memset.S (2780B)
1 /* 2 * Copyright (c) 1993 Winning Strategies, Inc. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by Winning Strategies, Inc. 16 * 4. The name of the author may not be used to endorse or promote products 17 * derived from this software without specific prior written permission 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 #include <asm.h> 32 33 /* 34 * memset(void *b, int c, size_t len) 35 * write len bytes of value c (converted to an unsigned char) to 36 * the string b. 37 * 38 * Written by: 39 * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. 40 */ 41 42 ENTRY(memset) 43 pushl %edi 44 pushl %ebx 45 movl 12(%esp),%edi 46 movzbl 16(%esp),%eax /* unsigned char, zero extend */ 47 movl 20(%esp),%ecx 48 pushl %edi /* push address of buffer */ 49 50 cld /* set fill direction forward */ 51 52 /* 53 * if the string is too short, it's really not worth the overhead 54 * of aligning to word boundries, etc. So we jump to a plain 55 * unaligned set. 56 */ 57 cmpl $0x0f,%ecx 58 jle L1 59 60 movb %al,%ah /* copy char to all bytes in word */ 61 movl %eax,%edx 62 sall $16,%eax 63 orl %edx,%eax 64 65 movl %edi,%edx /* compute misalignment */ 66 negl %edx 67 andl $3,%edx 68 movl %ecx,%ebx 69 subl %edx,%ebx 70 71 movl %edx,%ecx /* set until word aligned */ 72 rep 73 stosb 74 75 movl %ebx,%ecx 76 shrl $2,%ecx /* set by words */ 77 rep 78 stosl 79 80 movl %ebx,%ecx /* set remainder by bytes */ 81 andl $3,%ecx 82 L1: rep 83 stosb 84 85 popl %eax /* pop address of buffer */ 86 popl %ebx 87 popl %edi 88 ret