// 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. */ #define __NO_FORTIFY#include <linux/string.h>#include <linux/export.h> #ifdef __HAVE_ARCH_STRCPYchar *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_STRCATchar *strcat(char *dest, const char *src){	int d0, d1, d2, d3;	asm volatile("repne 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_STRNCATchar *strncat(char *dest, const char *src, size_t count){	int d0, d1, d2, d3;	asm volatile("repne 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_STRCMPint 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_STRNCMPint 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_STRCHRchar *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_STRLENsize_t strlen(const char *s){	int d0;	size_t res;	asm volatile("repne scasb"		: "=c" (res), "=&D" (d0)		: "1" (s), "a" (0), "0" (0xffffffffu)		: "memory");	return ~res - 1;}EXPORT_SYMBOL(strlen);#endif #ifdef __HAVE_ARCH_MEMCHRvoid *memchr(const void *cs, int c, size_t count){	int d0;	void *res;	if (!count)		return NULL;	asm volatile("repne 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_MEMSCANvoid *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_STRNLENsize_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