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Thu Dec 19 23:28:33 1996 Ulrich Drepper <drepper@cygnus.com> * resolv/resolv.h: Update from BIND 4.9.5-P1. * resolv/res_comp.c: Likewise. * resolv/res_debug.c: Likewise. * resolv/Banner: Update version number. Thu Dec 19 20:58:53 1996 Ulrich Drepper <drepper@cygnus.com> * elf/dlfcn.h: Add extern "C" wrapper. * io/utime.h: Don't define NULL since this isn't allowed in POSIX. * io/sys/stat.h: Declare `lstat' only if __USE_BSD || __USE_XOPEN_EXTENDED. * locale/locale.h: Define NULL. * math/math.c: Don't include <errno.h> to define math errors. * stdlib/stdlib.h: Likewise. * posix/unistd.h: Don't declare environ. * posix/sys/utsname.h (struct utsname): Declare member domainname as __domainname is !__USE_GNU. * signal/signal.h: Declare size_t only if __USE_BSD || __USE_XOPEN_EXTENDED. * stdio/stdio.h: Don't declare cuserid when __USE_POSIX, but instead when __USE_XOPEN. * string/string.h: Define strndup only if __USE_GNU. * sysdeps/unix/sysv/linux/clock.c: New file. * sysdeps/unix/sysv/linux/timebits.h: Define CLOCKS_PER_SEC as 1000000 per X/Open standard. * features.h: Add code to recognize _POSIX_C_SOURCE value 199309. Define __USE_POSIX199309. * posix/unistd.h: Declare fdatasync only if __USE_POSIX199309. * time/time.c: Declare nanosleep only if __USE_POSIX199309. Patches by Rüdiger Helsch <rh@unifix.de>. * locale/locale.h: Add declaration of newlocale and freelocale. * new-malloc/Makefile (distibute): Add mtrace.awk. (dist-routines): Add mcheck and mtrace. (install-lib, non-lib.a): Define as libmcheck.a. * new-malloc/malloc.h: Add declaration of __malloc_initialized. * new-malloc/mcheck.c: New file. * new-malloc/mcheck.h: New file. * new-malloc/mtrace.c: New file. * new-malloc/mtrace.awk: New file. * posix/unistd.h: Correct prototype for usleep. * sysdeps/unix/bsd/usleep.c: De-ANSI-declfy. Correct return type. * sysdeps/unix/sysv/linux/usleep.c: Real implementation based on nanosleep. * signal/signal.h: Change protoype of __sigpause to take two arguments. Remove prototype for sigpause. Add two different macros named sigpause selected when __USE_BSD or __USE_XOPEN are defined. This is necessary since the old BSD definition of theis function collides with the X/Open definition. * sysdeps/posix/sigpause.c: Change function definition to also fit X/Open definition. * sysdeps/libm-i387/e_exp.S: Make sure stack is empty when the function is left. * sysdeps/libm-i387/e_expl.S: Likewise. Patch by HJ Lu. 1996-12-17 Paul Eggert <eggert@twinsun.com> * many, many files: Spelling corrections. * catgets/catgetsinfo.h (mmapped): Renamed from mmaped (in struct catalog_info.status). * mach/err_kern.sub (err_codes_unix), string/stratcliff.c (main): Fix spelling in message. * po/libc.pot: Fix spelling in message for `zic'; this anticipates a fix in the tzcode distribution. Wed Dec 18 15:48:02 1996 Ulrich Drepper <drepper@cygnus.com> * time/strftime.c: Implement ^ flag to cause output be converted to use upper case characters. * time/zic.c: Update from ADO tzcode1996n. Wed Dec 18 14:29:24 1996 Erik Naggum <erik@naggum.no> * time/strftime.c (add): Don't change global `i' until all is over. Define NULL is not already defined. Tue Dec 17 09:49:03 1996 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * libio/iovsprintf.c (_IO_vsprintf): Change `&sf' to `&sf._sbf._f' to avoid the need for a cast. * libio/iovsscanf.c (_IO_vsscanf): Likewise. * sunrpc/rpc/xdr.h: Add prototype for xdr_free.
184 lines
5.5 KiB
ArmAsm
184 lines
5.5 KiB
ArmAsm
/* strlen -- Compute length og NUL terminated string.
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Highly optimized version for ix86, x>=5.
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Copyright (C) 1995, 1996 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper, <drepper@gnu.ai.mit.edu>.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <sysdep.h>
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/* This version is especially optimized for the i586 (and following?)
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processors. This is mainly done by using the two pipelines. The
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version optimized for i486 is weak in this aspect because to get
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as much parallelism we have to execute some *more* instructions.
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The code below is structured to reflect the pairing of the instructions
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as *I think* it is. I have no processor data book to verify this.
