/* $NetBSD: memmove.S,v 1.3 2011/01/25 04:45:28 matt Exp $ */ /*- * Copyright (c) 1990, 1993 * The Regents of the University of California. 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. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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> /* .asciz "@(#)memmove.s 8.1 (Berkeley) 6/4/93" */ RCSID("$NetBSD: memmove.S,v 1.3 2011/01/25 04:45:28 matt Exp $") /* * void *memmove(dst, src, size) * returns dst * * This optimises the usual case (count < 65536) at the expense * of some extra memory references and branches when count >= 65536. */ ENTRY(memmove, 0) movzwl $65535,%r0 /* %r0 = 64K (needed below) */ movq 8(%ap),%r1 /* %r1 = src, %r2 = length */ movl 4(%ap),%r3 /* %r3 = dst */ cmpl %r1,%r3 bgtru 1f /* normal forward case */ beql 2f /* equal, nothing to do */ addl2 %r2,%r1 /* overlaps iff src<dst but src+len>dst */ cmpl %r1,%r3 bgtru 4f /* overlapping, must move backwards */ subl2 %r2,%r1 1: /* move forward */ cmpl %r2,%r0 bgtru 3f /* stupid movc3 limitation */ movc3 %r2,(%r1),(%r3) /* move it all */ 2: movl 4(%ap),%r0 /* return original dst */ ret 3: subl2 %r0,12(%ap) /* adjust length by 64K */ movc3 %r0,(%r1),(%r3) /* move 64K */ movl 12(%ap),%r2 decw %r0 /* from 0 to 65535 */ brb 1b /* retry */ 4: /* move backward */ addl2 %r2,%r3 5: cmpl %r2,%r0 bgtru 6f /* stupid movc3 limitation */ subl2 %r2,%r1 subl2 %r2,%r3 movc3 %r2,(%r1),(%r3) /* move it all */ movl 4(%ap),%r0 /* return original dst */ ret 6: subl2 %r0,12(%ap) /* adjust length by 64K */ subl2 %r0,%r1 subl2 %r0,%r3 movc3 %r0,(%r1),(%r3) /* move 64K */ movl 12(%ap),%r2 decw %r0 subl2 %r0,%r1 subl2 %r0,%r3 brb 5b END(memmove) |