xv6-65oo2/kernel/string.c

108 lines
1.4 KiB
C
Raw Normal View History

2006-06-15 16:02:20 +00:00
#include "types.h"
2006-09-06 17:27:19 +00:00
void*
memset(void *dst, int c, uint n)
2006-06-12 15:22:12 +00:00
{
2019-05-31 13:45:59 +00:00
char *cdst = (char *) dst;
int i;
for(i = 0; i < n; i++){
cdst[i] = c;
}
2006-06-12 15:22:12 +00:00
return dst;
}
2006-06-21 01:53:07 +00:00
int
memcmp(const void *v1, const void *v2, uint n)
2006-06-21 01:53:07 +00:00
{
2007-08-10 17:17:42 +00:00
const uchar *s1, *s2;
2007-08-10 17:17:42 +00:00
s1 = v1;
s2 = v2;
2007-08-28 18:32:08 +00:00
while(n-- > 0){
2006-09-06 17:27:19 +00:00
if(*s1 != *s2)
2007-08-10 17:17:42 +00:00
return *s1 - *s2;
2006-06-21 01:53:07 +00:00
s1++, s2++;
}
return 0;
}
2006-09-06 17:27:19 +00:00
void*
memmove(void *dst, const void *src, uint n)
{
const char *s;
char *d;
if(n == 0)
return dst;
s = src;
d = dst;
2007-08-28 18:32:08 +00:00
if(s < d && s + n > d){
s += n;
d += n;
2006-09-06 17:27:19 +00:00
while(n-- > 0)
*--d = *--s;
2007-08-28 18:37:41 +00:00
} else
2006-09-06 17:27:19 +00:00
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)
{
2006-09-06 17:27:19 +00:00
while(n > 0 && *p && *p == *q)
n--, p++, q++;
2006-09-06 17:27:19 +00:00
if(n == 0)
return 0;
2007-08-24 21:00:02 +00:00
return (uchar)*p - (uchar)*q;
}
char*
strncpy(char *s, const char *t, int n)
{
char *os;
2007-08-24 21:00:02 +00:00
os = s;
while(n-- > 0 && (*s++ = *t++) != 0)
;
while(n-- > 0)
*s++ = 0;
return os;
}
2007-08-08 08:37:22 +00:00
// Like strncpy but guaranteed to NUL-terminate.
char*
safestrcpy(char *s, const char *t, int n)
{
char *os;
2007-08-08 08:37:22 +00:00
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;
}