xv6-riscv-rust/kernel/string.c

91 lines
1.3 KiB
C

#include "types.h"
void *memset(void *dst, int c, uint n) {
char *cdst = (char *)dst;
int i;
for (i = 0; i < n; i++) {
cdst[i] = c;
}
return dst;
}
int memcmp(const void *v1, const void *v2, uint n) {
const uchar *s1, *s2;
s1 = v1;
s2 = v2;
while (n-- > 0) {
if (*s1 != *s2)
return *s1 - *s2;
s1++, s2++;
}
return 0;
}
void *memmove(void *dst, const void *src, uint n) {
const char *s;
char *d;
if (n == 0)
return dst;
s = src;
d = dst;
if (s < d && s + n > d) {
s += n;
d += n;
while (n-- > 0)
*--d = *--s;
} else
while (n-- > 0)
*d++ = *s++;
return dst;
}
// memcpy exists to placate GCC. Use memmove.
void *memcpy(void *dst, const void *src, uint n) {
return memmove(dst, src, n);
}
int strncmp(const char *p, const char *q, uint n) {
while (n > 0 && *p && *p == *q)
n--, p++, q++;
if (n == 0)
return 0;
return (uchar)*p - (uchar)*q;
}
char *strncpy(char *s, const char *t, int n) {
char *os;
os = s;
while (n-- > 0 && (*s++ = *t++) != 0)
;
while (n-- > 0)
*s++ = 0;
return os;
}
// Like strncpy but guaranteed to NUL-terminate.
char *safestrcpy(char *s, const char *t, int n) {
char *os;
os = s;
if (n <= 0)
return os;
while (--n > 0 && (*s++ = *t++) != 0)
;
*s = 0;
return os;
}
int strlen(const char *s) {
int n;
for (n = 0; s[n]; n++)
;
return n;
}