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Rev	Author	Line No.	Line
6725	siemargl	1	/*
		2	Copyright (c) 1990-2007 Info-ZIP. All rights reserved.
		3
		4	See the accompanying file LICENSE, version 2000-Apr-09 or later
		5	(the contents of which are also included in zip.h) for terms of use.
		6	If, for some reason, all these files are missing, the Info-ZIP license
		7	also may be found at: ftp://ftp.info-zip.org/pub/infozip/license.html
		8	*/
		9	/*
		10	* crc_i386.S, optimized CRC calculation function for Zip and UnZip,
		11	* created by Paul Kienitz and Christian Spieler. Last revised 07 Jan 2007.
		12	*
		13	* GRR 961110: incorporated Scott Field optimizations from win32/crc_i386.asm
		14	* => overall 6% speedup in "unzip -tq" on 9MB zipfile (486-66)
		15	*
		16	* SPC 970402: revised for Rodney Brown's optimizations (32-bit-wide
		17	* aligned reads for most of the data from buffer), can be
		18	* disabled by defining the macro NO_32_BIT_LOADS
		19	*
		20	* SPC 971012: added Rodney Brown's additional tweaks for 32-bit-optimized
		21	* CPUs (like the Pentium Pro, Pentium II, and probably some
		22	* Pentium clones). This optimization is controlled by the
		23	* preprocessor switch "__686" and is disabled by default.
		24	* (This default is based on the assumption that most users
		25	* do not yet work on a Pentium Pro or Pentium II machine ...)
		26	*
		27	* COS 050116: Enabled the 686 build by default, because there are hardly any
		28	* pre-686 CPUs in serious use nowadays. (See SPC 970402 above.)
		29	*
		30	* SPC 060103: Updated code to incorporate newer optimizations found in zlib.
		31	*
		32	* SPC 070107: Added conditional switch to deactivate crc32() compilation.
		33	*
		34	* FLAT memory model assumed. Calling interface:
		35	* - args are pushed onto the stack from right to left,
		36	* - return value is given in the EAX register,
		37	* - all other registers (with exception of EFLAGS) are preserved. (With
		38	* GNU C 2.7.x, %edx and %ecx are `scratch' registers, but preserving
		39	* them nevertheless adds only 4 single byte instructions.)
		40	*
		41	* This source generates the function
		42	* ulg crc32(ulg crc, ZCONST uch *buf, extent len).
		43	*
		44	* Loop unrolling can be disabled by defining the macro NO_UNROLLED_LOOPS.
		45	* This results in shorter code at the expense of reduced performance.
		46	*/
		47
		48	/* This file is NOT used in conjunction with zlib, or when only creation of
		49	* the basic CRC_32_Table (for other purpose) is requested.
		50	*/
		51	#if !defined(USE_ZLIB) && !defined(CRC_TABLE_ONLY)
		52
		53	/* Preprocess with -DNO_UNDERLINE if your C compiler does not prefix
		54	* external symbols with an underline character '_'.
		55	*/
		56	#if defined(NO_UNDERLINE) \|\| defined(__ELF__)
		57	# define _crc32 crc32
		58	# define _get_crc_table get_crc_table
		59	#endif
		60	/* Use 16-byte alignment if your assembler supports it. Warning: gas
		61	* uses a log(x) parameter (.align 4 means 16-byte alignment). On SVR4
		62	* the parameter is a number of bytes.
		63	*/
		64	#ifndef ALIGNMENT
		65	# define ALIGNMENT .align 4,0x90
		66	#endif
		67
		68	#if defined(i386) \|\| defined(_i386) \|\| defined(_I386) \|\| defined(__i386)
		69
		70	/* This version is for 386 Unix, OS/2, MSDOS in 32 bit mode (gcc & gas).
		71	* Warning: it uses the AT&T syntax: mov source,dest
		72	* This file is only optional. If you want to use the C version,
		73	* remove -DASM_CRC from CFLAGS in Makefile and set OBJA to an empty string.
		74	*/
		75
		76	.file "crc_i386.S"
		77
		78	#if !defined(PRE_686) && !defined(__686)
		79	/* Optimize for Pentium Pro and compatible CPUs by default. */
		80	# define __686
		81	#endif
		82
		83	#if defined(NO_STD_STACKFRAME) && defined(USE_STD_STACKFRAME)
		84	# undef USE_STACKFRAME
		85	#else
		86	/* The default is to use standard stack frame entry, because it
		87	* results in smaller code!
