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#include "string.h"
#define K1 0x80808080
#define K2 0xFEFEFEFF
size_t strlen(const char* str) {
size_t len = -1;
unsigned char* p = (unsigned char*)str - 1;
do {
len++;
} while (*++p);
return len;
}
char* strcpy(char* dst, const char* src) {
register unsigned char *destb, *fromb;
register unsigned long w, t, align;
fromb = (unsigned char*)src;
destb = (unsigned char*)dst;
if ((align = ((int)fromb & 3)) != ((int)destb & 3)) {
goto bytecopy;
}
if (align) {
if ((*destb = *fromb) == 0) {
return dst;
}
for (align = 3 - align; align; align--) {
if ((*(++destb) = *(++fromb)) == 0) {
return dst;
}
}
++destb;
++fromb;
}
w = *((int*)(fromb));
t = w + K2;
t &= K1;
if (t) {
goto bytecopy;
}
--((int*)(destb));
do {
*(++((int*)(destb))) = w;
w = *(++((int*)(fromb)));
t = w + K2;
t &= K1;
if (t) {
goto adjust;
}
} while (1);
adjust:
++((int*)(destb));
bytecopy:
if ((*destb = *fromb) == 0) {
return dst;
}
do {
if ((*(++destb) = *(++fromb)) == 0) {
return dst;
}
} while (1);
return dst;
}
char* strncpy(char* dst, const char* src, size_t n) {
const unsigned char* p = (const unsigned char*)src - 1;
unsigned char* q = (unsigned char*)dst - 1;
n++;
while (--n) {
if (!(*++q = *++p)) {
while (--n) {
*++q = 0;
}
break;
}
}
return dst;
}
char* strcat(char* dst, const char* src) {
const unsigned char* p = (unsigned char*)src - 1;
unsigned char* q = (unsigned char*)dst - 1;
while (*++q) {
}
q--;
while (*++q = *++p) {
}
return dst;
}
int strcmp(const char* str1, const char* str2) {
register unsigned char* left = (unsigned char*)str1;
register unsigned char* right = (unsigned char*)str2;
unsigned long align, l1, r1, x;
l1 = *left;
r1 = *right;
if (l1 - r1) {
return l1 - r1;
}
if ((align = ((int)left & 3)) != ((int)right & 3)) {
goto bytecopy;
}
if (align) {
if (l1 == 0) {
return 0;
}
for (align = 3 - align; align; align--) {
l1 = *(++left);
r1 = *(++right);
if (l1 - r1) {
return l1 - r1;
}
if (l1 == 0) {
return 0;
}
}
left++;
right++;
}
l1 = *(int*)left;
r1 = *(int*)right;
x = l1 + K2;
if (x & K1) {
goto adjust;
}
while (l1 == r1) {
l1 = *(++((int*)(left)));
r1 = *(++((int*)(right)));
x = l1 + K2;
if (x & K1) {
goto adjust;
}
}
if (l1 > r1) {
return 1;
}
return -1;
adjust:
l1 = *left;
r1 = *right;
if (l1 - r1) {
return l1 - r1;
}
bytecopy:
if (l1 == 0) {
return 0;
}
do {
l1 = *(++left);
r1 = *(++right);
if (l1 - r1) {
return l1 - r1;
}
if (l1 == 0) {
return 0;
}
} while (1);
}
int strncmp(const char* str1, const char* str2, size_t n) {
const unsigned char* p1 = (unsigned char*)str1 - 1;
const unsigned char* p2 = (unsigned char*)str2 - 1;
unsigned long c1, c2;
n++;
while (--n) {
if ((c1 = *++p1) != (c2 = *++p2)) {
return c1 - c2;
} else if (c1 == 0) {
break;
}
}
return 0;
}
char* strchr(const char* str, int c) {
const unsigned char* p = (unsigned char*)str - 1;
unsigned long chr = (c & 0xFF);
unsigned long ch;
while (ch = *++p) {
if (ch == chr) {
return (char*)p;
}
}
return chr ? NULL : (char*)p;
}
char* strrchr(const char* str, int c) {
const unsigned char* p = (unsigned char*)str - 1;
const unsigned char* q = NULL;
unsigned long chr = (c & 0xFF);
unsigned long ch;
while (ch = *++p) {
if (ch == chr) {
q = p;
}
}
if (q != NULL) {
return (char*)q;
}
return chr ? NULL : (char*)p;
}
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