/* 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) 1994-1997, 2000, 2003 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper Bug fixes by Alan Modra 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, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ #include #include "asm-syntax.h" #include "bp-sym.h" #include "bp-asm.h" #define PARMS LINKAGE /* no space for saved regs */ #define STR PARMS #define SKIP STR+PTR_SIZE .text ENTRY (BP_SYM (strspn)) ENTER movl STR(%esp), %edx movl SKIP(%esp), %eax CHECK_BOUNDS_LOW (%edx, STR(%esp)) /* 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. */ 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 */ CHECK_BOUNDS_HIGH (%eax, STR(%esp), jb) subl %edx, %eax /* we have to return the number of valid characters, so compute distance to first non-valid character */ LEAVE ret END (BP_SYM (strspn)) libc_hidden_builtin_def (strspn)