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If you find something you think is incorrect let me know. */
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/* The magic value which is used throughout in the whole code. */
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#define magic 0xfefefeff
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/*
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INPUT PARAMETERS:
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str (sp + 4)
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*/
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.text
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ENTRY(strlen)
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movl 4(%esp), %eax /* get string pointer */
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movl $3, %edx /* load mask (= 3) */
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andl %eax, %edx /* separate last two bits of address */
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jz L1 /* aligned => start loop */
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jp L0 /* exactly two bits set */
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cmpb %dh, (%eax) /* is byte NUL? */
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je L2 /* yes => return */
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incl %eax /* increment pointer */
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cmpb %dh, (%eax) /* is byte NUL? */
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je L2 /* yes => return */
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incl %eax /* increment pointer */
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xorl $2, %edx
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jz L1
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L0: cmpb %dh, (%eax) /* is byte NUL? */
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je L2 /* yes => return */
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incl %eax /* increment pointer */
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xorl %edx, %edx /* We need %edx == 0 for later */
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/* We exit the loop if adding MAGIC_BITS to LONGWORD fails to
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change any of the hole bits of LONGWORD.
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1) Is this safe? Will it catch all the zero bytes?
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Suppose there is a byte with all zeros. Any carry bits
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propagating from its left will fall into the hole at its
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least significant bit and stop. Since there will be no
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carry from its most significant bit, the LSB of the
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byte to the left will be unchanged, and the zero will be
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detected.
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2) Is this worthwhile? Will it ignore everything except
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zero bytes? Suppose every byte of LONGWORD has a bit set
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somewhere. There will be a carry into bit 8. If bit 8
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is set, this will carry into bit 16. If bit 8 is clear,
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one of bits 9-15 must be set, so there will be a carry
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into bit 16. Similarly, there will be a carry into bit
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24. If one of bits 24-31 is set, there will be a carry
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into bit 32 (=carry flag), so all of the hole bits will
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be changed.
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Note: %edx == 0 in any case here. */
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L1:
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movl (%eax), %ecx /* get word (= 4 bytes) in question */
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addl $4, %eax /* adjust pointer for *next* word */
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subl %ecx, %edx /* first step to negate word */
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addl $magic, %ecx /* add magic word */
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decl %edx /* complete negation of word */
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jnc L3 /* previous addl caused overflow? */
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xorl %ecx, %edx /* (word+magic)^word */
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andl $~magic, %edx /* any of the carry flags set? */
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jne L3 /* yes => determine byte */
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movl (%eax), %ecx /* get word (= 4 bytes) in question */
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addl $4, %eax /* adjust pointer for *next* word */
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subl %ecx, %edx /* first step to negate word */
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addl $magic, %ecx /* add magic word */
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decl %edx /* complete negation of word */
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jnc L3 /* previous addl caused overflow? */
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xorl %ecx, %edx /* (word+magic)^word */
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andl $~magic, %edx /* any of the carry flags set? */
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jne L3 /* yes => determine byte */
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movl (%eax), %ecx /* get word (= 4 bytes) in question */
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addl $4, %eax /* adjust pointer for *next* word */
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subl %ecx, %edx /* first step to negate word */
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addl $magic, %ecx /* add magic word */
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decl %edx /* complete negation of word */
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jnc L3 /* previous addl caused overflow? */
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xorl %ecx, %edx /* (word+magic)^word */
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andl $~magic, %edx /* any of the carry flags set? */
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jne L3 /* yes => determine byte */
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movl (%eax), %ecx /* get word (= 4 bytes) in question */
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addl $4, %eax /* adjust pointer for *next* word */
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subl %ecx, %edx /* first step to negate word */
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addl $magic, %ecx /* add magic word */
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decl %edx /* complete negation of word */
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jnc L3 /* previous addl caused overflow? */
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xorl %ecx, %edx /* (word+magic)^word */
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andl $~magic, %edx /* any of the carry flags set? */
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je L1 /* no => start loop again */
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L3: subl $4, %eax /* correct too early pointer increment */
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subl $magic, %ecx
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cmpb $0, %cl /* lowest byte NUL? */
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jz L2 /* yes => return */
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inc %eax /* increment pointer */
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testb %ch, %ch /* second byte NUL? */
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jz L2 /* yes => return */
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shrl $16, %ecx /* make upper bytes accessible */
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incl %eax /* increment pointer */
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cmpb $0, %cl /* is third byte NUL? */
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jz L2 /* yes => return */
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incl %eax /* increment pointer */
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L2: subl 4(%esp), %eax /* now compute the length as difference
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between start and terminating NUL
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character */
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ret
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END (strlen)
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