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Provide word-aligned access to memcpy(3) and memset(3)

This commit is contained in:
Xavier Del Campo Romero 2021-10-24 02:28:13 +02:00
parent 7de5b52faa
commit 282a7ff1f3
1 changed files with 55 additions and 11 deletions
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66
libpsx/src/libc/string.c
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@ -10,14 +10,40 @@
#include <unistd.h>
#include <ctype.h>
void *memcpy(void *dst, const void *src, size_t len)
void *memcpy(void *const dst, const void *const src, size_t len)
{
void *dst2 = dst;
while(len--)
*(((unsigned char*)dst++)) = *(((unsigned char*)src++));
return dst2;
union
{
const void *v;
const unsigned char *c;
const unsigned int *w;
} srcl;
union
{
void *v;
unsigned char *c;
unsigned int *w;
} dstl;
srcl.v = src;
dstl.v = dst;
/* Avoid unaligned access before doing word access. */
while (len && (((ptrdiff_t)dstl.v & (sizeof (int) - 1))
|| ((ptrdiff_t)srcl.v & (sizeof (int) - 1))))
{
*dstl.c++ = *srcl.c++;
len--;
}
for (; len >= sizeof (int); len -= sizeof (int))
*dstl.w++ = *srcl.w++;
while (len--)
*dstl.c++ = *srcl.c++;
return dst;
}
void *memccpy(void *dst, const void *src, int c, size_t len)
@ -37,11 +63,29 @@ void *memccpy(void *dst, const void *src, int c, size_t len)
void *memset(void *dst , int c , size_t len)
{
unsigned char *dstc = (unsigned char*)dst;
int x;
union
{
void *v;
unsigned char *c;
unsigned int *w;
} dstl;
for(x = 0; x < len; x++)
dstc[x] = c;
const int cw = c | c << 8 | c << 16 | c << 24;
dstl.v = dst;
/* Avoid unaligned access before doing word access. */
while (len && ((ptrdiff_t)dstl.v & (sizeof (int) - 1)))
{
*dstl.c++ = c;
len--;
}
for (; len >= sizeof (int); len -= sizeof (int))
*dstl.w++ = cw;
while (len--)
*dstl.c++ = c;
return dst;
}