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Diffstat (limited to 'sysdeps/i386/strcspn.S')
| -rw-r--r-- | sysdeps/i386/strcspn.S | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/sysdeps/i386/strcspn.S b/sysdeps/i386/strcspn.S new file mode 100644 index 0000000000..b0e789b490 --- /dev/null +++ b/sysdeps/i386/strcspn.S @@ -0,0 +1,176 @@ +/* strcspn (str, ss) -- Return the length of the initial segement of STR + which contains no characters from SS. +For Intel 80x86, x>=3. +Copyright (C) 1994, 1995 Free Software Foundation, Inc. +Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu> +Bug fixes by Alan Modra <Alan@SPRI.Levels.UniSA.Edu.Au> +This file is part of the GNU C Library. + +The GNU C Library is free software; you can redistribute it and/or +modify it under the terms of the GNU Library General Public License as +published by the Free Software Foundation; either version 2 of the +License, or (at your option) any later version. + +The GNU C Library is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +Library General Public License for more details. + +You should have received a copy of the GNU Library General Public +License along with the GNU C Library; see the file COPYING.LIB. If +not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, +Boston, MA 02111-1307, USA. */ + +#include <sysdep.h> +#include "asm-syntax.h" + +/* + INPUT PARAMETERS: + str (sp + 4) + stopset (sp + 8) +*/ + + .text +ENTRY (strcspn) + movl 4(%esp), %edx /* get string pointer */ + movl 8(%esp), %eax /* get stopset pointer */ + + /* First we create a table with flags for all possible characters. + For the ASCII (7bit/8bit) or ISO-8859-X character sets which are + supported by the C string functions we have 256 characters. + Before inserting marks for the stop characters we clear the whole + table. The unrolled form is much faster than a loop. */ + xorl %ecx, %ecx /* %ecx = 0 !!! */ + + pushl %ecx /* make a 256 bytes long block filled with 0 */ + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl %ecx + pushl $0 /* These immediate values make the label 2 */ + pushl $0 /* to be aligned on a 16 byte boundary to */ + pushl $0 /* get a better performance of the loop. */ + pushl $0 + pushl $0 + pushl $0 + +/* For understanding the following code remember that %ecx == 0 now. + Although all the following instruction only modify %cl we always + have a correct zero-extended 32-bit value in %ecx. */ + +/* Don't change the "testb $0xff,%%cl" to "testb %%cl,%%cl". We want + longer instructions so that the next loop aligns without adding nops. */ + +L2: movb (%eax), %cl /* get byte from stopset */ + testb %cl, %cl /* is NUL char? */ + jz L1 /* yes => start compare loop */ + movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */ + + movb 1(%eax), %cl /* get byte from stopset */ + testb $0xff, %cl /* is NUL char? */ + jz L1 /* yes => start compare loop */ + movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */ + + movb 2(%eax), %cl /* get byte from stopset */ + testb $0xff, %cl /* is NUL char? */ + jz L1 /* yes => start compare loop */ + movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */ + + movb 3(%eax), %cl /* get byte from stopset */ + addl $4, %eax /* increment stopset pointer */ + movb %cl, (%esp,%ecx) /* set corresponding byte in stopset table */ + testb $0xff, %cl /* is NUL char? */ + jnz L2 /* no => process next dword from stopset */ + +L1: leal -4(%edx), %eax /* prepare loop */ + + /* We use a neat trick for the following loop. Normally we would + have to test for two termination conditions + 1. a character in the stopset was found + and + 2. the end of the string was found + But as a sign that the chracter is in the stopset we store its + value in the table. But the value of NUL is NUL so the loop + terminates for NUL in every case. */ + +L3: addl $4, %eax /* adjust pointer for full loop round */ + + movb (%eax), %cl /* get byte from string */ + cmpb %cl, (%esp,%ecx) /* is it contained in stopset? */ + je L4 /* yes => return */ + + movb 1(%eax), %cl /* get byte from string */ + cmpb %cl, (%esp,%ecx) /* is it contained in stopset? */ + je L5 /* yes => return */ + + movb 2(%eax), %cl /* get byte from string */ + cmpb %cl, (%esp,%ecx) /* is it contained in stopset? */ + je L6 /* yes => return */ + + movb 3(%eax), %cl /* get byte from string */ + cmpb %cl, (%esp,%ecx) /* is it contained in stopset? */ + jne L3 /* yes => return */ + + incl %eax /* adjust pointer */ +L6: incl %eax +L5: incl %eax + +L4: subl %edx, %eax /* we have to return the number of valid + characters, so compute distance to first + non-valid character */ + addl $256, %esp /* remove stopset */ + + ret |