xv6-65oo2/string.c
rsc 856e1fc1ad Attempt to clean up newproc somewhat.
Also remove all calls to memcpy in favor of
memmove, which has defined semantics when
the ranges overlap.  The fact that memcpy was
working in console.c to scroll the screen is not
guaranteed by all implementations.
2006-07-16 01:47:40 +00:00

78 lines
1.2 KiB
C

#include "types.h"
#include "defs.h"
void *
memset(void *dst, int c, unsigned n)
{
char *d = (char *) dst;
while(n-- > 0)
*d++ = c;
return dst;
}
int
memcmp(const void *v1, const void *v2, unsigned n)
{
const uint8_t *s1 = (const uint8_t *) v1;
const uint8_t *s2 = (const uint8_t *) v2;
while (n-- > 0) {
if (*s1 != *s2)
return (int) *s1 - (int) *s2;
s1++, s2++;
}
return 0;
}
void *
memmove(void *dst, const void *src, unsigned 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, unsigned n)
{
while (n > 0 && *p && *p == *q)
n--, p++, q++;
if (n == 0)
return 0;
else
return (int) ((unsigned char) *p - (unsigned char) *q);
}
// Memcpy is deprecated and should NOT be called.
// Use memmove instead, which has defined semantics
// when the two memory ranges overlap.
// Memcpy is here only because gcc compiles some
// structure assignments into calls to memcpy.
void *
memcpy(void *dst, void *src, unsigned n)
{
char *d = (char *) dst;
char *s = (char *) src;
while(n-- > 0)
*d++ = *s++;
return dst;
}