minix/common/lib/libc/string/memset2.c

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/*-
* Copyright (c) 2009 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Matt Thomas <matt@3am-software.com>.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 FOUNDATION OR CONTRIBUTORS
* 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.
*/
#include <sys/types.h>
#if !defined(_KERNEL) && !defined(_STANDALONE)
#include <assert.h>
#include <limits.h>
#include <string.h>
#include <inttypes.h>
#else
#include <lib/libkern/libkern.h>
#include <machine/limits.h>
#endif
#include <sys/endian.h>
#include <machine/types.h>
#ifdef TEST
#include <assert.h>
#define _DIAGASSERT(a) assert(a)
#endif
#ifdef _FORTIFY_SOURCE
#undef bzero
#undef memset
#endif
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: memset2.c,v 1.2 2009/12/14 00:39:01 matt Exp $");
#endif /* LIBC_SCCS and not lint */
/*
* Assume uregister_t is the widest non-synthetic unsigned type.
*/
typedef uregister_t memword_t;
#ifdef BZERO
static inline
#define memset memset0
#endif
#ifdef TEST
static
#define memset test_memset
#endif
#ifdef CTASSERT
CTASSERT((~(memword_t)0U >> 1) != ~(memword_t)0U);
#endif
void *
memset(void *addr, int c, size_t len)
{
memword_t *dstp = addr;
memword_t *edstp;
memword_t fill;
#ifndef __OPTIMIZE_SIZE__
memword_t keep_mask = 0;
#endif
size_t fill_count;
_DIAGASSERT(addr != 0);
if (__predict_false(len == 0))
return addr;
/*
* Pad out the fill byte (v) across a memword_t.
* The conditional at the end prevents GCC from complaing about
* shift count >= width of type
*/
fill = c;
fill |= fill << 8;
fill |= fill << 16;
fill |= fill << (sizeof(c) < sizeof(fill) ? 32 : 0);
/*
* Get the number of unaligned bytes to fill in the first word.
*/
fill_count = -(uintptr_t)addr & (sizeof(memword_t) - 1);
if (__predict_false(fill_count != 0)) {
#ifndef __OPTIMIZE_SIZE__
/*
* We want to clear <fill_count> trailing bytes in the word.
* On big/little endian, these are the least/most significant,
* bits respectively. So as we shift, the keep_mask will only
* have bits set for the bytes we won't be filling.
*/
#if BYTE_ORDER == BIG_ENDIAN
keep_mask = ~(memword_t)0U << (fill_count * 8);
#endif
#if BYTE_ORDER == LITTLE_ENDIAN
keep_mask = ~(memword_t)0U >> (fill_count * 8);
#endif
/*
* Make sure dstp is aligned to a memword_t boundary.
*/
dstp = (memword_t *)((uintptr_t)addr & -sizeof(memword_t));
if (len >= fill_count) {
/*
* If we can fill the rest of this word, then we mask
* off the bytes we are filling and then fill in those
* bytes with the new fill value.
*/
*dstp = (*dstp & keep_mask) | (fill & ~keep_mask);
len -= fill_count;
if (__predict_false(len == 0))
return addr;
/*
* Since we were able to fill the rest of this word,
* we will advance to the next word and thus have no
* bytes to preserve.
*
* If we don't have enough to fill the rest of this
* word, we will fall through the following loop
* (since there are no full words to fill). Then we
* use the keep_mask above to preserve the leading
* bytes of word.
*/
dstp++;
keep_mask = 0;
} else {
len += (uintptr_t)addr & (sizeof(memword_t) - 1);
}
#else /* __OPTIMIZE_SIZE__ */
uint8_t *dp, *ep;
if (len < fill_count)
fill_count = len;
for (dp = (uint8_t *)dstp, ep = dp + fill_count;
dp != ep; dp++)
*dp = fill;
if ((len -= fill_count) == 0)
return addr;
dstp = (memword_t *)ep;
#endif /* __OPTIMIZE_SIZE__ */
}
/*
* Simply fill memory one word at time (for as many full words we have
* to write).
*/
for (edstp = dstp + len / sizeof(memword_t); dstp != edstp; dstp++)
*dstp = fill;
/*
* We didn't subtract out the full words we just filled since we know
* by the time we get here we will have less than a words worth to
* write. So we can concern ourselves with only the subword len bits.
*/
len &= sizeof(memword_t)-1;
if (len > 0) {
#ifndef __OPTIMIZE_SIZE__
/*
* We want to clear <len> leading bytes in the word.
* On big/little endian, these are the most/least significant
* bits, respectively, But as we want the mask of the bytes to
* keep, we have to complement the mask. So after we shift,
* the keep_mask will only have bits set for the bytes we won't
* be filling.
*
* But the keep_mask could already have bytes to preserve
* if the amount to fill was less than the amount of traiing
* space in the first word.
*/
#if BYTE_ORDER == BIG_ENDIAN
keep_mask |= ~(memword_t)0U >> (len * 8);
#endif
#if BYTE_ORDER == LITTLE_ENDIAN
keep_mask |= ~(memword_t)0U << (len * 8);
#endif
/*
* Now we mask off the bytes we are filling and then fill in
* those bytes with the new fill value.
*/
*dstp = (*dstp & keep_mask) | (fill & ~keep_mask);
#else /* __OPTIMIZE_SIZE__ */
uint8_t *dp, *ep;
for (dp = (uint8_t *)dstp, ep = dp + len;
dp != ep; dp++)
*dp = fill;
#endif /* __OPTIMIZE_SIZE__ */
}
/*
* Return the initial addr
*/
return addr;
}
#ifdef BZERO
/*
* For bzero, simply inline memset and let the compiler optimize things away.
*/
void
bzero(void *addr, size_t len)
{
memset(addr, 0, len);
}
#endif
#ifdef TEST
#include <stdbool.h>
#include <stdio.h>
#undef memset
static union {
uint8_t bytes[sizeof(memword_t) * 4];
memword_t words[4];
} testmem;
int
main(int argc, char **argv)
{
size_t start;
size_t len;
bool failed = false;
for (start = 1; start < sizeof(testmem) - 1; start++) {
for (len = 1; start + len < sizeof(testmem) - 1; len++) {
bool ok = true;
size_t i;
uint8_t check_value;
memset(testmem.bytes, 0xff, sizeof(testmem));
test_memset(testmem.bytes + start, 0x00, len);
for (i = 0; i < sizeof(testmem); i++) {
if (i == 0 || i == start + len)
check_value = 0xff;
else if (i == start)
check_value = 0x00;
if (testmem.bytes[i] != check_value) {
if (ok)
printf("pass @ %zu .. %zu failed",
start, start + len - 1);
ok = false;
printf(" [%zu]=0x%02x(!0x%02x)",
i, testmem.bytes[i], check_value);
}
}
if (!ok) {
printf("\n");
failed = 1;
}
}
}
return failed ? 1 : 0;
}
#endif /* TEST */