233 lines
8.7 KiB
ArmAsm
233 lines
8.7 KiB
ArmAsm
/*
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Copyright (c) 1990-2001 Info-ZIP. All rights reserved.
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See the accompanying file LICENSE, version 2000-Apr-09 or later
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(the contents of which are also included in zip.h) for terms of use.
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If, for some reason, all these files are missing, the Info-ZIP license
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also may be found at: ftp://ftp.info-zip.org/pub/infozip/license.html
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*/
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/*
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* crc_i386.S, optimized CRC calculation function for Zip and UnZip,
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* created by Paul Kienitz and Christian Spieler. Last revised 24 Dec 98.
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*
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* GRR 961110: incorporated Scott Field optimizations from win32/crc_i386.asm
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* => overall 6% speedup in "unzip -tq" on 9MB zipfile (486-66)
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*
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* SPC 970402: revised for Rodney Brown's optimizations (32-bit-wide
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* aligned reads for most of the data from buffer), can be
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* disabled by defining the macro NO_32_BIT_LOADS
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*
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* SPC 971012: added Rodney Brown's additional tweaks for 32-bit-optimized
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* CPUs (like the Pentium Pro, Pentium II, and probably some
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* Pentium clones). This optimization is controlled by the
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* preprocessor switch "__686" and is disabled by default.
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* (This default is based on the assumption that most users
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* do not yet work on a Pentium Pro or Pentium II machine ...)
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*
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* FLAT memory model assumed. Calling interface:
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* - args are pushed onto the stack from right to left,
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* - return value is given in the EAX register,
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* - all other registers (with exception of EFLAGS) are preserved. (With
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* GNU C 2.7.x, %edx and %ecx are `scratch' registers, but preserving
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* them nevertheless adds only 4 single byte instructions.)
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*
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* This source generates the function
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* ulg crc32(ulg crc, ZCONST uch *buf, extent len).
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*
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* The loop unrolling can be disabled by defining the macro NO_UNROLLED_LOOPS.
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* This results in shorter code at the expense of reduced performance.
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*/
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/* This file is NOT used in conjunction with zlib. */
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#ifndef USE_ZLIB
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/* Preprocess with -DNO_UNDERLINE if your C compiler does not prefix
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* external symbols with an underline character '_'.
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*/
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#if defined(NO_UNDERLINE) || defined(__ELF__)
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# define _crc32 crc32
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# define _get_crc_table get_crc_table
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#endif
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/* Use 16-byte alignment if your assembler supports it. Warning: gas
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* uses a log(x) parameter (.align 4 means 16-byte alignment). On SVR4
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* the parameter is a number of bytes.
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*/
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#ifndef ALIGNMENT
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# define ALIGNMENT .align 4,0x90
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#endif
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#if defined(i386) || defined(_i386) || defined(_I386) || defined(__i386)
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/* This version is for 386 Unix, OS/2, MSDOS in 32 bit mode (gcc & gas).
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* Warning: it uses the AT&T syntax: mov source,dest
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* This file is only optional. If you want to use the C version,
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* remove -DASM_CRC from CFLAGS in Makefile and set OBJA to an empty string.
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*/
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.file "crc_i386.S"
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#if defined(NO_STD_STACKFRAME) && defined(USE_STD_STACKFRAME)
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# undef USE_STACKFRAME
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#else
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/* The default is to use standard stack frame entry, because it
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* results in smaller code!
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*/
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# ifndef USE_STD_STACKFRAME
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# define USE_STD_STACKFRAME
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# endif
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#endif
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#ifdef USE_STD_STACKFRAME
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# define _STD_ENTRY pushl %ebp ; movl %esp,%ebp
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# define arg1 8(%ebp)
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# define arg2 12(%ebp)
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# define arg3 16(%ebp)
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# define _STD_LEAVE popl %ebp
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#else /* !USE_STD_STACKFRAME */
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# define _STD_ENTRY
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# define arg1 24(%esp)
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# define arg2 28(%esp)
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# define arg3 32(%esp)
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# define _STD_LEAVE
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#endif /* ?USE_STD_STACKFRAME */
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/*
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* These two (three) macros make up the loop body of the CRC32 cruncher.
