sysdeps/rs6000/sub_n.s

   1 # IBM POWER __mpn_sub_n -- Subtract two limb vectors of equal, non-zero length.
   2
   3 # Copyright (C) 1992, 1994, 1995, 1996 Free Software Foundation, Inc.
   4
   5 # This file is part of the GNU MP Library.
   6
   7 # The GNU MP Library is free software; you can redistribute it and/or modify
   8 # it under the terms of the GNU Library General Public License as published by
   9 # the Free Software Foundation; either version 2 of the License, or (at your
  10 # option) any later version.
  11
  12 # The GNU MP Library is distributed in the hope that it will be useful, but
  13 # WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14 # or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
  15 # License for more details.
  16
  17 # You should have received a copy of the GNU Library General Public License
  18 # along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
  19 # the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  20 # MA 02111-1307, USA.
  21
  22
  23 # INPUT PARAMETERS
  24 # res_ptr       r3
  25 # s1_ptr        r4
  26 # s2_ptr        r5
  27 # size          r6
  28
  29         .toc
  30         .extern __mpn_sub_n[DS]
  31         .extern .__mpn_sub_n
  32 .csect [PR]
  33         .align 2
  34         .globl __mpn_sub_n
  35         .globl .__mpn_sub_n
  36         .csect __mpn_sub_n[DS]
  37 __mpn_sub_n:
  38         .long .__mpn_sub_n, TOC[tc0], 0
  39         .csect [PR]
  40 .__mpn_sub_n:
  41         andil.  10,6,1          # odd or even number of limbs?
  42         l       8,0(4)          # load least significant s1 limb
  43         l       0,0(5)          # load least significant s2 limb
  44         cal     3,-4(3)         # offset res_ptr, it's updated before it's used
  45         sri     10,6,1          # count for unrolled loop
  46         sf      7,0,8           # subtract least significant limbs, set cy
  47         mtctr   10              # copy count into CTR
  48         beq     0,Leven         # branch if even # of limbs (# of limbs >= 2)
  49
  50 # We have an odd # of limbs.  Add the first limbs separately.
  51         cmpi    1,10,0          # is count for unrolled loop zero?
  52         bne     1,L1            # branch if not
  53         st      7,4(3)
  54         sfe     3,0,0           # load !cy into ...
  55         sfi     3,3,0           # ... return value register
  56         br                      # return
  57
  58 # We added least significant limbs.  Now reload the next limbs to enter loop.
  59 L1:     lu      8,4(4)          # load s1 limb and update s1_ptr
  60         lu      0,4(5)          # load s2 limb and update s2_ptr
  61         stu     7,4(3)
  62         sfe     7,0,8           # subtract limbs, set cy
  63 Leven:  lu      9,4(4)          # load s1 limb and update s1_ptr
  64         lu      10,4(5)         # load s2 limb and update s2_ptr
  65         bdz     Lend            # If done, skip loop
  66
  67 Loop:   lu      8,4(4)          # load s1 limb and update s1_ptr
  68         lu      0,4(5)          # load s2 limb and update s2_ptr
  69         sfe     11,10,9         # subtract previous limbs with cy, set cy
  70         stu     7,4(3)          #
  71         lu      9,4(4)          # load s1 limb and update s1_ptr
  72         lu      10,4(5)         # load s2 limb and update s2_ptr
  73         sfe     7,0,8           # subtract previous limbs with cy, set cy
  74         stu     11,4(3)         #
  75         bdn     Loop            # decrement CTR and loop back
  76
  77 Lend:   sfe     11,10,9         # subtract limbs with cy, set cy
  78         st      7,4(3)          #
  79         st      11,8(3)         #
  80         sfe     3,0,0           # load !cy into ...
  81         sfi     3,3,0           # ... return value register
  82         br