sdk/lib/freestanding/memset.c

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mike Hibler and Chris Torek.
 *
 * 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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 <cdefs.h>
#include <stddef.h>
#include <string.h>

#define wsize sizeof(unsigned int)
#define wmask (wsize - 1)

void *memset(void *dst0, int c0, size_t length)
{
	size_t         t;
	unsigned int   c;
	unsigned char *dst;

	dst = dst0;
	if (length < 3 * wsize)
	{
		while (length != 0)
		{
			*dst++ = c0;
			--length;
		}
		return (dst0);
	}

	if ((c = (unsigned char)c0) != 0)
	{
		c = (c << 8) | c;
		c = (c << 16) | c; /* u_int is 32 bits. */
	}
	/* Align destination by filling in bytes. */
	if ((t = (long)dst & wmask) != 0)
	{
		t = wsize - t;
		length -= t;
		do
		{
			*dst++ = c0;
		} while (--t != 0);
	}

	/* Fill words.  Length was >= 2*words so we know t >= 1 here. */
	t = length / wsize;
	do
	{
		*(unsigned int *)(void *)dst = c;
		dst += wsize;
	} while (--t != 0);

	/* Mop up trailing bytes, if any. */
	t = length & wmask;
	if (t != 0)
		do
		{
			*dst++ = c0;
		} while (--t != 0);
	return (dst0);
}

void __cheri_libcall explicit_bzero(void *s, size_t n)
{
	memset(s, 0, n);
}