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* registers modified:
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* eax : crc value "c"
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* esi : pointer to next data byte (or lword) "buf++"
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* registers read:
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* edi : pointer to base of crc_table array
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* scratch registers:
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* ebx : index into crc_table array
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* (requires upper three bytes = 0 when __686 is undefined)
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*/
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#ifndef __686 /* optimize for 386, 486, Pentium */
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#define Do_CRC /* c = (c >> 8) ^ table[c & 0xFF] */\
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movb %al, %bl ;/* tmp = c & 0xFF */\
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shrl $8, %eax ;/* c = (c >> 8) */\
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xorl (%edi, %ebx, 4), %eax ;/* c ^= table[tmp] */
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#else /* __686 : optimize for Pentium Pro and compatible CPUs */
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#define Do_CRC /* c = (c >> 8) ^ table[c & 0xFF] */\
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movzbl %al, %ebx ;/* tmp = c & 0xFF */\
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shrl $8, %eax ;/* c = (c >> 8) */\
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xorl (%edi, %ebx, 4), %eax ;/* c ^=table[tmp] */
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#endif /* ?__686 */
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#define Do_CRC_byte /* c = (c >> 8) ^ table[(c^*buf++)&0xFF] */\
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xorb (%esi), %al ;/* c ^= *buf */\
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incl %esi ;/* buf++ */\
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Do_CRC
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#ifndef NO_32_BIT_LOADS
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#define Do_CRC_lword \
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xorl (%esi), %eax ;/* c ^= *(ulg *)buf */\
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addl $4, %esi ;/* ((ulg *)buf)++ */\
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Do_CRC \
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Do_CRC \
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Do_CRC \
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Do_CRC
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#endif /* !NO_32_BIT_LOADS */
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.text
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.globl _crc32
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_crc32: /* ulg crc32(ulg crc, uch *buf, extent len) */
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_STD_ENTRY
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pushl %edi
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pushl %esi
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pushl %ebx
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pushl %edx
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pushl %ecx
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movl arg2, %esi /* 2nd arg: uch *buf */
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subl %eax, %eax /* > if (!buf) */
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testl %esi, %esi /* > return 0; */
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jz .L_fine /* > else { */
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call _get_crc_table
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movl %eax, %edi
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movl arg1, %eax /* 1st arg: ulg crc */
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#ifndef __686
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subl %ebx, %ebx /* ebx=0; bl usable as dword */
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#endif
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movl arg3, %ecx /* 3rd arg: extent len */
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notl %eax /* > c = ~crc; */
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testl %ecx, %ecx
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#ifndef NO_UNROLLED_LOOPS
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jz .L_bail
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# ifndef NO_32_BIT_LOADS
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/* Assert now have positive length */
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.L_align_loop:
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testl $3, %esi /* Align buf on lword boundary */
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jz .L_aligned_now
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Do_CRC_byte
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decl %ecx
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jnz .L_align_loop
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.L_aligned_now:
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# endif /* !NO_32_BIT_LOADS */
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movl %ecx, %edx /* save len in edx */
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shrl $3, %ecx /* ecx = len / 8 */
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jz .L_No_Eights
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/* align loop head at start of 486 internal cache line !! */
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ALIGNMENT
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.L_Next_Eight:
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# ifndef NO_32_BIT_LOADS
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/* Do_CRC_lword */
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xorl (%esi), %eax ;/* c ^= *(ulg *)buf */
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addl $4, %esi ;/* ((ulg *)buf)++ */
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Do_CRC
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Do_CRC
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Do_CRC
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Do_CRC
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/* Do_CRC_lword */
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xorl (%esi), %eax ;/* c ^= *(ulg *)buf */
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addl $4, %esi ;/* ((ulg *)buf)++ */
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Do_CRC
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Do_CRC
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Do_CRC
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Do_CRC
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# else /* NO_32_BIT_LOADS */
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Do_CRC_byte
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Do_CRC_byte
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Do_CRC_byte
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Do_CRC_byte
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Do_CRC_byte
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Do_CRC_byte
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Do_CRC_byte
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Do_CRC_byte
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# endif /* ?NO_32_BIT_LOADS */
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decl %ecx
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jnz .L_Next_Eight
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.L_No_Eights:
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movl %edx, %ecx
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andl $7, %ecx /* ecx = len % 8 */
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#endif /* !NO_UNROLLED_LOOPS */
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jz .L_bail /* > if (len) */
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/* align loop head at start of 486 internal cache line !! */
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ALIGNMENT
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.L_loupe: /* > do { */
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Do_CRC_byte /* c = CRC32(c, *buf++); */
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decl %ecx /* > } while (--len); */
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jnz .L_loupe
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.L_bail: /* > } */
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notl %eax /* > return ~c; */
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.L_fine:
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popl %ecx
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popl %edx
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popl %ebx
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popl %esi
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popl %edi
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_STD_LEAVE
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ret
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#else
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error: this asm version is for 386 only
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#endif /* i386 || _i386 || _I386 || __i386 */
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#endif /* !USE_ZLIB */
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