| lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame^] | 1 | /* Copyright (C) 1991, 1996, 1997, 2003 Free Software Foundation, Inc. |
| 2 | This file is part of the GNU C Library. |
| 3 | |
| 4 | The GNU C Library is free software; you can redistribute it and/or |
| 5 | modify it under the terms of the GNU Lesser General Public |
| 6 | License as published by the Free Software Foundation; either |
| 7 | version 2.1 of the License, or (at your option) any later version. |
| 8 | |
| 9 | The GNU C Library is distributed in the hope that it will be useful, |
| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | Lesser General Public License for more details. |
| 13 | |
| 14 | You should have received a copy of the GNU Lesser General Public |
| 15 | License along with the GNU C Library; if not, write to the Free |
| 16 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 17 | 02111-1307 USA. */ |
| 18 | |
| 19 | #include <string.h> |
| 20 | #include "memcopy.h" |
| 21 | |
| 22 | /* Compare no more than N characters of S1 and S2, |
| 23 | returning less than, equal to or greater than zero |
| 24 | if S1 is lexicographically less than, equal to or |
| 25 | greater than S2. */ |
| 26 | int strncmp (const char *s1, const char *s2, size_t n) |
| 27 | { |
| 28 | unsigned reg_char c1 = '\0'; |
| 29 | unsigned reg_char c2 = '\0'; |
| 30 | |
| 31 | if (n >= 4) |
| 32 | { |
| 33 | size_t n4 = n >> 2; |
| 34 | do |
| 35 | { |
| 36 | c1 = (unsigned char) *s1++; |
| 37 | c2 = (unsigned char) *s2++; |
| 38 | if (c1 == '\0' || c1 != c2) |
| 39 | return c1 - c2; |
| 40 | c1 = (unsigned char) *s1++; |
| 41 | c2 = (unsigned char) *s2++; |
| 42 | if (c1 == '\0' || c1 != c2) |
| 43 | return c1 - c2; |
| 44 | c1 = (unsigned char) *s1++; |
| 45 | c2 = (unsigned char) *s2++; |
| 46 | if (c1 == '\0' || c1 != c2) |
| 47 | return c1 - c2; |
| 48 | c1 = (unsigned char) *s1++; |
| 49 | c2 = (unsigned char) *s2++; |
| 50 | if (c1 == '\0' || c1 != c2) |
| 51 | return c1 - c2; |
| 52 | } while (--n4 > 0); |
| 53 | n &= 3; |
| 54 | } |
| 55 | |
| 56 | while (n > 0) |
| 57 | { |
| 58 | c1 = (unsigned char) *s1++; |
| 59 | c2 = (unsigned char) *s2++; |
| 60 | if (c1 == '\0' || c1 != c2) |
| 61 | return c1 - c2; |
| 62 | n--; |
| 63 | } |
| 64 | |
| 65 | return c1 - c2; |
| 66 | } |
| 67 | libc_hidden_weak(strncmp) |