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#include <assert.h>
#include <shared/mem.h>
#include <stdint.h>
union dualptr_const { const uintptr_t *w; const char *c; uintptr_t u; };
union dualptr { uintptr_t *w; char *c; uintptr_t u; };
void *memchr(const void *s, int c, size_t n) {
const unsigned char *s2 = s;
for (size_t i = 0; i < n; i++) {
if (s2[i] == (unsigned char)c)
return (void*)&s2[i];
}
return NULL;
}
int memcmp(const void *s1, const void *s2, size_t n) {
const unsigned char *c1 = s1, *c2 = s2;
for (size_t i = 0; i < n; i++) {
if (c1[i] != c2[i]) {
if (c1[i] < c2[i]) return -1;
else return 1;
}
}
return 0;
}
void *memcpy(void *dest, const void *src, size_t n) {
// TODO erms, rep movsb
union dualptr_const s = {.c = src};
union dualptr d = {.c = dest};
if (dest == src) return dest;
// assert(src >= dest || src + n < dest);
for (; (d.u & 7) && n != 0; n--) {
*(d.c)++ = *(s.c)++;
}
while (n >= sizeof(uintptr_t)) {
*(d.w)++ = *(s.w)++;
n -= sizeof(uintptr_t);
}
while (n-- != 0) {
*(d.c)++ = *(s.c)++;
}
return dest;
}
void *memmove(void *dest, const void *src, size_t n) {
if (src >= dest || src + n < dest)
return memcpy(dest, src, n);
for (; n; n--) /* naive reverse copy */
((uint8_t*)dest)[n-1] = ((uint8_t*)src)[n-1];
return dest;
}
void *memset(void *s, int c, size_t n) {
union dualptr d = {.c = s};
uintptr_t fill = (c & 0xff) * 0x0101010101010101;
while (n >= sizeof(uintptr_t)) {
*(d.w)++ = fill;
n -= sizeof(uintptr_t);
}
while (n-- != 0)
*(d.c)++ = c;
return s;
}
int strcmp(const char *s1, const char *s2) {
while (*s1 && *s1 == *s2) {
s1++; s2++;
}
if (*s1 == *s2) return 0;
if (*s1 < *s2) return -1;
else return 1;
}
size_t strlen(const char *s) {
size_t c = 0;
while (*s++) c++;
return c;
}
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