/*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1990, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Mike Hibler and Chris Torek. * * 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 University 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 REGENTS 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 REGENTS 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 INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #if defined(LIBC_SCCS) && !defined(lint) static char sccsid[] = "@(#)memset.c 8.1 (Berkeley) 6/4/93"; #endif /* LIBC_SCCS and not lint */ #include #include #include #define wsize sizeof(u_long) #define wmask (wsize - 1) #ifdef BZERO #include #define RETURN return #define VAL 0 #define WIDEVAL 0 void bzero(void *dst0, size_t length) #else #include #define RETURN return (dst0) #define VAL c0 #define WIDEVAL c void * memset(void *dst0, int c0, size_t length) #endif { size_t t; #ifndef BZERO u_long c; #endif u_char *dst; dst = dst0; /* * If not enough words, just fill bytes. A length >= 2 words * guarantees that at least one of them is `complete' after * any necessary alignment. For instance: * * |-----------|-----------|-----------| * |00|01|02|03|04|05|06|07|08|09|0A|00| * ^---------------------^ * dst dst+length-1 * * but we use a minimum of 3 here since the overhead of the code * to do word writes is substantial. * * TODO: This threshold might not be sensible for 64-bit u_long. * We should benchmark and revisit this decision. */ if (length < 3 * wsize) { while (length != 0) { *dst++ = VAL; --length; } RETURN; } #ifndef BZERO if ((c = (u_char)c0) != 0) { /* Fill the word. */ c = (c << 8) | c; /* u_long is 16 bits. */ #if ULONG_MAX > 0xffff c = (c << 16) | c; /* u_long is 32 bits. */ #endif #if ULONG_MAX > 0xffffffff c = (c << 32) | c; /* u_long is 64 bits. */ #endif } #endif /* Align destination by filling in bytes. */ if ((t = (long)dst & wmask) != 0) { t = wsize - t; length -= t; do { *dst++ = VAL; } while (--t != 0); } /* Fill words. Length was >= 2*words so we know t >= 1 here. */ t = length / wsize; do { *(u_long *)(void *)dst = WIDEVAL; dst += wsize; } while (--t != 0); /* Mop up trailing bytes, if any. */ t = length & wmask; if (t != 0) do { *dst++ = VAL; } while (--t != 0); RETURN; }