diff options
Diffstat (limited to 'libc/string/x86_64/strspn.S')
| -rw-r--r-- | libc/string/x86_64/strspn.S | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/libc/string/x86_64/strspn.S b/libc/string/x86_64/strspn.S new file mode 100644 index 000000000..245d8e699 --- /dev/null +++ b/libc/string/x86_64/strspn.S @@ -0,0 +1,114 @@ +/* strspn (str, ss) -- Return the length of the initial segment of STR + which contains only 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, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#include "_glibc_inc.h" + + .text +ENTRY (strspn) + + 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 stopset. */ + +/* 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. */ + + .p2align 4 +L(2): movb (%rax), %cl /* get byte from stopset */ + testb %cl, %cl /* is NUL char? */ + jz L(1) /* yes => start compare loop */ + movb %cl, (%rsp,%rcx) /* set corresponding byte in stopset table */ + + movb 1(%rax), %cl /* get byte from stopset */ + testb $0xff, %cl /* is NUL char? */ + jz L(1) /* yes => start compare loop */ + movb %cl, (%rsp,%rcx) /* set corresponding byte in stopset table */ + + movb 2(%rax), %cl /* get byte from stopset */ + testb $0xff, %cl /* is NUL char? */ + jz L(1) /* yes => start compare loop */ + movb %cl, (%rsp,%rcx) /* set corresponding byte in stopset table */ + + movb 3(%rax), %cl /* get byte from stopset */ + addq $4, %rax /* increment stopset pointer */ + movb %cl, (%rsp,%rcx) /* set corresponding byte in stopset table */ + testb $0xff, %cl /* is NUL char? */ + jnz L(2) /* no => process next dword from stopset */ + +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 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. */ + + .p2align 4 +L(3): addq $4, %rax /* adjust pointer for full loop round */ + + movb (%rax), %cl /* get byte from string */ + testb %cl, (%rsp,%rcx) /* is it contained in skipset? */ + jz L(4) /* no => return */ + + movb 1(%rax), %cl /* get byte from string */ + testb %cl, (%rsp,%rcx) /* is it contained in skipset? */ + jz L(5) /* no => return */ + + movb 2(%rax), %cl /* get byte from string */ + testb %cl, (%rsp,%rcx) /* is it contained in skipset? */ + jz L(6) /* no => return */ + + movb 3(%rax), %cl /* get byte from string */ + testb %cl, (%rsp,%rcx) /* is it contained in skipset? */ + jnz L(3) /* yes => start loop again */ + + incq %rax /* adjust pointer */ +L(6): incq %rax +L(5): incq %rax + +L(4): addq $256, %rsp /* remove stopset */ + subq %rdx, %rax /* we have to return the number of valid + characters, so compute distance to first + non-valid character */ + ret +END (strspn) |