/*
 * 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.
 */

/*      Copyright (c) 1988 AT&T */
/*        All Rights Reserved   */

        .file   "lsub.s"

/*
 * Double long subtraction routine.  Ported from pdp 11/70 version
 * with considerable effort.  All supplied comments were ported.
 * Ported from m32 version to sparc. No comments about difficulty.
 *
 *      dl_t
 *      lsub (lop, rop)
 *              dl_t    lop;
 *              dl_t    rop;
 */

#include "SYS.h"

        ENTRY(lsub)

        ld      [%o7+8],%o4             ! Instruction at ret-addr should be a
        cmp     %o4,8                   ! 'unimp 8' indicating a valid call.
        be      1f                      ! if OK, go forward.
        nop                             ! delay instruction.
        jmp     %o7+8                   ! return
        nop                             ! delay instruction.

1:
        ld      [%o0+0],%o2             ! fetch lop.dl_hop
        ld      [%o0+4],%o3             ! fetch lop.dl_lop
        ld      [%o1+0],%o4             ! fetch rop.dl_hop
        ld      [%o1+4],%o5             ! fetch rop.dl_lop
        subcc   %o3,%o5,%o3             ! lop.dl_lop - rop.dl_lop (set carry)
        subxcc  %o2,%o4,%o2             ! lop.dl_hop - rop.dl_hop - <carry>
        ld      [%sp+(16*4)],%o0        ! address to store result into
        st      %o2,[%o0]               ! store result.dl_hop
        jmp     %o7+12                  ! return
        st      %o3,[%o0+4]             ! store result.dl_lop

        SET_SIZE(lsub)