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/*
FUNCTION
<<memset>>---set an area of memory
INDEX
memset
ANSI_SYNOPSIS
#include <string.h>
void *memset(const void *<[dst]>, int <[c]>, size_t <[length]>);
TRAD_SYNOPSIS
#include <string.h>
void *memset(<[dst]>, <[c]>, <[length]>)
void *<[dst]>;
int <[c]>;
size_t <[length]>;
DESCRIPTION
This function converts the argument <[c]> into an unsigned
char and fills the first <[length]> characters of the array
pointed to by <[dst]> to the value.
RETURNS
<<memset>> returns the value of <[m]>.
PORTABILITY
<<memset>> is ANSI C.
<<memset>> requires no supporting OS subroutines.
QUICKREF
memset ansi pure
*/
#include <string.h>
#define LBLOCKSIZE (sizeof(long))
#define UNALIGNED(X) ((long)X & (LBLOCKSIZE - 1))
#define TOO_SMALL(LEN) ((LEN) < LBLOCKSIZE)
_PTR
_DEFUN (memset, (m, c, n),
_PTR m _AND
int c _AND
size_t n)
{
#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
char *s = (char *) m;
while (n-- != 0)
{
*s++ = (char) c;
}
return m;
#else
char *s = (char *) m;
unsigned int i;
unsigned long buffer;
unsigned long *aligned_addr;
if (!TOO_SMALL (n) && !UNALIGNED (m))
{
/* If we get this far, we know that n is large and m is word-aligned. */
aligned_addr = (unsigned long*)m;
/* Store C into each char sized location in BUFFER so that
we can set large blocks quickly. */
c &= 0xff;
if (LBLOCKSIZE == 4)
{
buffer = (c << 8) | c;
buffer |= (buffer << 16);
}
else
{
buffer = 0;
for (i = 0; i < LBLOCKSIZE; i++)
buffer = (buffer << 8) | c;
}
while (n >= LBLOCKSIZE*4)
{
*aligned_addr++ = buffer;
*aligned_addr++ = buffer;
*aligned_addr++ = buffer;
*aligned_addr++ = buffer;
n -= 4*LBLOCKSIZE;
}
while (n >= LBLOCKSIZE)
{
*aligned_addr++ = buffer;
n -= LBLOCKSIZE;
}
/* Pick up the remainder with a bytewise loop. */
s = (char*)aligned_addr;
}
while (n--)
{
*s++ = (char)c;
}
return m;
#endif /* not PREFER_SIZE_OVER_SPEED */
}
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