/* * Copyright (c) 1993,94 Winning Strategies, Inc. * All rights reserved. * * 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. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by Winning Strategies, Inc. * 4. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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. */ #include <machine/asm.h> __FBSDID("$FreeBSD$"); /* * void * swab (const void *src, void *dst, size_t len) * copy len bytes from src to dst, swapping adjacent bytes * * On the i486, this code is negligibly faster than the code generated * by gcc at about half the size. If my i386 databook is correct, it * should be considerably faster than the gcc code on an i386. * * Written by: * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. */ ENTRY(swab) pushl %esi pushl %edi movl 12(%esp),%esi movl 16(%esp),%edi movl 20(%esp),%ecx cld # set direction forward shrl $1,%ecx testl $7,%ecx # copy first group of 1 to 7 words jz L2 # while swaping alternate bytes. .align 2,0x90 L1: lodsw rorw $8,%ax stosw decl %ecx testl $7,%ecx jnz L1 L2: shrl $3,%ecx # copy remainder 8 words at a time jz L4 # while swapping alternate bytes. .align 2,0x90 L3: lodsw rorw $8,%ax stosw lodsw rorw $8,%ax stosw lodsw rorw $8,%ax stosw lodsw rorw $8,%ax stosw lodsw rorw $8,%ax stosw lodsw rorw $8,%ax stosw lodsw rorw $8,%ax stosw lodsw rorw $8,%ax stosw decl %ecx jnz L3 L4: popl %edi popl %esi ret END(swab) .section .note.GNU-stack,"",%progbits |