		88	*/
		89	# ifndef USE_STD_STACKFRAME
		90	# define USE_STD_STACKFRAME
		91	# endif
		92	#endif
		93
		94	#ifdef USE_STD_STACKFRAME
		95	# define _STD_ENTRY pushl %ebp ; movl %esp,%ebp
		96	# define arg1 8(%ebp)
		97	# define arg2 12(%ebp)
		98	# define arg3 16(%ebp)
		99	# define _STD_LEAVE popl %ebp
		100	#else /* !USE_STD_STACKFRAME */
		101	# define _STD_ENTRY
		102	# define arg1 24(%esp)
		103	# define arg2 28(%esp)
		104	# define arg3 32(%esp)
		105	# define _STD_LEAVE
		106	#endif /* ?USE_STD_STACKFRAME */
		107
		108	/*
		109	* These two (three) macros make up the loop body of the CRC32 cruncher.
		110	* registers modified:
		111	* eax : crc value "c"
		112	* esi : pointer to next data byte (or lword) "buf++"
		113	* registers read:
		114	* edi : pointer to base of crc_table array
		115	* scratch registers:
		116	* ebx : index into crc_table array
		117	* (requires upper three bytes = 0 when __686 is undefined)
		118	*/
		119	#ifndef __686 /* optimize for 386, 486, Pentium */
		120	#define Do_CRC /* c = (c >> 8) ^ table[c & 0xFF] */\
		121	movb %al, %bl ;/* tmp = c & 0xFF */\
		122	shrl $8, %eax ;/* c = (c >> 8) */\
		123	xorl (%edi, %ebx, 4), %eax ;/* c ^= table[tmp] */
		124	#else /* __686 : optimize for Pentium Pro and compatible CPUs */
		125	#define Do_CRC /* c = (c >> 8) ^ table[c & 0xFF] */\
		126	movzbl %al, %ebx ;/* tmp = c & 0xFF */\
		127	shrl $8, %eax ;/* c = (c >> 8) */\
		128	xorl (%edi, %ebx, 4), %eax ;/* c ^=table[tmp] */
		129	#endif /* ?__686 */
		130
		131	#define Do_CRC_byte /* c = (c >> 8) ^ table[(c^buf++)&0xFF] /\
		132	xorb (%esi), %al ;/* c ^= buf /\
		133	incl %esi ;/* buf++ */\
		134	Do_CRC
		135
		136	#define Do_CRC_byteof(ofs) /* c = (c >> 8) ^ table[(c^buf++)&0xFF] /\
		137	xorb ofs(%esi), %al ;/* c ^= buf /\
		138	incl %esi ;/* buf++ */\
		139	Do_CRC
		140
		141	#ifndef NO_32_BIT_LOADS
		142	# ifdef IZ_CRCOPTIM_UNFOLDTBL
		143	/* the edx register is needed in crc calculation */
		144	# define SavLen arg3
		145	# define UpdCRC_lword \
		146	movzbl %al, %ebx ; \
		147	movl 3072(%edi,%ebx,4), %edx ; \
		148	movzbl %ah, %ebx ; \
		149	shrl $16, %eax ; \
		150	xor 2048(%edi,%ebx,4), %edx ; \
		151	movzbl %al, %ebx ; \
		152	shrl $8,%eax ; \
		153	xorl 1024(%edi,%ebx,4), %edx ; \
		154	movl (%edi,%eax,4), %eax ; \
		155	xorl %edx,%eax ;
		156	# define UpdCRC_lword_sh(dwPtrIncr) \
		157	movzbl %al, %ebx ; \
		158	movl 3072(%edi,%ebx,4), %edx ; \
		159	movzbl %ah, %ebx ; \
		160	shrl $16, %eax ; \
		161	xor 2048(%edi,%ebx,4), %edx ; \
		162	movzbl %al, %ebx ; \
		163	addl $4(dwPtrIncr), %esi ;/ ((ulg )buf)+=dwPtrIncr /\
		164	shrl $8,%eax ; \
		165	xorl 1024(%edi,%ebx,4), %edx ; \
		166	movl (%edi,%eax,4),%eax ; \
		167	xorl %edx,%eax ;
		168	# else /* !IZ_CRCOPTIM_UNFOLDTBL */
		169	/* the edx register is not needed anywhere else */
		170	# define SavLen %edx
		171	# define UpdCRC_lword \
		172	Do_CRC \
		173	Do_CRC \
		174	Do_CRC \
		175	Do_CRC
		176	# define UpdCRC_lword_sh(dwPtrIncr) \
		177	Do_CRC \
		178	Do_CRC \
		179	addl $4(dwPtrIncr), %esi ;/ ((ulg )buf)++ /\
		180	Do_CRC \
		181	Do_CRC
		182	# endif /* ?IZ_CRCOPTIM_UNFOLDTBL */
		183	#define Do_CRC_lword \
		184	xorl (%esi), %eax ;/* c ^= (ulg )buf */\
		185	UpdCRC_lword_sh(1) /* ... ((ulg )buf)++ /
		186	#define Do_CRC_4lword \
