projects / thirdparty / glibc.git / blame
| Commit | Line | Data |
|---|---|---|
| 78df0fcb AJ |
1 | /* strspn (str, ss) -- Return the length of the initial segment of STR |
| 2 | which contains only 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 | ||
| 23 | .text | |
| 24 | ENTRY (strspn) | |
| 25 | ||
| 26 | movq %rdi, %rdx /* Save SRC. */ | |
| 27 | ||
| 28 | /* First we create a table with flags for all possible characters. | |
| 29 | For the ASCII (7bit/8bit) or ISO-8859-X character sets which are | |
| 30 | supported by the C string functions we have 256 characters. | |
| 31 | Before inserting marks for the stop characters we clear the whole | |
| 32 | table. */ | |
| 33 | movq %rdi, %r8 /* Save value. */ | |
| 34 | subq $256, %rsp /* Make space for 256 bytes. */ | |
| 0e328c85 | 35 | cfi_adjust_cfa_offset(256) |
| ee618985 | 36 | movl $32, %ecx /* 32*8 bytes = 256 bytes. */ |
| 78df0fcb | 37 | movq %rsp, %rdi |
| ee618985 | 38 | xorl %eax, %eax /* We store 0s. */ |
| 78df0fcb AJ |
39 | cld |
| 40 | rep | |
| 41 | stosq | |
| 42 | ||
| 43 | movq %rsi, %rax /* Setup stopset. */ | |
| 44 | ||
| 45 | /* For understanding the following code remember that %rcx == 0 now. | |
| 46 | Although all the following instruction only modify %cl we always | |
| 47 | have a correct zero-extended 64-bit value in %rcx. */ | |
| 48 | ||
| 49 | .p2align 4 | |
| 50 | L(2): movb (%rax), %cl /* get byte from stopset */ | |
| 51 | testb %cl, %cl /* is NUL char? */ | |
| 52 | jz L(1) /* yes => start compare loop */ | |
| 53 | movb %cl, (%rsp,%rcx) /* set corresponding byte in stopset table */ | |
| 54 | ||
| 55 | movb 1(%rax), %cl /* get byte from stopset */ | |
| 56 | testb $0xff, %cl /* is NUL char? */ | |
| 57 | jz L(1) /* yes => start compare loop */ | |
| 58 | movb %cl, (%rsp,%rcx) /* set corresponding byte in stopset table */ | |
| 59 | ||
| 60 | movb 2(%rax), %cl /* get byte from stopset */ | |
| 61 | testb $0xff, %cl /* is NUL char? */ | |
| 62 | jz L(1) /* yes => start compare loop */ | |
| 63 | movb %cl, (%rsp,%rcx) /* set corresponding byte in stopset table */ | |
| 64 | ||
| 65 | movb 3(%rax), %cl /* get byte from stopset */ | |
| 66 | addq $4, %rax /* increment stopset pointer */ | |
| 67 | movb %cl, (%rsp,%rcx) /* set corresponding byte in stopset table */ | |
| 68 | testb $0xff, %cl /* is NUL char? */ | |
| 69 | jnz L(2) /* no => process next dword from stopset */ | |
| 70 | ||
| 71 | L(1): leaq -4(%rdx), %rax /* prepare loop */ | |
| 72 | ||
| 73 | /* We use a neat trick for the following loop. Normally we would | |
| 74 | have to test for two termination conditions | |
| 75 | 1. a character in the stopset was found | |
| 76 | and | |
| 77 | 2. the end of the string was found | |
| 78 | But as a sign that the character is in the stopset we store its | |
| 79 | value in the table. But the value of NUL is NUL so the loop | |
| 80 | terminates for NUL in every case. */ | |
| 81 | ||
| 82 | .p2align 4 | |
| 83 | L(3): addq $4, %rax /* adjust pointer for full loop round */ | |
| 84 | ||
| 85 | movb (%rax), %cl /* get byte from string */ | |
| 86 | testb %cl, (%rsp,%rcx) /* is it contained in skipset? */ | |
| 87 | jz L(4) /* no => return */ | |
| 88 | ||
| 89 | movb 1(%rax), %cl /* get byte from string */ | |
| 90 | testb %cl, (%rsp,%rcx) /* is it contained in skipset? */ | |
| 91 | jz L(5) /* no => return */ | |
| 92 | ||
| 93 | movb 2(%rax), %cl /* get byte from string */ | |
| 94 | testb %cl, (%rsp,%rcx) /* is it contained in skipset? */ | |
| 95 | jz L(6) /* no => return */ | |
| 96 | ||
| 97 | movb 3(%rax), %cl /* get byte from string */ | |
| 98 | testb %cl, (%rsp,%rcx) /* is it contained in skipset? */ | |
| 99 | jnz L(3) /* yes => start loop again */ | |
| 100 | ||
| 101 | incq %rax /* adjust pointer */ | |
| 102 | L(6): incq %rax | |
| 103 | L(5): incq %rax | |
| 104 | ||
| 105 | L(4): addq $256, %rsp /* remove stopset */ | |
| 0e328c85 | 106 | cfi_adjust_cfa_offset(-256) |
| 78df0fcb AJ |
107 | subq %rdx, %rax /* we have to return the number of valid |
| 108 | characters, so compute distance to first | |
| 109 | non-valid character */ | |
| 110 | ret | |
| 111 | END (strspn) | |
| 85dd1003 | 112 | libc_hidden_builtin_def (strspn) |