| /* strcspn (str, ss) -- Return the length of the initial segment of STR |
| which contains only characters from SS. |
| For Intel 80x86, x>=3. |
| Copyright (C) 1994-2016 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu> |
| Bug fixes by Alan Modra <Alan@SPRI.Levels.UniSA.Edu.Au> |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 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 |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <sysdep.h> |
| #include "asm-syntax.h" |
| |
| #define PARMS 4 /* no space for saved regs */ |
| #define STR PARMS |
| #define SKIP STR+4 |
| |
| .text |
| ENTRY (strspn) |
| |
| movl STR(%esp), %edx |
| movl SKIP(%esp), %eax |
| |
| /* 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 */ |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl %ecx |
| cfi_adjust_cfa_offset (4) |
| pushl $0 /* These immediate values make the label 2 */ |
| cfi_adjust_cfa_offset (4) |
| pushl $0 /* to be aligned on a 16 byte boundary to */ |
| cfi_adjust_cfa_offset (4) |
| pushl $0 /* get a better performance of the loop. */ |
| cfi_adjust_cfa_offset (4) |
| pushl $0 |
| cfi_adjust_cfa_offset (4) |
| pushl $0 |
| cfi_adjust_cfa_offset (4) |
| pushl $0 |
| cfi_adjust_cfa_offset (4) |
| |
| /* 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. */ |
| |
| L(2): movb (%eax), %cl /* get byte from stopset */ |
| testb %cl, %cl /* is NUL char? */ |
| jz L(1) /* 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 L(1) /* 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 L(1) /* 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 L(2) /* no => process next dword from stopset */ |
| |
| L(1): 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 character 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. */ |
| |
| L(3): addl $4, %eax /* adjust pointer for full loop round */ |
| |
| movb (%eax), %cl /* get byte from string */ |
| testb %cl, (%esp,%ecx) /* is it contained in skipset? */ |
| jz L(4) /* no => return */ |
| |
| movb 1(%eax), %cl /* get byte from string */ |
| testb %cl, (%esp,%ecx) /* is it contained in skipset? */ |
| jz L(5) /* no => return */ |
| |
| movb 2(%eax), %cl /* get byte from string */ |
| testb %cl, (%esp,%ecx) /* is it contained in skipset? */ |
| jz L(6) /* no => return */ |
| |
| movb 3(%eax), %cl /* get byte from string */ |
| testb %cl, (%esp,%ecx) /* is it contained in skipset? */ |
| jnz L(3) /* yes => start loop again */ |
| |
| incl %eax /* adjust pointer */ |
| L(6): incl %eax |
| L(5): incl %eax |
| |
| L(4): addl $256, %esp /* remove stopset */ |
| cfi_adjust_cfa_offset (-256) |
| subl %edx, %eax /* we have to return the number of valid |
| characters, so compute distance to first |
| non-valid character */ |
| ret |
| END (strspn) |
| libc_hidden_builtin_def (strspn) |