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 39 typedef struct 40 { 41 op_t B0:8, B1:8, B2:8, B3:8, B4:8, B5:8, B6:8, B7:8; 42 } bits_t; 43 #else 44 typedef struct 45 { 46 op_t B0:8, B1:8, B2:8, B3:8; 47 } bits_t; 48 #endif 49 50 typedef union 51 { 52 op_t v; 53 bits_t b; 54 } bitfields_t; 55 56 #define DO_BYTE(i) \ 57 if (a.b.B##i != ch) { \ 58 if(a.b.B##i == '\0') return 0; \ 59 p++; \ 60 } else \ 61 return (char *)p; 62 63 #define DO_WORD(w, cnt) { \ 64 op_t val = w[cnt] ^ mask_c; \ 65 if ((((w[cnt] - mask_1) & ~w[cnt]) & mask_128) || \ 66 (((val - mask_1) & ~val) & mask_128)) { \ 67 return do_bytes(w + cnt, ch); \ 68 } \ 69 } 70 71 static inline char * __attribute__ ((always_inline)) 72 do_bytes (const op_t* w, unsigned char ch) 73 { 74 bitfields_t a; 75 unsigned char* p = (unsigned char *) w; 76 a.v = *w; 77 #if __mips64 78 DO_BYTE(0) 79 DO_BYTE(1) 80 DO_BYTE(2) 81 DO_BYTE(3) 82 DO_BYTE(4) 83 DO_BYTE(5) 84 DO_BYTE(6) 85 DO_BYTE(7) 86 #else 87 DO_BYTE(0) 88 DO_BYTE(1) 89 DO_BYTE(2) 90 DO_BYTE(3) 91 #endif 92 return (char *)p; 93 } 94 95 char* strchr(const char* s, int c) 96 { 97 const op_t *w; 98 op_t mask_1, mask_128, mask_c; 99 const unsigned char ch = c; 100 unsigned char* p = (unsigned char *) s; 101 102 /* 103 * Check byte by byte till initial alignment 104 */ 105 for ( ; *p != ch && ((size_t) p % op_size) != 0; p++) 106 if (*p == '\0') 107 return 0; 108 109 if (*p != ch) { 110 w = (const op_t *) p; 111 112 mask_c = ch | (ch << 8); 113 mask_c |= mask_c << 16; 114 __asm__ volatile ( 115 "li %0, 0x01010101 \n\t" 116 : "=r" (mask_1) 117 ); 118 #if __mips64 119 mask_1 |= mask_1 << 32; 120 mask_c |= mask_c << 32; 121 #endif 122 mask_128 = mask_1 << 7; 123 124 /* 125 * Check word/dword wize after initial alignment till character match 126 * or end of string 127 */ 128 while (1) { 129 DO_WORD(w, 0) 130 DO_WORD(w, 1) 131 DO_WORD(w, 2) 132 DO_WORD(w, 3) 133 w += 4; 134 } 135 } 136 137 return (char *)p; 138 } 139
