, depending on whether the
+compiler used to build the original version of zlib falls afoul of the
+PPro's speed traps. My own tests show a speedup of around 10-20% at
+the default compression level, and 20-30% using -9, against a version
+compiled using gcc 2.7.2.3. Your mileage may vary.
+
+Note that this code has been tailored for the PPro/PII in particular,
+and will not perform particuarly well on a Pentium.
+
+If you are using an assembler other than GNU as, you will have to
+translate match.S to use your assembler's syntax. (Have fun.)
+
+Brian Raiter
+breadbox@muppetlabs.com
+April, 1998
+
+
+Added for zlib 1.1.3:
+
+The patches come from
+http://www.muppetlabs.com/~breadbox/software/assembly.html
+
+To compile zlib with this asm file, copy match.S to the zlib directory
+then do:
+
+CFLAGS="-O3 -DASMV" ./configure
+make OBJA=match.o
+
+
+Update:
+
+I've been ignoring these assembly routines for years, believing that
+gcc's generated code had caught up with it sometime around gcc 2.95
+and the major rearchitecting of the Pentium 4. However, I recently
+learned that, despite what I believed, this code still has some life
+in it. On the Pentium 4 and AMD64 chips, it continues to run about 8%
+faster than the code produced by gcc 4.1.
+
+In acknowledgement of its continuing usefulness, I've altered the
+license to match that of the rest of zlib. Share and Enjoy!
+
+Brian Raiter
+breadbox@muppetlabs.com
+April, 2007
diff --git a/contrib/asm686/match.S b/contrib/asm686/match.S
new file mode 100644
index 0000000..fa42109
--- /dev/null
+++ b/contrib/asm686/match.S
@@ -0,0 +1,357 @@
+/* match.S -- x86 assembly version of the zlib longest_match() function.
+ * Optimized for the Intel 686 chips (PPro and later).
+ *
+ * Copyright (C) 1998, 2007 Brian Raiter <breadbox@muppetlabs.com>
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the author be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ */
+
+#ifndef NO_UNDERLINE
+#define	match_init	_match_init
+#define	longest_match	_longest_match
+#endif
+
+#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	chainlenwmask		0	/* high word: current chain len	*/
+					/* low word: s->wmask		*/
+#define	window			4	/* local copy of s->window	*/
+#define	windowbestlen		8	/* s->window + bestlen		*/
+#define	scanstart		16	/* first two bytes of string	*/
+#define	scanend			12	/* last two bytes of string	*/
+#define	scanalign		20	/* dword-misalignment of string	*/
+#define	nicematch		24	/* a good enough match size	*/
+#define	bestlen			28	/* size of best match so far	*/
+#define	scan			32	/* ptr to string wanting match	*/
+
+#define	LocalVarsSize		(36)
+/*	saved ebx		36 */
+/*	saved edi		40 */
+/*	saved esi		44 */
+/*	saved ebp		48 */
+/*	return address		52 */
+#define	deflatestate		56	/* the function arguments	*/
+#define	curmatch		60
+
+/* 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").
