/* * Most of the string-functions are rather heavily hand-optimized, * see especially strsep,strstr,str[c]spn. They should work, but are not * very easy to understand. Everything is done entirely within the register * set, making the functions fast and clean. String instructions have been * used through-out, making for "slightly" unclear code :-) * * AK: On P4 and K7 using non string instruction implementations might be faster * for large memory blocks. But most of them are unlikely to be used on large * strings. */ #include <linux/string.h> #include <linux/module.h> #ifdef __HAVE_ARCH_STRCPY char *strcpy(char *dest, const char *src) { int d0, d1, d2; asm volatile("1:\tlodsb\n\t" "stosb\n\t" "testb %%al,%%al\n\t" "jne 1b" : "=&S" (d0), "=&D" (d1), "=&a" (d2) : "0" (src), "1" (dest) : "memory"); return dest; } EXPORT_SYMBOL(strcpy); #endif #ifdef __HAVE_ARCH_STRNCPY char *strncpy(char *dest, const char *src, size_t count) { int d0, d1, d2, d3; asm volatile("1:\tdecl %2\n\t" "js 2f\n\t" "lodsb\n\t" "stosb\n\t" "testb %%al,%%al\n\t" "jne 1b\n\t" "rep\n\t" "stosb\n" "2:" : "=&S" (d0), "=&D" (d1), "=&c" (d2), "=&a" (d3) : "0" (src), "1" (dest), "2" (count) : "memory"); return dest; } EXPORT_SYMBOL(strncpy); #endif #ifdef __HAVE_ARCH_STRCAT char *strcat(char *dest, const char *src) { int d0, d1, d2, d3; asm volatile("repne\n\t" "scasb\n\t" "decl %1\n" "1:\tlodsb\n\t" "stosb\n\t" "testb %%al,%%al\n\t" "jne 1b" : "=&S" (d0), "=&D" (d1), "=&a" (d2), "=&c" (d3) : "0" (src), "1" (dest), "2" (0), "3" (0xffffffffu) : "memory"); return dest; } EXPORT_SYMBOL(strcat); #endif #ifdef __HAVE_ARCH_STRNCAT char *strncat(char *dest, const char *src, size_t count) { int d0, d1, d2, d3; asm volatile("repne\n\t" "scasb\n\t" "decl %1\n\t" "movl %8,%3\n" "1:\tdecl %3\n\t" "js 2f\n\t" "lodsb\n\t" "stosb\n\t" "testb %%al,%%al\n\t" "jne 1b\n" "2:\txorl %2,%2\n\t" "stosb" : "=&S" (d0), "=&D" (d1), "=&a" (d2), "=&c" (d3) : "0" (src), "1" (dest), "2" (0), "3" (0xffffffffu), "g" (count) : "memory"); return dest; } EXPORT_SYMBOL(strncat); #endif #ifdef __HAVE_ARCH_STRCMP int strcmp(const char *cs, const char *ct) { int d0, d1; int res; asm volatile("1:\tlodsb\n\t" "scasb\n\t" "jne 2f\n\t" "testb %%al,%%al\n\t" "jne 1b\n\t" "xorl %%eax,%%eax\n\t" "jmp 3f\n" "2:\tsbbl %%eax,%%eax\n\t" "orb $1,%%al\n" "3:" : "=a" (res), "=&S" (d0), "=&D" (d1) : "1" (cs), "2" (ct) : "memory"); return res; } EXPORT_SYMBOL(strcmp); #endif #ifdef __HAVE_ARCH_STRNCMP int strncmp(const char *cs, const char *ct, size_t count) { int res; int d0, d1, d2; asm volatile("1:\tdecl %3\n\t" "js 2f\n\t" "lodsb\n\t" "scasb\n\t" "jne 3f\n\t" "testb %%al,%%al\n\t" "jne 1b\n" "2:\txorl %%eax,%%eax\n\t" "jmp 4f\n" "3:\tsbbl %%eax,%%eax\n\t" "orb $1,%%al\n" "4:" : "=a" (res), "=&S" (d0), "=&D" (d1), "=&c" (d2) : "1" (cs), "2" (ct), "3" (count) : "memory"); return res; } EXPORT_SYMBOL(strncmp); #endif #ifdef __HAVE_ARCH_STRCHR char *strchr(const char *s, int c) { int d0; char *res; asm volatile("movb %%al,%%ah\n" "1:\tlodsb\n\t" "cmpb %%ah,%%al\n\t" "je 2f\n\t" "testb %%al,%%al\n\t" "jne 1b\n\t" "movl $1,%1\n" "2:\tmovl %1,%0\n\t" "decl %0" : "=a" (res), "=&S" (d0) : "1" (s), "0" (c) : "memory"); return res; } EXPORT_SYMBOL(strchr); #endif #ifdef __HAVE_ARCH_STRLEN size_t strlen(const char *s) { int d0; int res; asm volatile("repne\n\t" "scasb\n\t" "notl %0\n\t" "decl %0" : "=c" (res), "=&D" (d0) : "1" (s), "a" (0), "0" (0xffffffffu) : "memory"); return res; } EXPORT_SYMBOL(strlen); #endif #ifdef __HAVE_ARCH_MEMCHR void *memchr(const void *cs, int c, size_t count) { int d0; void *res; if (!count) return NULL; asm volatile("repne\n\t" "scasb\n\t" "je 1f\n\t" "movl $1,%0\n" "1:\tdecl %0" : "=D" (res), "=&c" (d0) : "a" (c), "0" (cs), "1" (count) : "memory"); return res; } EXPORT_SYMBOL(memchr); #endif #ifdef __HAVE_ARCH_MEMSCAN void *memscan(void *addr, int c, size_t size) { if (!size) return addr; asm volatile("repnz; scasb\n\t" "jnz 1f\n\t" "dec %%edi\n" "1:" : "=D" (addr), "=c" (size) : "0" (addr), "1" (size), "a" (c) : "memory"); return addr; } EXPORT_SYMBOL(memscan); #endif #ifdef __HAVE_ARCH_STRNLEN size_t strnlen(const char *s, size_t count) { int d0; int res; asm volatile("movl %2,%0\n\t" "jmp 2f\n" "1:\tcmpb $0,(%0)\n\t" "je 3f\n\t" "incl %0\n" "2:\tdecl %1\n\t" "cmpl $-1,%1\n\t" "jne 1b\n" "3:\tsubl %2,%0" : "=a" (res), "=&d" (d0) : "c" (s), "1" (count) : "memory"); return res; } EXPORT_SYMBOL(strnlen); #endif