memset.c revision 35923
11573Srgrimes/*- 21573Srgrimes * Copyright (c) 1990, 1993 31573Srgrimes * The Regents of the University of California. All rights reserved. 41573Srgrimes * 51573Srgrimes * This code is derived from software contributed to Berkeley by 61573Srgrimes * Mike Hibler and Chris Torek. 71573Srgrimes * 81573Srgrimes * Redistribution and use in source and binary forms, with or without 91573Srgrimes * modification, are permitted provided that the following conditions 101573Srgrimes * are met: 111573Srgrimes * 1. Redistributions of source code must retain the above copyright 121573Srgrimes * notice, this list of conditions and the following disclaimer. 131573Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 141573Srgrimes * notice, this list of conditions and the following disclaimer in the 151573Srgrimes * documentation and/or other materials provided with the distribution. 161573Srgrimes * 3. All advertising materials mentioning features or use of this software 171573Srgrimes * must display the following acknowledgement: 181573Srgrimes * This product includes software developed by the University of 191573Srgrimes * California, Berkeley and its contributors. 201573Srgrimes * 4. Neither the name of the University nor the names of its contributors 211573Srgrimes * may be used to endorse or promote products derived from this software 221573Srgrimes * without specific prior written permission. 231573Srgrimes * 241573Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 251573Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 261573Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 271573Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 281573Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 291573Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 301573Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 311573Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 321573Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 331573Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 341573Srgrimes * SUCH DAMAGE. 351573Srgrimes */ 361573Srgrimes 371573Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 381573Srgrimesstatic char sccsid[] = "@(#)memset.c 8.1 (Berkeley) 6/4/93"; 391573Srgrimes#endif /* LIBC_SCCS and not lint */ 401573Srgrimes 411573Srgrimes#include <sys/types.h> 421573Srgrimes 431573Srgrimes#include <limits.h> 441573Srgrimes#include <string.h> 451573Srgrimes 461573Srgrimes#define wsize sizeof(u_int) 471573Srgrimes#define wmask (wsize - 1) 481573Srgrimes 491573Srgrimes#ifdef BZERO 501573Srgrimes#define RETURN return 511573Srgrimes#define VAL 0 521573Srgrimes#define WIDEVAL 0 531573Srgrimes 541573Srgrimesvoid 551573Srgrimesbzero(dst0, length) 561573Srgrimes void *dst0; 571573Srgrimes register size_t length; 581573Srgrimes#else 591573Srgrimes#define RETURN return (dst0) 601573Srgrimes#define VAL c0 611573Srgrimes#define WIDEVAL c 621573Srgrimes 631573Srgrimesvoid * 641573Srgrimesmemset(dst0, c0, length) 651573Srgrimes void *dst0; 661573Srgrimes register int c0; 671573Srgrimes register size_t length; 681573Srgrimes#endif 691573Srgrimes{ 701573Srgrimes register size_t t; 711573Srgrimes register u_int c; 721573Srgrimes register u_char *dst; 731573Srgrimes 741573Srgrimes dst = dst0; 751573Srgrimes /* 761573Srgrimes * If not enough words, just fill bytes. A length >= 2 words 771573Srgrimes * guarantees that at least one of them is `complete' after 781573Srgrimes * any necessary alignment. For instance: 791573Srgrimes * 801573Srgrimes * |-----------|-----------|-----------| 811573Srgrimes * |00|01|02|03|04|05|06|07|08|09|0A|00| 821573Srgrimes * ^---------------------^ 831573Srgrimes * dst dst+length-1 841573Srgrimes * 851573Srgrimes * but we use a minimum of 3 here since the overhead of the code 861573Srgrimes * to do word writes is substantial. 878870Srgrimes */ 881573Srgrimes if (length < 3 * wsize) { 891573Srgrimes while (length != 0) { 901573Srgrimes *dst++ = VAL; 911573Srgrimes --length; 921573Srgrimes } 931573Srgrimes RETURN; 941573Srgrimes } 951573Srgrimes 961573Srgrimes#ifndef BZERO 971573Srgrimes if ((c = (u_char)c0) != 0) { /* Fill the word. */ 981573Srgrimes c = (c << 8) | c; /* u_int is 16 bits. */ 991573Srgrimes#if UINT_MAX > 0xffff 1001573Srgrimes c = (c << 16) | c; /* u_int is 32 bits. */ 1011573Srgrimes#endif 1021573Srgrimes#if UINT_MAX > 0xffffffff 1031573Srgrimes c = (c << 32) | c; /* u_int is 64 bits. */ 1041573Srgrimes#endif 1051573Srgrimes } 1061573Srgrimes#endif 1071573Srgrimes /* Align destination by filling in bytes. */ 10835923Sjb if ((t = (long)dst & wmask) != 0) { 1091573Srgrimes t = wsize - t; 1101573Srgrimes length -= t; 1111573Srgrimes do { 1121573Srgrimes *dst++ = VAL; 1131573Srgrimes } while (--t != 0); 1141573Srgrimes } 1151573Srgrimes 1161573Srgrimes /* Fill words. Length was >= 2*words so we know t >= 1 here. */ 1171573Srgrimes t = length / wsize; 1181573Srgrimes do { 1191573Srgrimes *(u_int *)dst = WIDEVAL; 1201573Srgrimes dst += wsize; 1211573Srgrimes } while (--t != 0); 1221573Srgrimes 1231573Srgrimes /* Mop up trailing bytes, if any. */ 1241573Srgrimes t = length & wmask; 1251573Srgrimes if (t != 0) 1261573Srgrimes do { 1271573Srgrimes *dst++ = VAL; 1281573Srgrimes } while (--t != 0); 1291573Srgrimes RETURN; 1301573Srgrimes} 131