1/* 2 * Most of the string-functions are rather heavily hand-optimized, 3 * see especially strsep,strstr,str[c]spn. They should work, but are not 4 * very easy to understand. Everything is done entirely within the register 5 * set, making the functions fast and clean. String instructions have been 6 * used through-out, making for "slightly" unclear code :-) 7 * 8 * AK: On P4 and K7 using non string instruction implementations might be faster 9 * for large memory blocks. But most of them are unlikely to be used on large 10 * strings. 11 */ 12 13#include <linux/string.h> 14#include <linux/module.h> 15 16#ifdef __HAVE_ARCH_STRCPY 17char *strcpy(char *dest, const char *src) 18{ 19 int d0, d1, d2; 20 asm volatile("1:\tlodsb\n\t" 21 "stosb\n\t" 22 "testb %%al,%%al\n\t" 23 "jne 1b" 24 : "=&S" (d0), "=&D" (d1), "=&a" (d2) 25 : "0" (src), "1" (dest) : "memory"); 26 return dest; 27} 28EXPORT_SYMBOL(strcpy); 29#endif 30 31#ifdef __HAVE_ARCH_STRNCPY 32char *strncpy(char *dest, const char *src, size_t count) 33{ 34 int d0, d1, d2, d3; 35 asm volatile("1:\tdecl %2\n\t" 36 "js 2f\n\t" 37 "lodsb\n\t" 38 "stosb\n\t" 39 "testb %%al,%%al\n\t" 40 "jne 1b\n\t" 41 "rep\n\t" 42 "stosb\n" 43 "2:" 44 : "=&S" (d0), "=&D" (d1), "=&c" (d2), "=&a" (d3) 45 : "0" (src), "1" (dest), "2" (count) : "memory"); 46 return dest; 47} 48EXPORT_SYMBOL(strncpy); 49#endif 50 51#ifdef __HAVE_ARCH_STRCAT 52char *strcat(char *dest, const char *src) 53{ 54 int d0, d1, d2, d3; 55 asm volatile("repne\n\t" 56 "scasb\n\t" 57 "decl %1\n" 58 "1:\tlodsb\n\t" 59 "stosb\n\t" 60 "testb %%al,%%al\n\t" 61 "jne 1b" 62 : "=&S" (d0), "=&D" (d1), "=&a" (d2), "=&c" (d3) 63 : "0" (src), "1" (dest), "2" (0), "3" (0xffffffffu) : "memory"); 64 return dest; 65} 66EXPORT_SYMBOL(strcat); 67#endif 68 69#ifdef __HAVE_ARCH_STRNCAT 70char *strncat(char *dest, const char *src, size_t count) 71{ 72 int d0, d1, d2, d3; 73 asm volatile("repne\n\t" 74 "scasb\n\t" 75 "decl %1\n\t" 76 "movl %8,%3\n" 77 "1:\tdecl %3\n\t" 78 "js 2f\n\t" 79 "lodsb\n\t" 80 "stosb\n\t" 81 "testb %%al,%%al\n\t" 82 "jne 1b\n" 83 "2:\txorl %2,%2\n\t" 84 "stosb" 85 : "=&S" (d0), "=&D" (d1), "=&a" (d2), "=&c" (d3) 86 : "0" (src), "1" (dest), "2" (0), "3" (0xffffffffu), "g" (count) 87 : "memory"); 88 return dest; 89} 90EXPORT_SYMBOL(strncat); 91#endif 92 93#ifdef __HAVE_ARCH_STRCMP 94int strcmp(const char *cs, const char *ct) 95{ 96 int d0, d1; 97 int res; 98 asm volatile("1:\tlodsb\n\t" 99 "scasb\n\t" 100 "jne 2f\n\t" 101 "testb %%al,%%al\n\t" 102 "jne 1b\n\t" 103 "xorl %%eax,%%eax\n\t" 104 "jmp 3f\n" 105 "2:\tsbbl %%eax,%%eax\n\t" 106 "orb $1,%%al\n" 107 "3:" 