xv6/string.c
2007-08-24 21:00:02 +00:00

99 lines
1.2 KiB
C

#include "types.h"
#include "defs.h"
void*
memset(void *dst, int c, uint n)
{
char *d;
d = (char*)dst;
while(n-- > 0)
*d++ = 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;
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;
}
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;
}