/* strcspn (str, ss) -- Return the length of the initial segment of STR which contains no characters from SS. For AMD x86-64. Copyright (C) 1994-1997, 2000, 2002, 2003, 2004, 2005 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>. Adopted for x86-64 by Andreas Jaeger <aj@suse.de>. 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 "_glibc_inc.h" /* Seems to be unrolled too much */ /* BEWARE: `#ifdef strcspn' means that strcspn is redefined as `strpbrk' */ #define STRPBRK_P (defined strcspn) .text ENTRY (strcspn) movq %rdi, %rdx /* Save SRC. */ /* 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. */ movq %rdi, %r8 /* Save value. */ subq $256, %rsp /* Make space for 256 bytes. */ movl $32, %ecx /* 32*8 bytes = 256 bytes. */ movq %rsp, %rdi xorl %eax, %eax /* We store 0s. */ cld rep stosq movq %rsi, %rax /* Setup skipset. */ /* For understanding the following code remember that %rcx == 0 now. Although all the following instruction only modify %cl we always have a correct zero-extended 64-bit value in %rcx. */ /* Next 3 insns are 6 bytes total, make sure we decode them in one go */ .p2align 3,,6 L(2): movb (%rax), %cl /* get byte from skipset */ testb %cl, %cl /* is NUL char? */ jz L(1) /* yes => start compare loop */ movb %cl, (%rsp,%rcx) /* set corresponding byte in skipset table */ movb 1(%rax), %cl /* get byte from skipset */ testb %cl, %cl /* is NUL char? */ jz L(1) /* yes => start compare loop */ movb %cl, (%rsp,%rcx) /* set corresponding byte in skipset table */ movb 2(%rax), %cl /* get byte from skipset */ testb %cl, %cl /* is NUL char? */ jz L(1) /* yes => start compare loop */ movb %cl, (%rsp,%rcx) /* set corresponding byte in skipset table */ movb 3(%rax), %cl /* get byte from skipset */ addq $4, %rax /* increment skipset pointer */ movb %cl, (%rsp,%rcx) /* set corresponding byte in skipset table */ testb %cl, %cl /* is NUL char? */ jnz L(2) /* no => process next dword from skipset */ L(1): leaq -4(%rdx), %rax /* 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 skipset was found and 2. the end of the string was found But as a sign that the character is in the skipset we store its value in the table. But the value of NUL is NUL so the loop terminates for NUL in every case. */ /* Next 3 insns are 9 bytes total. */ /* .p2align 4,,9 would make sure we decode them in one go, */ /* but it will also align entire function to 16 bytes, */ /* potentially creating largish padding at link time. */ /* We are aligning to 8 bytes instead: */ .p2align 3,,8 L(3): addq $4, %rax /* adjust pointer for full loop round */ movb (%rax), %cl /* get byte from string */ cmpb %cl, (%rsp,%rcx) /* is it contained in skipset? */ je L(4) /* yes => return */ movb 1(%rax), %cl /* get byte from string */ cmpb %cl, (%rsp,%rcx) /* is it contained in skipset? */ je L(5) /* yes => return */ movb 2(%rax), %cl /* get byte from string */ cmpb %cl, (%rsp,%rcx) /* is it contained in skipset? */ jz L(6) /* yes => return */ movb 3(%rax), %cl /* get byte from string */ cmpb %cl, (%rsp,%rcx) /* is it contained in skipset? */ jne L(3) /* no => start loop again */ incq %rax /* adjust pointer */ L(6): incq %rax L(5): incq %rax L(4): addq $256, %rsp /* remove skipset */ #if STRPBRK_P xorl %edx,%edx orb %cl, %cl /* was last character NUL? */ cmovzq %rdx, %rax /* Yes: return NULL */ #else subq %rdx, %rax /* we have to return the number of valid characters, so compute distance to first non-valid character */ #endif ret END (strcspn) #if !STRPBRK_P libc_hidden_def(strcspn) #endif