lib/libutils/isoc/newlib/memset.c

// SPDX-License-Identifier: BSD-3-Clause
/*
 * Copyright (c) 1994-2009  Red Hat, Inc.
 * All rights reserved.
 *
 * 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 copyright holder 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 COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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
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 */

/*
FUNCTION
	<<memset>>---set an area of memory

INDEX
	memset

ANSI_SYNOPSIS
	#include <string.h>
	void *memset(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 <[dst]>.

PORTABILITY
<<memset>> is ANSI C.

    <<memset>> requires no supporting OS subroutines.

QUICKREF
	memset ansi pure
*/

#include "_ansi.h"
#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)
{
	char *s = (char *)m;

#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.  */

	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;

		/* 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;
	}
#endif /* not PREFER_SIZE_OVER_SPEED */

	while (n--)
		*s++ = (char)c;

	return m;
}