108 : "=a" (res), "=&S" (d0), "=&D" (d1) 109 : "1" (cs), "2" (ct) 110 : "memory"); 111 return res; 112} 113EXPORT_SYMBOL(strcmp); 114#endif 115 116#ifdef __HAVE_ARCH_STRNCMP 117int strncmp(const char *cs, const char *ct, size_t count) 118{ 119 int res; 120 int d0, d1, d2; 121 asm volatile("1:\tdecl %3\n\t" 122 "js 2f\n\t" 123 "lodsb\n\t" 124 "scasb\n\t" 125 "jne 3f\n\t" 126 "testb %%al,%%al\n\t" 127 "jne 1b\n" 128 "2:\txorl %%eax,%%eax\n\t" 129 "jmp 4f\n" 130 "3:\tsbbl %%eax,%%eax\n\t" 131 "orb $1,%%al\n" 132 "4:" 133 : "=a" (res), "=&S" (d0), "=&D" (d1), "=&c" (d2) 134 : "1" (cs), "2" (ct), "3" (count) 135 : "memory"); 136 return res; 137} 138EXPORT_SYMBOL(strncmp); 139#endif 140 141#ifdef __HAVE_ARCH_STRCHR 142char *strchr(const char *s, int c) 143{ 144 int d0; 145 char *res; 146 asm volatile("movb %%al,%%ah\n" 147 "1:\tlodsb\n\t" 148 "cmpb %%ah,%%al\n\t" 149 "je 2f\n\t" 150 "testb %%al,%%al\n\t" 151 "jne 1b\n\t" 152 "movl $1,%1\n" 153 "2:\tmovl %1,%0\n\t" 154 "decl %0" 155 : "=a" (res), "=&S" (d0) 156 : "1" (s), "0" (c) 157 : "memory"); 158 return res; 159} 160EXPORT_SYMBOL(strchr); 161#endif 162 163#ifdef __HAVE_ARCH_STRLEN 164size_t strlen(const char *s) 165{ 166 int d0; 167 int res; 168 asm volatile("repne\n\t" 169 "scasb\n\t" 170 "notl %0\n\t" 171 "decl %0" 172 : "=c" (res), "=&D" (d0) 173 : "1" (s), "a" (0), "0" (0xffffffffu) 174 : "memory"); 175 return res; 176} 177EXPORT_SYMBOL(strlen); 178#endif 179 180#ifdef __HAVE_ARCH_MEMCHR 181void *memchr(const void *cs, int c, size_t count) 182{ 183 int d0; 184 void *res; 185 if (!count) 186 return NULL; 187 asm volatile("repne\n\t" 188 "scasb\n\t" 189 "je 1f\n\t" 190 "movl $1,%0\n" 191 "1:\tdecl %0" 192 : "=D" (res), "=&c" (d0) 193 : "a" (c), "0" (cs), "1" (count) 194 : "memory"); 195 return res; 196} 197EXPORT_SYMBOL(memchr); 198#endif 199 200#ifdef __HAVE_ARCH_MEMSCAN 201void *memscan(void *addr, int c, size_t size) 202{ 203 if (!size) 204 return addr; 205 asm volatile("repnz; scasb\n\t" 206 "jnz 1f\n\t" 207 "dec %%edi\n" 208 "1:" 209 : "=D" (addr), "=c" (size) 210 : "0" (addr), "1" (size), "a" (c) 211 : "memory"); 212 return addr; 213} 214EXPORT_SYMBOL(memscan); 215#endif 216 217#ifdef __HAVE_ARCH_STRNLEN 218size_t strnlen(const char *s, size_t count) 219{ 220 int d0; 221 int res; 222 asm volatile("movl %2,%0\n\t" 223 "jmp 2f\n" 224 "1:\tcmpb $0,(%0)\n\t" 225 "je 3f\n\t" 226 "incl %0\n" 227 "2:\tdecl %1\n\t" 228 "cmpl $-1,%1\n\t" 229 "jne 1b\n" 230 "3:\tsubl %2,%0" 231 : "=a" (res), "=&d" (d0) 232 : "c" (s), "1" (count) 233 : "memory"); 234 return res; 235} 236EXPORT_SYMBOL(strnlen); 237#endif 238