1 /* 2 * Copyright (c) 2017 Imagination Technologies. 3 * 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 10 * * Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * * Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer 14 * in the documentation and/or other materials provided with 15 * the distribution. 16 * * Neither the name of Imagination Technologies nor the names of its 17 * contributors may be used to endorse or promote products derived 18 * from this software without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 21 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 23 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 24 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 25 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 26 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 30 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 #include <string.h> 34 35 #define op_t unsigned long int 36 #define op_size sizeof (op_t) 37 38 #if __mips64 || __mips_isa_rev >= 2 39 static inline size_t __attribute__ ((always_inline)) 40 do_bytes (const char *base, const char *p, op_t inval) 41 { 42 op_t outval = 0; 43 #if __mips64 44 __asm__ volatile ( 45 "dsbh %1, %0 \n\t" 46 "dshd %0, %1 \n\t" 47 "dclz %1, %0 \n\t" 48 : "+r" (inval), "+r" (outval) 49 ); 50 #else 51 __asm__ volatile ( 52 "wsbh %1, %0 \n\t" 53 "rotr %0, %1, 16 \n\t" 54 "clz %1, %0 \n\t" 55 : "+r" (inval), "+r" (outval) 56 ); 57 #endif 58 p += (outval >> 3); 59 return (size_t) (p - base); 60 } 61 62 #define DO_WORD(w, cnt) { \ 63 op_t val = ((w[cnt] - mask_1) & ~w[cnt]) & mask_128; \ 64 if (val) \ 65 return do_bytes(str, (const char *)(w + cnt), val); \ 66 } 67 #else 68 static inline size_t __attribute__ ((always_inline)) 69 do_bytes (const char *base, const char *p) 70 { 71 for (; *p; ++p); 72 return (size_t) (p - base); 73 } 74 75 #define DO_WORD(w, cnt) { \ 76 if (((w[cnt] - mask_1) & ~w[cnt]) & mask_128) \ 77 return do_bytes(str, (const char *)(w + cnt)); \ 78 } 79 #endif 80 81 size_t 82 strlen (const char *str) 83 { 84 if (*str) { 85 const char *p = (const char *) str; 86 const op_t *w; 87 op_t mask_1, mask_128; 88 89 while ((size_t) p % sizeof (op_t)) { 90 if (!(*p)) 91 return (p - str); 92 p++; 93 } 94 95 __asm__ volatile ( 96 "li %0, 0x01010101 \n\t" 97 : "=r" (mask_1) 98 ); 99 #if __mips64 100 mask_1 |= mask_1 << 32; 101 #endif 102 mask_128 = mask_1 << 7; 103 104 w = (const op_t *) p; 105 106 while (1) { 107 DO_WORD(w, 0); 108 DO_WORD(w, 1); 109 DO_WORD(w, 2); 110 DO_WORD(w, 3); 111 w += 4; 112 } 113 } 114 return 0; 115 } 116
