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Diffstat (limited to 'arch/x86/lib/string_32.c')
| -rw-r--r-- | arch/x86/lib/string_32.c | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/arch/x86/lib/string_32.c b/arch/x86/lib/string_32.c new file mode 100644 index 000000000..d15fdae96 --- /dev/null +++ b/arch/x86/lib/string_32.c @@ -0,0 +1,236 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * 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/export.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; + size_t res; + asm volatile("repne\n\t" + "scasb" + : "=c" (res), "=&D" (d0) + : "1" (s), "a" (0), "0" (0xffffffffu) + : "memory"); + return ~res - 1; +} +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 |