1 /* strspn (str, ss) -- Return the length of the initial segment of STR
2 which contains only characters from SS.
4 Copyright (C) 1994-1997,2000,2002,2003,2004 Free Software Foundation, Inc.
5 This file is part of the GNU C Library.
6 Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>.
7 Bug fixes by Alan Modra <Alan@SPRI.Levels.UniSA.Edu.Au>.
8 Adopted for x86-64 by Andreas Jaeger <aj@suse.de>.
10 The GNU C Library is free software; you can redistribute it and/or
11 modify it under the terms of the GNU Lesser General Public
12 License as published by the Free Software Foundation; either
13 version 2.1 of the License, or (at your option) any later version.
15 The GNU C Library is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 Lesser General Public License for more details.
20 You should have received a copy of the GNU Lesser General Public
21 License along with the GNU C Library; if not, write to the Free
22 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
30 movq %rdi, %rdx /* Save SRC. */
32 /* First we create a table with flags for all possible characters.
33 For the ASCII (7bit/8bit) or ISO-8859-X character sets which are
34 supported by the C string functions we have 256 characters.
35 Before inserting marks for the stop characters we clear the whole
37 movq %rdi, %r8 /* Save value. */
38 subq $256, %rsp /* Make space for 256 bytes. */
39 cfi_adjust_cfa_offset(256)
40 movq $32, %rcx /* 32*8 bytes = 256 bytes. */
42 xorq %rax, %rax /* We store 0s. */
47 movq %rsi, %rax /* Setup stopset. */
49 /* For understanding the following code remember that %rcx == 0 now.
50 Although all the following instruction only modify %cl we always
51 have a correct zero-extended 64-bit value in %rcx. */
54 L(2): movb (%rax), %cl /* get byte from stopset */
55 testb %cl, %cl /* is NUL char? */
56 jz L(1) /* yes => start compare loop */
57 movb %cl, (%rsp,%rcx) /* set corresponding byte in stopset table */
59 movb 1(%rax), %cl /* get byte from stopset */
60 testb $0xff, %cl /* is NUL char? */
61 jz L(1) /* yes => start compare loop */
62 movb %cl, (%rsp,%rcx) /* set corresponding byte in stopset table */
64 movb 2(%rax), %cl /* get byte from stopset */
65 testb $0xff, %cl /* is NUL char? */
66 jz L(1) /* yes => start compare loop */
67 movb %cl, (%rsp,%rcx) /* set corresponding byte in stopset table */
69 movb 3(%rax), %cl /* get byte from stopset */
70 addq $4, %rax /* increment stopset pointer */
71 movb %cl, (%rsp,%rcx) /* set corresponding byte in stopset table */
72 testb $0xff, %cl /* is NUL char? */
73 jnz L(2) /* no => process next dword from stopset */
75 L(1): leaq -4(%rdx), %rax /* prepare loop */
77 /* We use a neat trick for the following loop. Normally we would
78 have to test for two termination conditions
79 1. a character in the stopset was found
81 2. the end of the string was found
82 But as a sign that the character is in the stopset we store its
83 value in the table. But the value of NUL is NUL so the loop
84 terminates for NUL in every case. */
87 L(3): addq $4, %rax /* adjust pointer for full loop round */
89 movb (%rax), %cl /* get byte from string */
90 testb %cl, (%rsp,%rcx) /* is it contained in skipset? */
91 jz L(4) /* no => return */
93 movb 1(%rax), %cl /* get byte from string */
94 testb %cl, (%rsp,%rcx) /* is it contained in skipset? */
95 jz L(5) /* no => return */
97 movb 2(%rax), %cl /* get byte from string */
98 testb %cl, (%rsp,%rcx) /* is it contained in skipset? */
99 jz L(6) /* no => return */
101 movb 3(%rax), %cl /* get byte from string */
102 testb %cl, (%rsp,%rcx) /* is it contained in skipset? */
103 jnz L(3) /* yes => start loop again */
105 incq %rax /* adjust pointer */
109 L(4): addq $256, %rsp /* remove stopset */
110 cfi_adjust_cfa_offset(-256)
111 subq %rdx, %rax /* we have to return the number of valid
112 characters, so compute distance to first
113 non-valid character */
116 libc_hidden_builtin_def (strspn)