/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

        .file   "__align_cpy_8.s"

/* __align_cpy_8(s1, s2, n)
 *
 * Copy 8-byte aligned source to 8-byte aligned target in multiples of 8 bytes.
 *
 * Input:
 *      o0      address of target
 *      o1      address of source
 *      o2      number of bytes to copy (must be a multiple of 8)
 * Output:
 *      o0      address of target
 * Caller's registers that have been changed by this function:
 *      o1-o5
 *
 * Note:
 *      This helper routine will not be used by any 32-bit compilations. To do
 *      so would break binary compatibility with previous versions of Solaris.
 *
 * Assumptions:
 *      Source and target addresses are 8-byte aligned.
 *      Bytes to be copied are non-overlapping or _exactly_ overlapping.
 *      The number of bytes to be copied is a multiple of 8.
 *      Call will _usually_ be made with a byte count of more than 4*8 and
 *      less than a few hundred bytes.  Legal values are 0 to MAX_SIZE_T.
 *
 * Optimization attempt:
 *      Reasonable speed for a generic v9.  Going for 32 bytes at a time
 *      rather than 16 bytes at a time did not result in a time saving for
 *      the number of bytes expected to be copied.  No timing runs using other
 *      levels of optimization have been tried yet.
 *
 * Even when multiples of 16 bytes were used, the savings by going for 32 bytes
 * at a time were about 2%.  Thus, __align_cpy_16 is a second entry point to
 * the same code as __align_cpy_8.
 *
 * Register usage:
 *      o1      source address (updated for each read)
 *      o2      byte count remaining
 *      o3      contents being copied
 *      o4      more contents being copied
 *      o5      target address
 */

#include <sys/asm_linkage.h>

        ENTRY(__align_cpy_8)
        ENTRY(__align_cpy_16)
        cmp     %o0, %o1                ! Identical--do nothing.
        be,pn   %xcc, .done
        subcc   %o2, 8, %o2
        bz,pn   %xcc, .wrdbl2           ! Only 8 bytes need to be copied.
        mov     %o0, %o5                ! Original target address is returned.
        bpos,a,pt %xcc, .wrdbl1         ! Have at least 16 bytes to copy.
        ldx     [%o1], %o3
.done:
        retl                            ! No bytes to copy.
        nop

        .align  32
.wrdbl1:                                ! Copy 16 bytes at a time.
        subcc   %o2, 16, %o2
        ldx     [%o1+8], %o4
        add     %o1, 16, %o1
        stx     %o3, [%o5]
        stx     %o4, [%o5+8]
        add     %o5, 16, %o5
        bg,a,pt %xcc, .wrdbl1           ! Have at least 16 more bytes.
        ldx     [%o1], %o3

        bz,a,pt %xcc, .wrdbl3           ! Have 8 bytes remaining to copy.
        ldx     [%o1], %o3

        retl
        nop

.wrdbl2:
        ldx     [%o1], %o3              ! Copy last 8 bytes.
.wrdbl3:
        stx     %o3, [%o5]
        retl
        nop

        SET_SIZE(__align_cpy_8)
        SET_SIZE(__align_cpy_16)