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