+ */
+
+#define zlib1222add		(8)
+
+#define	dsWSize			(36+zlib1222add)
+#define	dsWMask			(44+zlib1222add)
+#define	dsWindow		(48+zlib1222add)
+#define	dsPrev			(56+zlib1222add)
+#define	dsMatchLen		(88+zlib1222add)
+#define	dsPrevMatch		(92+zlib1222add)
+#define	dsStrStart		(100+zlib1222add)
+#define	dsMatchStart		(104+zlib1222add)
+#define	dsLookahead		(108+zlib1222add)
+#define	dsPrevLen		(112+zlib1222add)
+#define	dsMaxChainLen		(116+zlib1222add)
+#define	dsGoodMatch		(132+zlib1222add)
+#define	dsNiceMatch		(136+zlib1222add)
+
+
+.file "match.S"
+
+.globl	match_init, longest_match
+
+.text
+
+/* uInt longest_match(deflate_state *deflatestate, IPos curmatch) */
+.cfi_sections	.debug_frame
+
+longest_match:
+
+.cfi_startproc
+/* Save registers that the compiler may be using, and adjust %esp to	*/
+/* make room for our stack frame.					*/
+
+		pushl	%ebp
+		.cfi_def_cfa_offset 8
+		.cfi_offset ebp, -8
+		pushl	%edi
+		.cfi_def_cfa_offset 12
+		pushl	%esi
+		.cfi_def_cfa_offset 16
+		pushl	%ebx
+		.cfi_def_cfa_offset 20
+		subl	$LocalVarsSize, %esp
+		.cfi_def_cfa_offset LocalVarsSize+20
+
+/* 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).						*/
+
+		movl	deflatestate(%esp), %edx
+		movl	curmatch(%esp), %ecx
+
+/* uInt wmask = s->w_mask;						*/
+/* unsigned chain_length = s->max_chain_length;				*/
+/* if (s->prev_length >= s->good_match) {				*/
+/*     chain_length >>= 2;						*/
+/* }									*/
+ 
+		movl	dsPrevLen(%edx), %eax
+		movl	dsGoodMatch(%edx), %ebx
+		cmpl	%ebx, %eax
+		movl	dsWMask(%edx), %eax
+		movl	dsMaxChainLen(%edx), %ebx
+		jl	LastMatchGood
+		shrl	$2, %ebx
+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	%ebx
+		shll	$16, %ebx
+		orl	%eax, %ebx
+		movl	%ebx, chainlenwmask(%esp)
+
+/* if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;	*/
+
+		movl	dsNiceMatch(%edx), %eax
+		movl	dsLookahead(%edx), %ebx
+		cmpl	%eax, %ebx
+		jl	LookaheadLess
+		movl	%eax, %ebx
+LookaheadLess:	movl	%ebx, nicematch(%esp)
+
+/* register Bytef *scan = s->window + s->strstart;			*/
+
+		movl	dsWindow(%edx), %esi
+		movl	%esi, window(%esp)
+		movl	dsStrStart(%edx), %ebp
+		lea	(%esi,%ebp), %edi
+		movl	%edi, scan(%esp)
+
+/* Determine how many bytes the scan ptr is off from being		*/
+/* dword-aligned.							*/
+
+		movl	%edi, %eax
+		negl	%eax
+		andl	$3, %eax
+		movl	%eax, scanalign(%esp)
+
+/* IPos limit = s->strstart > (IPos)MAX_DIST(s) ?			*/
+/*     s->strstart - (IPos)MAX_DIST(s) : NIL;				*/
+
+		movl	dsWSize(%edx), %eax
+		subl	$MIN_LOOKAHEAD, %eax
+		subl	%eax, %ebp
+		jg	LimitPositive
+		xorl	%ebp, %ebp
+LimitPositive:
+
+/* int best_len = s->prev_length;					*/
+
+		movl	dsPrevLen(%edx), %eax
+		movl	%eax, bestlen(%esp)
+
+/* Store the sum of s->window + best_len in %esi locally, and in %esi.	*/
+
+		addl	%eax, %esi
+		movl	%esi, windowbestlen(%esp)
+
+/* register ush scan_start = *(ushf*)scan;				*/
+/* register ush scan_end   = *(ushf*)(scan+best_len-1);			*/
+/* Posf *prev = s->prev;						*/
+
+		movzwl	(%edi), %ebx
+		movl	%ebx, scanstart(%esp)
+		movzwl	-1(%edi,%eax), %ebx
+		movl	%ebx, scanend(%esp)
+		movl	dsPrev(%edx), %edi
+
+/* Jump into the main loop.						*/
+
+		movl	chainlenwmask(%esp), %edx
+		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.
