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newlib-cygwin/newlib/libc/machine/i386/strlen.S

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import newlib-2000-02-17 snapshot
2000-02-18 03:39:52 +08:00
/*
* ====================================================
2008-05-26 Eric Blake <ebb9@byu.net> Optimize the generic and x86 strlen. * libc/string/strlen.c (strlen) [!__OPTIMIZE_SIZE__]: Pre-align data so unaligned searches aren't penalized. * libc/machine/i386/strlen.S (strlen) [!__OPTIMIZE_SIZE__]: Word operations are faster than repnz byte searches.
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* Copyright (C) 1998, 2002, 2008 by Red Hat Inc. All rights reserved.
import newlib-2000-02-17 snapshot
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*
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
#include "i386mach.h"
.global SYM (strlen)
2000-08-27 Werner Almesberger <Werner.Almesberger@epfl.ch> * libc/machine/i386/i386mach.h: added SOTYPE_FUNCTION to set type of global entry points if _I386MACH_NEED_SOTYPE_FUNCTION is defined; Added __CLI and __STI macros (controlled via _I386MACH_ALLOW_HW_INTERRUPTS macro). * libc/machine/i386/f_atan2.S libc/machine/i386/f_atan2f.S libc/machine/i386/f_frexp.S libc/machine/i386/f_frexpf.S libc/machine/i386/f_ldexp.S libc/machine/i386/f_ldexpf.S libc/machine/i386/f_log.S libc/machine/i386/f_log10.S libc/machine/i386/f_log10f.S libc/machine/i386/f_logf.S libc/machine/i386/f_tan.S libc/machine/i386/f_tanf.S libc/machine/i386/memchr.S libc/machine/i386/memcmp.S libc/machine/i386/memcpy.S libc/machine/i386/memmove.S libc/machine/i386/memset.S libc/machine/i386/setjmp.S libc/machine/i386/strchr.S libc/machine/i386/strlen.S: (that's libc/machine/i386/*.S) added SOTYPE_FUNCTION(symbol) for all global entry points. * libc/machine/i386/setjmp.S: removed code replicated in libc/machine/i386/i386mach.h and included i386mach.h instead; Use __CLI and __STI instead of cli and sti.
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SOTYPE_FUNCTION(strlen)
import newlib-2000-02-17 snapshot
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SYM (strlen):
pushl ebp
movl esp,ebp
pushl edi
Add Intel MCU target Intel MCU System V ABI are incompartible with i386 System V ABI: o Minimum instruction set is Intel Pentium ISA minus x87 instructions o No x87 or vector registers o First three args are passed in %eax, %edx and %ecx o Full specification available here: https://github.com/hjl-tools/x86-psABI/wiki/iamcu-psABI-0.7.pdf newlib/ * configure.host: Add new ix86-*-elfiamcu target newlib/libc/include/ * setjmp.h: Change _JBLEN for Intel MCU target newlib/libc/machine/i386/ * memchr.S: (memchr) Target-specific size-optimized version * memcmp.S: (memcmp) Likewise * memcpy.S: (memcpy) Likewise * memmove.S: (memmove) Likewise * memset.S: (memset) Likewise * setjmp.S: (setjmp) Likewise * strchr.S: (strchr) Likewise * strlen.S: (strlen) Likewise newlib/libc/stdlib/ * srtold.c: (__flt_rounds) Disable for Intel MCU
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#ifdef __iamcu__
movl eax,edx
#else
import newlib-2000-02-17 snapshot
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movl 8(ebp),edx
Add Intel MCU target Intel MCU System V ABI are incompartible with i386 System V ABI: o Minimum instruction set is Intel Pentium ISA minus x87 instructions o No x87 or vector registers o First three args are passed in %eax, %edx and %ecx o Full specification available here: https://github.com/hjl-tools/x86-psABI/wiki/iamcu-psABI-0.7.pdf newlib/ * configure.host: Add new ix86-*-elfiamcu target newlib/libc/include/ * setjmp.h: Change _JBLEN for Intel MCU target newlib/libc/machine/i386/ * memchr.S: (memchr) Target-specific size-optimized version * memcmp.S: (memcmp) Likewise * memcpy.S: (memcpy) Likewise * memmove.S: (memmove) Likewise * memset.S: (memset) Likewise * setjmp.S: (setjmp) Likewise * strchr.S: (strchr) Likewise * strlen.S: (strlen) Likewise newlib/libc/stdlib/ * srtold.c: (__flt_rounds) Disable for Intel MCU
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#endif
import newlib-2000-02-17 snapshot
2000-02-18 03:39:52 +08:00
Add Intel MCU target Intel MCU System V ABI are incompartible with i386 System V ABI: o Minimum instruction set is Intel Pentium ISA minus x87 instructions o No x87 or vector registers o First three args are passed in %eax, %edx and %ecx o Full specification available here: https://github.com/hjl-tools/x86-psABI/wiki/iamcu-psABI-0.7.pdf newlib/ * configure.host: Add new ix86-*-elfiamcu target newlib/libc/include/ * setjmp.h: Change _JBLEN for Intel MCU target newlib/libc/machine/i386/ * memchr.S: (memchr) Target-specific size-optimized version * memcmp.S: (memcmp) Likewise * memcpy.S: (memcpy) Likewise * memmove.S: (memmove) Likewise * memset.S: (memset) Likewise * setjmp.S: (setjmp) Likewise * strchr.S: (strchr) Likewise * strlen.S: (strlen) Likewise newlib/libc/stdlib/ * srtold.c: (__flt_rounds) Disable for Intel MCU
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#if defined __OPTIMIZE_SIZE__ || defined __iamcu__
import newlib-2000-02-17 snapshot
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cld
movl edx,edi
movl $4294967295,ecx
xor eax,eax
repnz
scasb
2008-05-26 Eric Blake <ebb9@byu.net> Optimize the generic and x86 strlen. * libc/string/strlen.c (strlen) [!__OPTIMIZE_SIZE__]: Pre-align data so unaligned searches aren't penalized. * libc/machine/i386/strlen.S (strlen) [!__OPTIMIZE_SIZE__]: Word operations are faster than repnz byte searches.
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#else
/* Modern x86 hardware is much faster at double-word
manipulation than with bytewise repnz scasb. */
/* Do byte-wise checks until string is aligned. */
movl edx,edi
test $3,edi
je L5
movb (edi),cl
incl edi
testb cl,cl
je L15
test $3,edi
je L5
movb (edi),cl
incl edi
testb cl,cl
je L15
test $3,edi
je L5
movb (edi),cl
incl edi
testb cl,cl
je L15
L5:
subl $4,edi
/* loop performing 4 byte mask checking for desired 0 byte */
.p2align 4,,7
L10:
addl $4,edi
movl (edi),ecx
leal -16843009(ecx),eax
notl ecx
andl ecx,eax
testl $-2139062144,eax
je L10
/* Find which of four bytes is 0. */
notl ecx
incl edi
testb cl,cl
je L15
incl edi
shrl $8,ecx
testb cl,cl
je L15
incl edi
shrl $8,ecx
testb cl,cl
je L15
incl edi
#endif
L15:
import newlib-2000-02-17 snapshot
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subl edx,edi
leal -1(edi),eax
leal -4(ebp),esp
popl edi
leave
ret