projects / thirdparty / glibc.git / blame
| Commit | Line | Data |
|---|---|---|
| 78df0fcb AJ |
1 | /* strcspn (str, ss) -- Return the length of the initial segment of STR |
| 2 | which contains no characters from SS. | |
| 3 | For AMD x86-64. | |
| 581c785b | 4 | Copyright (C) 1994-2022 Free Software Foundation, Inc. |
| 78df0fcb | 5 | This file is part of the GNU C Library. |
| 78df0fcb AJ |
6 | |
| 7 | The GNU C Library is free software; you can redistribute it and/or | |
| 8 | modify it under the terms of the GNU Lesser General Public | |
| 9 | License as published by the Free Software Foundation; either | |
| 10 | version 2.1 of the License, or (at your option) any later version. | |
| 11 | ||
| 12 | The GNU C Library is distributed in the hope that it will be useful, | |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 15 | Lesser General Public License for more details. | |
| 16 | ||
| 17 | You should have received a copy of the GNU Lesser General Public | |
| 59ba27a6 | 18 | License along with the GNU C Library; if not, see |
| 5a82c748 | 19 | <https://www.gnu.org/licenses/>. */ |
| 78df0fcb AJ |
20 | |
| 21 | #include <sysdep.h> | |
| 22 | #include "asm-syntax.h" | |
| 23 | ||
| 78df0fcb AJ |
24 | .text |
| 25 | ENTRY (strcspn) | |
| 26 | ||
| 27 | movq %rdi, %rdx /* Save SRC. */ | |
| 28 | ||
| 29 | /* First we create a table with flags for all possible characters. | |
| 30 | For the ASCII (7bit/8bit) or ISO-8859-X character sets which are | |
| 31 | supported by the C string functions we have 256 characters. | |
| 32 | Before inserting marks for the stop characters we clear the whole | |
| 33 | table. */ | |
| 34 | movq %rdi, %r8 /* Save value. */ | |
| 35 | subq $256, %rsp /* Make space for 256 bytes. */ | |
| a5ee0b9e | 36 | cfi_adjust_cfa_offset(256) |
| ee618985 | 37 | movl $32, %ecx /* 32*8 bytes = 256 bytes. */ |
| 78df0fcb | 38 | movq %rsp, %rdi |
| ee618985 | 39 | xorl %eax, %eax /* We store 0s. */ |
| 78df0fcb AJ |
40 | cld |
| 41 | rep | |
| 42 | stosq | |
| 43 | ||
| 44 | movq %rsi, %rax /* Setup skipset. */ | |
| 45 | ||
| 46 | /* For understanding the following code remember that %rcx == 0 now. | |
| 47 | Although all the following instruction only modify %cl we always | |
| 48 | have a correct zero-extended 64-bit value in %rcx. */ | |
| 49 | ||
| 50 | .p2align 4 | |
| 51 | L(2): movb (%rax), %cl /* get byte from skipset */ | |
| 52 | testb %cl, %cl /* is NUL char? */ | |
| 53 | jz L(1) /* yes => start compare loop */ | |
| 54 | movb %cl, (%rsp,%rcx) /* set corresponding byte in skipset table */ | |
| 55 | ||
| 56 | movb 1(%rax), %cl /* get byte from skipset */ | |
| 57 | testb $0xff, %cl /* is NUL char? */ | |
| 58 | jz L(1) /* yes => start compare loop */ | |
| 59 | movb %cl, (%rsp,%rcx) /* set corresponding byte in skipset table */ | |
| 60 | ||
| 61 | movb 2(%rax), %cl /* get byte from skipset */ | |
| 62 | testb $0xff, %cl /* is NUL char? */ | |
| 63 | jz L(1) /* yes => start compare loop */ | |
| 64 | movb %cl, (%rsp,%rcx) /* set corresponding byte in skipset table */ | |
| 65 | ||
| 66 | movb 3(%rax), %cl /* get byte from skipset */ | |
| 67 | addq $4, %rax /* increment skipset pointer */ | |
| 68 | movb %cl, (%rsp,%rcx) /* set corresponding byte in skipset table */ | |
| 69 | testb $0xff, %cl /* is NUL char? */ | |
| 70 | jnz L(2) /* no => process next dword from skipset */ | |
| 71 | ||
| 72 | L(1): leaq -4(%rdx), %rax /* prepare loop */ | |
| 73 | ||
| 74 | /* We use a neat trick for the following loop. Normally we would | |
| 75 | have to test for two termination conditions | |
| 76 | 1. a character in the skipset was found | |
| 77 | and | |
| 78 | 2. the end of the string was found | |
| 79 | But as a sign that the character is in the skipset we store its | |
| 80 | value in the table. But the value of NUL is NUL so the loop | |
| 81 | terminates for NUL in every case. */ | |
| 82 | ||
| 83 | .p2align 4 | |
| 84 | L(3): addq $4, %rax /* adjust pointer for full loop round */ | |
| 85 | ||
| 86 | movb (%rax), %cl /* get byte from string */ | |
| 87 | cmpb %cl, (%rsp,%rcx) /* is it contained in skipset? */ | |
| 88 | je L(4) /* yes => return */ | |
| 89 | ||
| 90 | movb 1(%rax), %cl /* get byte from string */ | |
| 91 | cmpb %cl, (%rsp,%rcx) /* is it contained in skipset? */ | |
| 92 | je L(5) /* yes => return */ | |
| 93 | ||
| 94 | movb 2(%rax), %cl /* get byte from string */ | |
| 95 | cmpb %cl, (%rsp,%rcx) /* is it contained in skipset? */ | |
| 96 | jz L(6) /* yes => return */ | |
| 97 | ||
| 98 | movb 3(%rax), %cl /* get byte from string */ | |
| 99 | cmpb %cl, (%rsp,%rcx) /* is it contained in skipset? */ | |
| 100 | jne L(3) /* no => start loop again */ | |
| 101 | ||
| 102 | incq %rax /* adjust pointer */ | |
| 103 | L(6): incq %rax | |
| 104 | L(5): incq %rax | |
| 105 | ||
| 106 | L(4): addq $256, %rsp /* remove skipset */ | |
| 0e328c85 | 107 | cfi_adjust_cfa_offset(-256) |
| 70fe2eb7 | 108 | #ifdef USE_AS_STRPBRK |
| ee618985 | 109 | xorl %edx,%edx |
| 78df0fcb AJ |
110 | orb %cl, %cl /* was last character NUL? */ |
| 111 | cmovzq %rdx, %rax /* Yes: return NULL */ | |
| 9c84384c | 112 | #else |
| 78df0fcb AJ |
113 | subq %rdx, %rax /* we have to return the number of valid |
| 114 | characters, so compute distance to first | |
| 115 | non-valid character */ | |
| 116 | #endif | |
| 117 | ret | |
| 118 | END (strcspn) | |
| 85dd1003 | 119 | libc_hidden_builtin_def (strcspn) |