0,0 → 1,102 |
/* |
FUNCTION |
<<memset>>---set an area of memory |
|
INDEX |
memset |
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ANSI_SYNOPSIS |
#include <string.h> |
void *memset(void *<[dst]>, int <[c]>, size_t <[length]>); |
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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. |
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RETURNS |
<<memset>> returns the value of <[dst]>. |
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PORTABILITY |
<<memset>> is ANSI C. |
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<<memset>> requires no supporting OS subroutines. |
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QUICKREF |
memset ansi pure |
*/ |
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#include <string.h> |
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#define LBLOCKSIZE (sizeof(long)) |
#define UNALIGNED(X) ((long)X & (LBLOCKSIZE - 1)) |
#define TOO_SMALL(LEN) ((LEN) < LBLOCKSIZE) |
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_PTR |
_DEFUN (memset, (m, c, n), |
_PTR m _AND |
int c _AND |
size_t n) |
{ |
char *s = (char *) m; |
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#if !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__) |
int i; |
unsigned long buffer; |
unsigned long *aligned_addr; |
unsigned int d = c & 0xff; /* To avoid sign extension, copy C to an |
unsigned variable. */ |
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while (UNALIGNED (s)) |
{ |
if (n--) |
*s++ = (char) c; |
else |
return m; |
} |
|
if (!TOO_SMALL (n)) |
{ |
/* If we get this far, we know that n is large and s is word-aligned. */ |
aligned_addr = (unsigned long *) s; |
|
/* Store D into each char sized location in BUFFER so that |
we can set large blocks quickly. */ |
buffer = (d << 8) | d; |
buffer |= (buffer << 16); |
for (i = 32; i < LBLOCKSIZE * 8; i <<= 1) |
buffer = (buffer << i) | buffer; |
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/* Unroll the loop. */ |
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; |
} |
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#endif /* not PREFER_SIZE_OVER_SPEED */ |
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while (n--) |
*s++ = (char) c; |
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return m; |
} |