+ *
+ * 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:
+		andl	%edx, %ecx
+		movzwl	(%edi,%ecx,2), %ecx
+		cmpl	%ebp, %ecx
+		jbe	LeaveNow
+		subl	$0x00010000, %edx
+		js	LeaveNow
+LoopEntry:	movzwl	-1(%esi,%ecx), %eax
+		cmpl	%ebx, %eax
+		jnz	LookupLoop
+		movl	window(%esp), %eax
+		movzwl	(%eax,%ecx), %eax
+		cmpl	scanstart(%esp), %eax
+		jnz	LookupLoop
+
+/* Store the current value of chainlen.					*/
+
+		movl	%edx, chainlenwmask(%esp)
+
+/* 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).				*/
+
+		movl	window(%esp), %esi
+		movl	scan(%esp), %edi
+		addl	%ecx, %esi
+		movl	scanalign(%esp), %eax
+		movl	$(-MAX_MATCH_8), %edx
+		lea	MAX_MATCH_8(%edi,%eax), %edi
+		lea	MAX_MATCH_8(%esi,%eax), %esi
+
+/* 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:
+		movl	(%esi,%edx), %eax
+		xorl	(%edi,%edx), %eax
+		jnz	LeaveLoopCmps
+		movl	4(%esi,%edx), %eax
+		xorl	4(%edi,%edx), %eax
+		jnz	LeaveLoopCmps4
+		addl	$8, %edx
+		jnz	LoopCmps
+		jmp	LenMaximum
+LeaveLoopCmps4:	addl	$4, %edx
+LeaveLoopCmps:	testl	$0x0000FFFF, %eax
+		jnz	LenLower
+		addl	$2, %edx
+		shrl	$16, %eax
+LenLower:	subb	$1, %al
+		adcl	$0, %edx
+
+/* 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	(%edi,%edx), %eax
+		movl	scan(%esp), %edi
+		subl	%edi, %eax
+		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.		*/
+
+		movl	deflatestate(%esp), %edx
+		movl	bestlen(%esp), %ebx
+		cmpl	%ebx, %eax
+		jg	LongerMatch
+		movl	windowbestlen(%esp), %esi
+		movl	dsPrev(%edx), %edi
+		movl	scanend(%esp), %ebx
+		movl	chainlenwmask(%esp), %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	nicematch(%esp), %ebx
+		movl	%eax, bestlen(%esp)
+		movl	%ecx, dsMatchStart(%edx)
+		cmpl	%ebx, %eax
+		jge	LeaveNow
+		movl	window(%esp), %esi
+		addl	%eax, %esi
+		movl	%esi, windowbestlen(%esp)
+		movzwl	-1(%edi,%eax), %ebx
+		movl	dsPrev(%edx), %edi
+		movl	%ebx, scanend(%esp)
+		movl	chainlenwmask(%esp), %edx
+		jmp	LookupLoop
+
+/* Accept the current string, with the maximum possible length.		*/
+
+LenMaximum:	movl	deflatestate(%esp), %edx
+		movl	$MAX_MATCH, bestlen(%esp)
+		movl	%ecx, dsMatchStart(%edx)
+
+/* if ((uInt)best_len <= s->lookahead) return (uInt)best_len;		*/
+/* return s->lookahead;							*/
+
+LeaveNow:
+		movl	deflatestate(%esp), %edx
+		movl	bestlen(%esp), %ebx
+		movl	dsLookahead(%edx), %eax
+		cmpl	%eax, %ebx
+		jg	LookaheadRet
+		movl	%ebx, %eax
+LookaheadRet:
+
+/* Restore the stack and return from whence we came.			*/
+
+		addl	$LocalVarsSize, %esp
+		.cfi_def_cfa_offset 20
+		popl	%ebx
+		.cfi_def_cfa_offset 16
+		popl	%esi
+		.cfi_def_cfa_offset 12
+		popl	%edi
+		.cfi_def_cfa_offset 8
+		popl	%ebp
+		.cfi_def_cfa_offset 4
+.cfi_endproc
+match_init:	ret