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183 lines
5.2 KiB
ArmAsm
183 lines
5.2 KiB
ArmAsm
/* strcspn (str, ss) -- Return the length of the initial segment of STR
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which contains only characters from SS.
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For Intel 80x86, x>=3.
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Copyright (C) 1994-1997, 2000, 2003 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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Bug fixes by Alan Modra <Alan@SPRI.Levels.UniSA.Edu.Au>
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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 Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the 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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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <sysdep.h>
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#include "asm-syntax.h"
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#include "bp-sym.h"
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#include "bp-asm.h"
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#define PARMS LINKAGE /* no space for saved regs */
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#define STR PARMS
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#define SKIP STR+PTR_SIZE
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.text
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ENTRY (BP_SYM (strspn))
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ENTER
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movl STR(%esp), %edx
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movl SKIP(%esp), %eax
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CHECK_BOUNDS_LOW (%edx, STR(%esp))
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/* First we create a table with flags for all possible characters.
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For the ASCII (7bit/8bit) or ISO-8859-X character sets which are
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supported by the C string functions we have 256 characters.
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Before inserting marks for the stop characters we clear the whole
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table. The unrolled form is much faster than a loop. */
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xorl %ecx, %ecx /* %ecx = 0 !!! */
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pushl %ecx /* make a 256 bytes long block filled with 0 */
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl %ecx
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pushl $0 /* These immediate values make the label 2 */
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pushl $0 /* to be aligned on a 16 byte boundary to */
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pushl $0 /* get a better performance of the loop. */
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pushl $0
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pushl $0
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pushl $0
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/* For understanding the following code remember that %ecx == 0 now.
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Although all the following instruction only modify %cl we always
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have a correct zero-extended 32-bit value in %ecx. */
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/* Don't change the "testb $0xff,%%cl" to "testb %%cl,%%cl". We want
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longer instructions so that the next loop aligns without adding nops. */
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L(2): movb (%eax), %cl /* get byte from stopset */
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testb %cl, %cl /* is NUL char? */
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jz L(1) /* yes => start compare loop */
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movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */
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movb 1(%eax), %cl /* get byte from stopset */
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testb $0xff, %cl /* is NUL char? */
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jz L(1) /* yes => start compare loop */
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movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */
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movb 2(%eax), %cl /* get byte from stopset */
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testb $0xff, %cl /* is NUL char? */
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jz L(1) /* yes => start compare loop */
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movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */
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movb 3(%eax), %cl /* get byte from stopset */
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addl $4, %eax /* increment stopset pointer */
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movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */
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testb $0xff, %cl /* is NUL char? */
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jnz L(2) /* no => process next dword from stopset */
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L(1): leal -4(%edx), %eax /* prepare loop */
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/* We use a neat trick for the following loop. Normally we would
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have to test for two termination conditions
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1. a character in the stopset was found
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and
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2. the end of the string was found
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But as a sign that the character is in the stopset we store its
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value in the table. But the value of NUL is NUL so the loop
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terminates for NUL in every case. */
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L(3): addl $4, %eax /* adjust pointer for full loop round */
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movb (%eax), %cl /* get byte from string */
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testb %cl, (%esp,%ecx) /* is it contained in skipset? */
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jz L(4) /* no => return */
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movb 1(%eax), %cl /* get byte from string */
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testb %cl, (%esp,%ecx) /* is it contained in skipset? */
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jz L(5) /* no => return */
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movb 2(%eax), %cl /* get byte from string */
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testb %cl, (%esp,%ecx) /* is it contained in skipset? */
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jz L(6) /* no => return */
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movb 3(%eax), %cl /* get byte from string */
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testb %cl, (%esp,%ecx) /* is it contained in skipset? */
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jnz L(3) /* yes => start loop again */
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incl %eax /* adjust pointer */
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L(6): incl %eax
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L(5): incl %eax
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L(4): addl $256, %esp /* remove stopset */
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CHECK_BOUNDS_HIGH (%eax, STR(%esp), jb)
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subl %edx, %eax /* we have to return the number of valid
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characters, so compute distance to first
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non-valid character */
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LEAVE
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ret
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END (BP_SYM (strspn))
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libc_hidden_builtin_def (strspn)
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