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klibc.c
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klibc.c
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// libc routines shared between kernel space and userspace
#include "u.h"
void *
memmove(void *dst, void *src, usize n)
{
const char *s = src;
char *d = dst;
if (s < d && s+n > d) {
s += n;
d += n;
while (n--)
*--d = *--s;
} else {
while (n--)
*d++ = *s++;
}
return dst;
}
// GCC wants memcpy for *foo = *bar. We'll just use memmove.
void *
memcpy(void *dst, void *src, usize n)
{
return memmove(dst, src, n);
}
void *
memset(void *p, int c, usize n)
{
byte *cp = p;
usize i;
for (i = 0; i < n; i++) {
cp[i] = (byte)c;
}
return p;
}
void *
memzero(void *p, usize n)
{
return memset(p, 0, n);
}
int
isdigit(int c)
{
return c >= '0' && c <= '9';
}
// NOTE:
// - base is ignored
// - only supports positive numbers
long
strtol(char *s, char **endptr, int base)
{
long i = 0;
while (isdigit(*s)) {
i = i*10 + (*s - '0');
s++;
}
if (endptr) {
*endptr = s;
}
return i;
}
int
strcmp(char *s1, char *s2)
{
char *p1, *p2;
p1 = s1;
p2 = s2;
for (;;) {
if (*p1 == '\0' && *p2 == '\0')
return 0;
else if (*p1 == '\0')
return -1;
else if (*p2 == '\0')
return 1;
else if (*p1 < *p2)
return -1;
else if (*p1 > *p2)
return 1;
p1++;
p2++;
}
}
usize
strlen(char *s)
{
usize len;
for (len = 0; *s != '\0'; s++, len++)
;
return len;
}