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#include <stdio.h>
inline char * my_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;
}
inline char * my_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;
}
inline char * my_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;
}
inline char * my_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;
}
inline int my_strcmp(const char * cs,const char * ct)
{
int d0, d1;
register 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;
}
inline int my_strncmp(const char * cs,const char * ct,size_t count)
{
register 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;
}
inline char* my_strchr(const char * s, int c)
{
int d0;
register 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;
}
inline char* my_strrchr(const char * s, int c)
{
int d0, d1;
register char * __res;
__asm__ __volatile__(
"movb %%al,%%ah\n"
"1:\tlodsb\n\t"
"cmpb %%ah,%%al\n\t"
"jne 2f\n\t"
"leal -1(%%esi),%0\n"
"2:\ttestb %%al,%%al\n\t"
"jne 1b"
:"=g" (__res), "=&S" (d0), "=&a" (d1)
:"0" (0),"1" (s),"2" (c)
:"memory");
return __res;
}
inline int my_strlen(const char * s)
{
int d0;
register 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;
}
inline void* my_memcpy(void * to, const void * from, size_t n)
{
int d0, d1, d2;
__asm__ __volatile__(
"rep ; movsl\n\t"
"movl %4,%%ecx\n\t"
"andl $3,%%ecx\n\t"
#if 1 /* want to pay 2 byte penalty for a chance to skip microcoded rep? */
"jz 1f\n\t"
#endif
"rep ; movsb\n\t"
"1:"
: "=&c" (d0), "=&D" (d1), "=&S" (d2)
: "0" (n/4), "g" (n), "1" ((long) to), "2" ((long) from)
: "memory");
return (to);
}
int main()
{
char string[50];
char* str1 = "Hello world\n";
char* str2 = "Hello jimmy\n";
my_strcpy(string,str1);
printf("string is %s after my_strcpy str1 %s\n",string,str1);
my_strncpy(string,str1,11);
printf("string is %s after my_strcpy str1 %s len 10\n",string,str1);
my_strcat(string,str2);
printf("string is %s after my_strcat str2 %s\n",string,str2);
my_strncat(string,str1,5);
printf("string is %s after my_strcpy str1 %s len 5\n",string,str1);
printf("str1 %s compare str2 %s is %d\n",str1,str2,my_strcmp(str1,str2));
printf("str1 %s compare str2 %s len 5 is %d\n",str1,str2,my_strncmp(str1,str2,5));
printf("strchr str1 %s char 'o' is %s\n",str1,my_strchr(str1,'o'));
printf("strrchr str1 %s char 'o' is %s\n",str1,my_strrchr(str1,'o'));
printf("strlen str1 %s is %d\n",str1,my_strlen(str1));
my_memcpy(string,str1,11);
printf("string is %s after my_memcpy str1 %s\n",string,str1);
return 0;
}
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