		187	xorl (%esi), %eax ;/* c ^= (ulg )buf */\
		188	UpdCRC_lword \
		189	xorl 4(%esi), %eax ;/* c ^= ((ulg )buf+1) */\
		190	UpdCRC_lword \
		191	xorl 8(%esi), %eax ;/* c ^= ((ulg )buf+2) */\
		192	UpdCRC_lword \
		193	xorl 12(%esi), %eax ;/* c ^= ((ulg )buf]+3 */\
		194	UpdCRC_lword_sh(4) /* ... ((ulg )buf)+=4 /
		195	#endif /* !NO_32_BIT_LOADS */
		196
		197
		198	.text
		199
		200	.globl _crc32
		201
		202	_crc32: /* ulg crc32(ulg crc, uch buf, extent len) /
		203	_STD_ENTRY
		204	pushl %edi
		205	pushl %esi
		206	pushl %ebx
		207	pushl %edx
		208	pushl %ecx
		209
		210	movl arg2, %esi /* 2nd arg: uch buf /
		211	subl %eax, %eax /* > if (!buf) */
		212	testl %esi, %esi /* > return 0; */
		213	jz .L_fine /* > else { */
		214	call _get_crc_table
		215	movl %eax, %edi
		216	movl arg1, %eax /* 1st arg: ulg crc */
		217	#ifndef __686
		218	subl %ebx, %ebx /* ebx=0; bl usable as dword */
		219	#endif
		220	movl arg3, %ecx /* 3rd arg: extent len */
		221	notl %eax /* > c = ~crc; */
		222
		223	testl %ecx, %ecx
		224	#ifndef NO_UNROLLED_LOOPS
		225	jz .L_bail
		226	# ifndef NO_32_BIT_LOADS
		227	/* Assert now have positive length */
		228	.L_align_loop:
		229	testl $3, %esi /* Align buf on lword boundary */
		230	jz .L_aligned_now
		231	Do_CRC_byte
		232	decl %ecx
		233	jnz .L_align_loop
		234	.L_aligned_now:
		235	# endif /* !NO_32_BIT_LOADS */
		236	movl %ecx, SavLen /* save current value of len */
		237	shrl $4, %ecx /* ecx = len / 16 */
		238	jz .L_No_Sixteens
		239	/* align loop head at start of 486 internal cache line !! */
		240	ALIGNMENT
		241	.L_Next_Sixteen:
		242	# ifndef NO_32_BIT_LOADS
		243	Do_CRC_4lword
		244	# else /* NO_32_BIT_LOADS */
		245	Do_CRC_byteof(0)
		246	Do_CRC_byteof(1)
		247	Do_CRC_byteof(2)
		248	Do_CRC_byteof(3)
		249	Do_CRC_byteof(4)
		250	Do_CRC_byteof(5)
		251	Do_CRC_byteof(6)
		252	Do_CRC_byteof(7)
		253	Do_CRC_byteof(8)
		254	Do_CRC_byteof(9)
		255	Do_CRC_byteof(10)
		256	Do_CRC_byteof(11)
		257	Do_CRC_byteof(12)
		258	Do_CRC_byteof(13)
		259	Do_CRC_byteof(14)
		260	Do_CRC_byteof(15)
		261	addl $16,%esi ;/* buf += 16 */
		262	# endif /* ?NO_32_BIT_LOADS */
		263	decl %ecx
		264	jnz .L_Next_Sixteen
		265
		266	.L_No_Sixteens:
		267	movl SavLen, %ecx
		268	andl $15, %ecx /* ecx = len % 16 */
		269	# ifndef NO_32_BIT_LOADS
		270	shrl $2,%ecx /* ecx = len / 4 */
		271	jz .L_No_Fours
		272	.L_Next_Four:
		273	Do_CRC_lword
		274	decl %ecx
		275	jnz .L_Next_Four
		276	.L_No_Fours:
		277	movl SavLen,%ecx
		278	andl $3,%ecx /* ecx = len % 4 */
		279	# endif /* !NO_32_BIT_LOADS */
		280	#endif /* !NO_UNROLLED_LOOPS */
		281	jz .L_bail /* > if (len) */
		282	/* align loop head at start of 486 internal cache line !! */
		283	ALIGNMENT
		284	.L_loupe: /* > do { */
		285	Do_CRC_byte /* c = CRC32(c,buf++,crctab);/
		286	decl %ecx /* > } while (--len); */
		287	jnz .L_loupe
		288
		289	.L_bail: /* > } */
		290	notl %eax /* > return ~c; */
		291	.L_fine:
		292	popl %ecx
		293	popl %edx
		294	popl %ebx
		295	popl %esi
		296	popl %edi
		297	_STD_LEAVE
		298	ret
		299
		300	#else
		301	error: this asm version is for 386 only
		302	#endif /* i386 \|\| _i386 \|\| _I386 \|\| __i386 */
		303
		304	#endif /* !USE_ZLIB && !CRC_TABLE_ONLY */

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