memset.c

来自「T-kernel 的extension源代码」· C语言 代码 · 共 67 行

/*
 *----------------------------------------------------------------------
 *    T-Kernel / Standard Extension
 *
 *    Copyright (C) 2006 by Ken Sakamura. All rights reserved.
 *    T-Kernel / Standard Extension is distributed 
 *      under the T-License for T-Kernel / Standard Extension.
 *----------------------------------------------------------------------
 *
 *    Version:   1.00.00
 *    Released by T-Engine Forum(http://www.t-engine.org) at 2006/8/11.
 *
 *----------------------------------------------------------------------
 */

/*
 *	@(#)memset.c 
 *
 */

#include <basic.h>
#include <string.h>

#define BOUND_4B_MSK	0x00000003		/* mask for boundary */

void	*memset(void *mem, int ch, size_t len)
{
	void	*m = mem;
	size_t	l;
	UW	c;

	c = (UB)ch;
	c |= (c << 8U);
	c |= (c << 16U);

	l = (unsigned)m & BOUND_4B_MSK;
	if ( l > 0 ) {
		l = 4U - l;
		if ( l > len ) {
			l = len;
		}
		len -= l;

		while ( l-- > 0 ) {
			*((UB*)m) = (UB)c;
			m = (VP)((UB*)m + 1);
		}
	}

	l = len >> 2U;
	if ( l > 0 ) {
		len &= BOUND_4B_MSK;

		while ( l-- > 0 ) {
			*((UW*)m) = c;
			m = (VP)((UW*)m + 1);
		}
	}

	while ( len-- > 0 ) {
		*((UB*)m) = (UB)c;
		m = (VP)((UB*)m + 1);
	}

	return mem;
}