Annotation of sys/lib/libkern/memset.c, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: memset.c,v 1.5 2004/08/07 00:38:32 deraadt Exp $ */
! 2: /* $NetBSD: memset.c,v 1.6 1998/03/27 05:35:47 cgd Exp $ */
! 3:
! 4: /*-
! 5: * Copyright (c) 1990, 1993
! 6: * The Regents of the University of California. All rights reserved.
! 7: *
! 8: * This code is derived from software contributed to Berkeley by
! 9: * Mike Hibler and Chris Torek.
! 10: *
! 11: * Redistribution and use in source and binary forms, with or without
! 12: * modification, are permitted provided that the following conditions
! 13: * are met:
! 14: * 1. Redistributions of source code must retain the above copyright
! 15: * notice, this list of conditions and the following disclaimer.
! 16: * 2. Redistributions in binary form must reproduce the above copyright
! 17: * notice, this list of conditions and the following disclaimer in the
! 18: * documentation and/or other materials provided with the distribution.
! 19: * 3. Neither the name of the University nor the names of its contributors
! 20: * may be used to endorse or promote products derived from this software
! 21: * without specific prior written permission.
! 22: *
! 23: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 24: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 25: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 26: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 27: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 28: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 29: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 30: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 31: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 32: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 33: * SUCH DAMAGE.
! 34: */
! 35:
! 36: #include <sys/cdefs.h>
! 37: #if defined(LIBC_SCCS) && !defined(lint)
! 38: #if 0
! 39: static char sccsid[] = "@(#)memset.c 8.1 (Berkeley) 6/4/93";
! 40: #else
! 41: __RCSID("$NetBSD: memset.c,v 1.6 1998/03/27 05:35:47 cgd Exp $");
! 42: #endif
! 43: #endif /* LIBC_SCCS and not lint */
! 44:
! 45: #include <sys/types.h>
! 46:
! 47: #if !defined(_KERNEL) && !defined(_STANDALONE)
! 48: #include <string.h>
! 49: #include <limits.h>
! 50: #else
! 51: #include <sys/limits.h>
! 52: #include <sys/systm.h>
! 53: #include <lib/libkern/libkern.h>
! 54: #endif
! 55:
! 56: #define wsize sizeof(u_int)
! 57: #define wmask (wsize - 1)
! 58:
! 59: #ifdef BZERO
! 60: #define RETURN return
! 61: #define VAL 0
! 62: #define WIDEVAL 0
! 63:
! 64: void
! 65: bzero(void *dst0, size_t length)
! 66: #else
! 67: #define RETURN return (dst0)
! 68: #define VAL c0
! 69: #define WIDEVAL c
! 70:
! 71: void *
! 72: memset(void *dst0, int c0, size_t length)
! 73: #endif
! 74: {
! 75: size_t t;
! 76: #ifndef BZERO
! 77: u_int c;
! 78: #endif
! 79: u_char *dst;
! 80:
! 81: dst = dst0;
! 82: /*
! 83: * If not enough words, just fill bytes. A length >= 2 words
! 84: * guarantees that at least one of them is `complete' after
! 85: * any necessary alignment. For instance:
! 86: *
! 87: * |-----------|-----------|-----------|
! 88: * |00|01|02|03|04|05|06|07|08|09|0A|00|
! 89: * ^---------------------^
! 90: * dst dst+length-1
! 91: *
! 92: * but we use a minimum of 3 here since the overhead of the code
! 93: * to do word writes is substantial.
! 94: */
! 95: if (length < 3 * wsize) {
! 96: while (length != 0) {
! 97: *dst++ = VAL;
! 98: --length;
! 99: }
! 100: RETURN;
! 101: }
! 102:
! 103: #ifndef BZERO
! 104: if ((c = (u_char)c0) != 0) { /* Fill the word. */
! 105: c = (c << 8) | c; /* u_int is 16 bits. */
! 106: #if UINT_MAX > 0xffff
! 107: c = (c << 16) | c; /* u_int is 32 bits. */
! 108: #endif
! 109: #if UINT_MAX > 0xffffffff
! 110: c = (c << 32) | c; /* u_int is 64 bits. */
! 111: #endif
! 112: }
! 113: #endif
! 114: /* Align destination by filling in bytes. */
! 115: if ((t = (u_long)dst & wmask) != 0) {
! 116: t = wsize - t;
! 117: length -= t;
! 118: do {
! 119: *dst++ = VAL;
! 120: } while (--t != 0);
! 121: }
! 122:
! 123: /* Fill words. Length was >= 2*words so we know t >= 1 here. */
! 124: t = length / wsize;
! 125: do {
! 126: *(u_int *)dst = WIDEVAL;
! 127: dst += wsize;
! 128: } while (--t != 0);
! 129:
! 130: /* Mop up trailing bytes, if any. */
! 131: t = length & wmask;
! 132: if (t != 0)
! 133: do {
! 134: *dst++ = VAL;
! 135: } while (--t != 0);
! 136: RETURN;
! 137: }
CVSweb