rxvtlib_rmemset.c

具有IDE功能的编辑器

#include "rxvtlib.h"

/*---------------------------------------------------------------------------*
 * File:	rmemset.c
 *---------------------------------------------------------------------------*
 * $Id: rmemset.c,v 1.17 1999/05/05 09:31:49 mason Exp $
 *
 * Copyright (C) 1997,1998 Geoff Wing <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *--------------------------------------------------------------------------*/
/*--------------------------------------------------------------------------*
 * Fast memset()
 * presumptions:
 *   1) intp_t write the best
 *   2) SIZEOF_INT_P= power of 2
 *--------------------------------------------------------------------------*/

#ifndef NO_RMEMSET
/* EXTPROTO */
void            rmemset (void *p, unsigned char c, intp_t len)
{
    u_intp_t        i, val, *rp;
    unsigned char  *lp;

    if (len < 16)		/* probably not worth all the calculations */
	lp = p;
    else {
/* write out preceding characters so we align on an integer boundary */
	if ((i = ((-(u_intp_t) p) & (SIZEOF_INT_P - 1))) == 0)
	    rp = p;
	else {
	    len -= i;
	    for (lp = p; i--;)
		*lp++ = c;
	    rp = (u_intp_t *) lp;
	}

/* do the fast writing */
	val = (c << 8) + c;
#if SIZEOF_INT_P >= 4
	val |= (val << 16);
#endif
#if SIZEOF_INT_P >= 8
	val |= (val << 32);
#endif
#if SIZEOF_INT_P == 16
	val |= (val << 64);
#endif
	for (i = len / SIZEOF_INT_P; i--;)
	    *rp++ = val;
	len &= (SIZEOF_INT_P - 1);
	lp = (unsigned char *)rp;
    }
/* write trailing characters */
    for (; len--;)
	*lp++ = c;
}
#endif