1/* $NetBSD: memmove.S,v 1.3 2011/01/25 04:45:28 matt Exp $ */ 2/*- 3 * Copyright (c) 1990, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31#include <machine/asm.h> 32 33/* .asciz "@(#)memmove.s 8.1 (Berkeley) 6/4/93" */ 34RCSID("$NetBSD: memmove.S,v 1.3 2011/01/25 04:45:28 matt Exp $") 35 36/* 37 * void *memmove(dst, src, size) 38 * returns dst 39 * 40 * This optimises the usual case (count < 65536) at the expense 41 * of some extra memory references and branches when count >= 65536. 42 */ 43 44ENTRY(memmove, 0) 45 movzwl $65535,%r0 /* %r0 = 64K (needed below) */ 46 movq 8(%ap),%r1 /* %r1 = src, %r2 = length */ 47 movl 4(%ap),%r3 /* %r3 = dst */ 48 cmpl %r1,%r3 49 bgtru 1f /* normal forward case */ 50 beql 2f /* equal, nothing to do */ 51 addl2 %r2,%r1 /* overlaps iff src<dst but src+len>dst */ 52 cmpl %r1,%r3 53 bgtru 4f /* overlapping, must move backwards */ 54 subl2 %r2,%r1 55 561: /* move forward */ 57 cmpl %r2,%r0 58 bgtru 3f /* stupid movc3 limitation */ 59 movc3 %r2,(%r1),(%r3) /* move it all */ 602: 61 movl 4(%ap),%r0 /* return original dst */ 62 ret 633: 64 subl2 %r0,12(%ap) /* adjust length by 64K */ 65 movc3 %r0,(%r1),(%r3) /* move 64K */ 66 movl 12(%ap),%r2 67 decw %r0 /* from 0 to 65535 */ 68 brb 1b /* retry */ 69 704: /* move backward */ 71 addl2 %r2,%r3 725: 73 cmpl %r2,%r0 74 bgtru 6f /* stupid movc3 limitation */ 75 subl2 %r2,%r1 76 subl2 %r2,%r3 77 movc3 %r2,(%r1),(%r3) /* move it all */ 78 movl 4(%ap),%r0 /* return original dst */ 79 ret 806: 81 subl2 %r0,12(%ap) /* adjust length by 64K */ 82 subl2 %r0,%r1 83 subl2 %r0,%r3 84 movc3 %r0,(%r1),(%r3) /* move 64K */ 85 movl 12(%ap),%r2 86 decw %r0 87 subl2 %r0,%r1 88 subl2 %r0,%r3 89 brb 5b 90END(memmove) 91