swab.S revision 1.7
1 1.1 cgd /* 2 1.6 jtc * Copyright (c) 1993,94 Winning Strategies, Inc. 3 1.1 cgd * All rights reserved. 4 1.1 cgd * 5 1.1 cgd * Redistribution and use in source and binary forms, with or without 6 1.1 cgd * modification, are permitted provided that the following conditions 7 1.1 cgd * are met: 8 1.1 cgd * 1. Redistributions of source code must retain the above copyright 9 1.1 cgd * notice, this list of conditions and the following disclaimer. 10 1.1 cgd * 2. Redistributions in binary form must reproduce the above copyright 11 1.1 cgd * notice, this list of conditions and the following disclaimer in the 12 1.1 cgd * documentation and/or other materials provided with the distribution. 13 1.1 cgd * 3. All advertising materials mentioning features or use of this software 14 1.1 cgd * must display the following acknowledgement: 15 1.1 cgd * This product includes software developed by Winning Strategies, Inc. 16 1.1 cgd * 4. The name of the author may not be used to endorse or promote products 17 1.5 jtc * derived from this software without specific prior written permission 18 1.1 cgd * 19 1.1 cgd * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 1.1 cgd * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 1.1 cgd * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 1.1 cgd * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 1.1 cgd * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 1.1 cgd * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 1.1 cgd * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 1.1 cgd * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 1.1 cgd * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 1.1 cgd * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 1.1 cgd * 30 1.7 jtc * $Id: swab.S,v 1.7 1994/03/12 01:40:09 jtc Exp $ 31 1.1 cgd */ 32 1.1 cgd 33 1.7 jtc #include <machine/asm.h> 34 1.7 jtc 35 1.2 jtc #if defined(LIBC_SCCS) 36 1.7 jtc RCSID("$Id: swab.S,v 1.7 1994/03/12 01:40:09 jtc Exp $") 37 1.1 cgd #endif 38 1.1 cgd 39 1.1 cgd /* 40 1.1 cgd * void 41 1.1 cgd * swab (const void *src, void *dst, size_t len) 42 1.1 cgd * copy len bytes from src to dst, swapping adjacent bytes 43 1.1 cgd * 44 1.1 cgd * On the i486, this code is negligibly faster than the code generated 45 1.3 jtc * by gcc at about half the size. If my i386 databook is correct, it 46 1.1 cgd * should be considerably faster than the gcc code on a i386. 47 1.1 cgd * 48 1.1 cgd * Written by: 49 1.1 cgd * J.T. Conklin (jtc (at) wimsey.com), Winning Strategies, Inc. 50 1.1 cgd */ 51 1.1 cgd 52 1.1 cgd ENTRY(swab) 53 1.1 cgd pushl %esi 54 1.1 cgd pushl %edi 55 1.1 cgd movl 12(%esp),%esi 56 1.1 cgd movl 16(%esp),%edi 57 1.1 cgd movl 20(%esp),%ecx 58 1.1 cgd 59 1.1 cgd cld # set direction forward 60 1.1 cgd 61 1.4 jtc shrl $1,%ecx 62 1.1 cgd testl $7,%ecx # copy first group of 1 to 7 words 63 1.4 jtc jz L2 # while swaping alternate bytes. 64 1.1 cgd .align 2,0x90 65 1.1 cgd L1: lodsw 66 1.6 jtc rorw $8,%ax 67 1.1 cgd stosw 68 1.1 cgd decl %ecx 69 1.1 cgd testl $7,%ecx 70 1.4 jtc jnz L1 71 1.3 jtc 72 1.1 cgd L2: shrl $3,%ecx # copy remainder 8 words at a time 73 1.1 cgd jz L4 # while swapping alternate bytes. 74 1.1 cgd .align 2,0x90 75 1.1 cgd L3: lodsw 76 1.6 jtc rorw $8,%ax 77 1.1 cgd stosw 78 1.1 cgd lodsw 79 1.6 jtc rorw $8,%ax 80 1.1 cgd stosw 81 1.1 cgd lodsw 82 1.6 jtc rorw $8,%ax 83 1.1 cgd stosw 84 1.1 cgd lodsw 85 1.6 jtc rorw $8,%ax 86 1.1 cgd stosw 87 1.1 cgd lodsw 88 1.6 jtc rorw $8,%ax 89 1.1 cgd stosw 90 1.1 cgd lodsw 91 1.6 jtc rorw $8,%ax 92 1.1 cgd stosw 93 1.1 cgd lodsw 94 1.6 jtc rorw $8,%ax 95 1.1 cgd stosw 96 1.1 cgd lodsw 97 1.6 jtc rorw $8,%ax 98 1.1 cgd stosw 99 1.1 cgd decl %ecx 100 1.1 cgd jnz L3 101 1.1 cgd 102 1.6 jtc L4: popl %edi 103 1.1 cgd popl %esi 104 1.1 cgd ret 105
Indexes created Mon Sep 22 10:09:38 GMT 2025