/*
* Copyright (c) 2005 Martin Decky
* Copyright (c) 2018 Jiri Svoboda
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup libc
* @{
*/
/** @file
*/
#include "../include/mem.h"
#include <stdlib.h>
#include <stddef.h>
#include <stdint.h>
#include "cc.h"
#undef memset
#undef memcpy
#undef memcmp
#undef memmove
#undef memchr
/** Fill memory block with a constant value. */
DO_NOT_DISCARD
ATTRIBUTE_OPTIMIZE_NO_TLDP
void *memset(void *dest, int b, size_t n)
{
char *pb;
unsigned long *pw;
size_t word_size;
size_t n_words;
unsigned long pattern;
size_t i;
size_t fill;
/* Fill initial segment. */
word_size = sizeof(unsigned long);
fill = word_size - ((uintptr_t) dest & (word_size - 1));
if (fill > n)
fill = n;
pb = dest;
i = fill;
while (i-- != 0)
*pb++ = b;
/* Compute remaining size. */
n -= fill;
if (n == 0)
return dest;
n_words = n / word_size;
n = n % word_size;
pw = (unsigned long *) pb;
/* Create word-sized pattern for aligned segment. */
pattern = 0;
i = word_size;
while (i-- != 0)
pattern = (pattern << 8) | (uint8_t) b;
/* Fill aligned segment. */
i = n_words;
while (i-- != 0)
*pw++ = pattern;
pb = (char *) pw;
/* Fill final segment. */
i = n;
while (i-- != 0)
*pb++ = b;
return dest;
}
struct along {
unsigned long n;
} __attribute__((packed));
ATTRIBUTE_OPTIMIZE_NO_TLDP
static void *unaligned_memcpy(void *dst, const void *src, size_t n)
{
size_t i, j;
struct along *adst = dst;
const struct along *asrc = src;
for (i = 0; i < n / sizeof(unsigned long); i++)
adst[i].n = asrc[i].n;
for (j = 0; j < n % sizeof(unsigned long); j++)
((unsigned char *) (((unsigned long *) dst) + i))[j] =
((unsigned char *) (((unsigned long *) src) + i))[j];
return (char *) dst;
}
/** Copy memory block. */
DO_NOT_DISCARD
ATTRIBUTE_OPTIMIZE_NO_TLDP
void *memcpy(void *dst, const void *src, size_t n)
{
size_t i;
size_t mod, fill;
size_t word_size;
size_t n_words;
const unsigned long *srcw;
unsigned long *dstw;
const uint8_t *srcb;
uint8_t *dstb;
word_size = sizeof(unsigned long);
/*
* Are source and destination addresses congruent modulo word_size?
* If not, use unaligned_memcpy().
*/
if (((uintptr_t) dst & (word_size - 1)) !=
((uintptr_t) src & (word_size - 1)))
return unaligned_memcpy(dst, src, n);
/*
* mod is the address modulo word size. fill is the length of the
* initial buffer segment before the first word boundary.
* If the buffer is very short, use unaligned_memcpy(), too.
*/
mod = (uintptr_t) dst & (word_size - 1);
fill = word_size - mod;
if (fill > n)
fill = n;
/* Copy the initial segment. */
srcb = src;
dstb = dst;
i = fill;
while (i-- != 0)
*dstb++ = *srcb++;
/* Compute remaining length. */
n -= fill;
if (n == 0)
return dst;
/* Pointers to aligned segment. */
dstw = (unsigned long *) dstb;
srcw = (const unsigned long *) srcb;
n_words = n / word_size; /* Number of whole words to copy. */
n -= n_words * word_size; /* Remaining bytes at the end. */
/* "Fast" copy. */
i = n_words;
while (i-- != 0)
*dstw++ = *srcw++;
/*
* Copy the rest.
*/
srcb = (const uint8_t *) srcw;
dstb = (uint8_t *) dstw;
i = n;
while (i-- != 0)
*dstb++ = *srcb++;
return dst;
}
/** Move memory block with possible overlapping. */
DO_NOT_DISCARD
ATTRIBUTE_OPTIMIZE_NO_TLDP
void *memmove(void *dst, const void *src, size_t n)
{
const uint8_t *sp;
uint8_t *dp;
/* Nothing to do? */
if (src == dst)
return dst;
/* Non-overlapping? */
if (dst >= src + n || src >= dst + n) {
return memcpy(dst, src, n);
}
/* Which direction? */
if (src > dst) {
/* Forwards. */
sp = src;
dp = dst;
while (n-- != 0)
*dp++ = *sp++;
} else {
/* Backwards. */
sp = src + (n - 1);
dp = dst + (n - 1);
while (n-- != 0)
*dp-- = *sp--;
}
return dst;
}
/** Compare two memory areas.
*
* @param s1 Pointer to the first area to compare.
* @param s2 Pointer to the second area to compare.
* @param len Size of the areas in bytes.
*
* @return Zero if areas have the same contents. If they differ,
* the sign of the result is the same as the sign of the
* difference of the first pair of different bytes.
*
*/
DO_NOT_DISCARD
ATTRIBUTE_OPTIMIZE_NO_TLDP
int memcmp(const void *s1, const void *s2, size_t len)
{
uint8_t *u1 = (uint8_t *) s1;
uint8_t *u2 = (uint8_t *) s2;
size_t i;
for (i = 0; i < len; i++) {
if (*u1 != *u2)
return (int)(*u1) - (int)(*u2);
++u1;
++u2;
}
return 0;
}
/** Search memory area.
*
* @param s Memory area
* @param c Character (byte) to search for
* @param n Size of memory area in bytes
*
* @return Pointer to the first occurrence of @a c in the first @a n
* bytes of @a s or @c NULL if not found.
*/
DO_NOT_DISCARD
ATTRIBUTE_OPTIMIZE_NO_TLDP
void *memchr(const void *s, int c, size_t n)
{
uint8_t *u = (uint8_t *) s;
unsigned char uc = (unsigned char) c;
size_t i;
for (i = 0; i < n; i++) {
if (u[i] == uc)
return (void *) &u[i];
}
return NULL;
}
/** @}
*/