1 /* Search character in UTF-8 string. 2 Copyright (C) 1999, 2002, 2006-2007, 2009-2021 Free Software Foundation, 3 Inc. 4 Written by Bruno Haible <bruno@clisp.org>, 2002. 5 6 This file is free software. 7 It is dual-licensed under "the GNU LGPLv3+ or the GNU GPLv2+". 8 You can redistribute it and/or modify it under either 9 - the terms of the GNU Lesser General Public License as published 10 by the Free Software Foundation; either version 3, or (at your 11 option) any later version, or 12 - the terms of the GNU General Public License as published by the 13 Free Software Foundation; either version 2, or (at your option) 14 any later version, or 15 - the same dual license "the GNU LGPLv3+ or the GNU GPLv2+". 16 17 This file is distributed in the hope that it will be useful, 18 but WITHOUT ANY WARRANTY; without even the implied warranty of 19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 20 Lesser General Public License and the GNU General Public License 21 for more details. 22 23 You should have received a copy of the GNU Lesser General Public 24 License and of the GNU General Public License along with this 25 program. If not, see <https://www.gnu.org/licenses/>. */ 26 27 #include <config.h> 28 29 /* Specification. */ 30 #include "unistr.h" 31 32 uint8_t * 33 u8_strrchr (const uint8_t *s, ucs4_t uc) /* */ 34 { 35 /* Calling u8_strlen and then searching from the other end would cause more 36 memory accesses. Avoid that, at the cost of a few more comparisons. */ 37 uint8_t *result = NULL; 38 uint8_t c[6]; 39 40 if (uc < 0x80) 41 { 42 uint8_t c0 = uc; 43 44 for (;; s++) 45 { 46 if (*s == c0) 47 result = (uint8_t *) s; 48 if (*s == 0) 49 break; 50 } 51 } 52 else 53 switch (u8_uctomb_aux (c, uc, 6)) 54 { 55 case 2: 56 if (*s) 57 { 58 uint8_t c0 = c[0]; 59 uint8_t c1 = c[1]; 60 61 /* FIXME: Maybe walking the string via u8_mblen is a win? */ 62 for (;; s++) 63 { 64 if (s[1] == 0) 65 break; 66 if (*s == c0 && s[1] == c1) 67 result = (uint8_t *) s; 68 } 69 } 70 break; 71 72 case 3: 73 if (*s && s[1]) 74 { 75 uint8_t c0 = c[0]; 76 uint8_t c1 = c[1]; 77 uint8_t c2 = c[2]; 78 79 /* FIXME: Maybe walking the string via u8_mblen is a win? */ 80 for (;; s++) 81 { 82 if (s[2] == 0) 83 break; 84 if (*s == c0 && s[1] == c1 && s[2] == c2) 85 result = (uint8_t *) s; 86 } 87 } 88 break; 89 90 case 4: 91 if (*s && s[1] && s[2]) 92 { 93 uint8_t c0 = c[0]; 94 uint8_t c1 = c[1]; 95 uint8_t c2 = c[2]; 96 uint8_t c3 = c[3]; 97 98 /* FIXME: Maybe walking the string via u8_mblen is a win? */ 99 for (;; s++) 100 { 101 if (s[3] == 0) 102 break; 103 if (*s == c0 && s[1] == c1 && s[2] == c2 && s[3] == c3) 104 result = (uint8_t *) s; 105 } 106 } 107 break; 108 } 109 return result; 110 }