usr/src/lib/libc/sparc/gen/lsub.s

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1988 AT&T */
  28 /*        All Rights Reserved   */
  29
  30         .file   "lsub.s"
  31
  32 /*
  33  * Double long subtraction routine.  Ported from pdp 11/70 version
  34  * with considerable effort.  All supplied comments were ported.
  35  * Ported from m32 version to sparc. No comments about difficulty.
  36  *
  37  *      dl_t
  38  *      lsub (lop, rop)
  39  *              dl_t    lop;
  40  *              dl_t    rop;
  41  */
  42
  43 #include "SYS.h"
  44
  45         ENTRY(lsub)
  46
  47         ld      [%o7+8],%o4             ! Instruction at ret-addr should be a
  48         cmp     %o4,8                   ! 'unimp 8' indicating a valid call.
  49         be      1f                      ! if OK, go forward.
  50         nop                             ! delay instruction.
  51         jmp     %o7+8                   ! return
  52         nop                             ! delay instruction.
  53
  54 1:
  55         ld      [%o0+0],%o2             ! fetch lop.dl_hop
  56         ld      [%o0+4],%o3             ! fetch lop.dl_lop
  57         ld      [%o1+0],%o4             ! fetch rop.dl_hop
  58         ld      [%o1+4],%o5             ! fetch rop.dl_lop
  59         subcc   %o3,%o5,%o3             ! lop.dl_lop - rop.dl_lop (set carry)
  60         subxcc  %o2,%o4,%o2             ! lop.dl_hop - rop.dl_hop - <carry>
  61         ld      [%sp+(16*4)],%o0        ! address to store result into
  62         st      %o2,[%o0]               ! store result.dl_hop
  63         jmp     %o7+12                  ! return
  64         st      %o3,[%o0+4]             ! store result.dl_lop
  65
  66         SET_SIZE(lsub)