sysdeps/s390/s390-64/sub_n.S

   1 /* __mpn_sub_n -- Add two limb vectors of the same length > 0 and store
   2    sum in a third limb vector.  64 bit S/390 version.
   3    Copyright (C) 2001-2022 Free Software Foundation, Inc.
   4    This file is part of the GNU MP Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public License as
   8    published by the Free Software Foundation; either version 2.1 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    see <https://www.gnu.org/licenses/>.  */
  19
  20 /* INPUT PARAMETERS
  21      %r2 = res_ptr
  22      %r3 = s1_ptr
  23      %r4 = s2_ptr
  24      %r5 = size.  */
  25
  26 #include "sysdep.h"
  27 #include "asm-syntax.h"
  28
  29 ENTRY(__mpn_sub_n)
  30         stg    %r6,48(%r15)   # save register 6
  31         cfi_offset (%r6,-112)
  32         sgr    %r1,%r1
  33         lghi   %r0,1          # cannot use ahi to add carry, use slr
  34 .L0:    lg     %r6,0(%r1,%r3) # .L0 -> no carry from last sub
  35         slg    %r6,0(%r1,%r4)
  36         stg    %r6,0(%r1,%r2)
  37         la     %r1,8(%r1)
  38         brc    4,.L3
  39 .L1:    brct   %r5,.L0
  40         slgr   %r2,%r2        # no last carry to return
  41         j      .Lexit
  42 .L2:    lg     %r6,0(%r1,%r3) # .L2 -> carry from last sub
  43         slg    %r6,0(%r1,%r4)
  44         brc    4,.L4
  45         slgr   %r6,%r0        # no carry yet, add carry from last sub
  46         stg    %r6,0(%r1,%r2)
  47         la     %r1,8(%r1)
  48         brc    11,.L1         # new carry ?
  49 .L3:    brct   %r5,.L2
  50         lgr    %r2,%r0        # return last carry
  51         j      .Lexit
  52 .L4:    slgr   %r6,%r0        # already a carry, add carry from last sub
  53         stg    %r6,0(%r1,%r2)
  54         la     %r1,8(%r1)
  55         brct   %r5,.L2
  56         lgr    %r2,%r0        # return last carry
  57 .Lexit: lg     %r6,48(%r15)   # restore register 6
  58         br     %r14
  59 END(__mpn_sub_n)