source/libs/gmp/gmp-src/mpn/thumb/sub_n.asm

   1 dnl  ARM/Thumb mpn_sub_n.
   2
   3 dnl  Copyright 1997, 2000, 2012 Free Software Foundation, Inc.
   4
   5 dnl  This file is part of the GNU MP Library.
   6 dnl
   7 dnl  The GNU MP Library is free software; you can redistribute it and/or modify
   8 dnl  it under the terms of either:
   9 dnl
  10 dnl    * the GNU Lesser General Public License as published by the Free
  11 dnl      Software Foundation; either version 3 of the License, or (at your
  12 dnl      option) any later version.
  13 dnl
  14 dnl  or
  15 dnl
  16 dnl    * the GNU General Public License as published by the Free Software
  17 dnl      Foundation; either version 2 of the License, or (at your option) any
  18 dnl      later version.
  19 dnl
  20 dnl  or both in parallel, as here.
  21 dnl
  22 dnl  The GNU MP Library is distributed in the hope that it will be useful, but
  23 dnl  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  24 dnl  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  25 dnl  for more details.
  26 dnl
  27 dnl  You should have received copies of the GNU General Public License and the
  28 dnl  GNU Lesser General Public License along with the GNU MP Library.  If not,
  29 dnl  see https://www.gnu.org/licenses/.
  30
  31 include(`../config.m4')
  32
  33 C INPUT PARAMETERS
  34 define(`rp',    r0)
  35 define(`up',    r1)
  36 define(`vp',    r2)
  37 define(`n',     r3)
  38
  39 ASM_START()
  40         .thumb
  41 PROLOGUE(mpn_sub_nc)
  42         push    {r4, r5, r6}
  43         ldr     r6, [sp, #12]           C init carry save register
  44         neg     r6, r6
  45         b       L(top)
  46 EPILOGUE()
  47 PROLOGUE(mpn_sub_n)
  48         push    {r4, r5, r6}
  49         mov     r6, n                   C init carry save register
  50
  51 L(top): ldmia   up!, {r4}               C load next limb from S1
  52         cmp     n, r6                   C tricky carry restore
  53         ldmia   vp!, {r5}               C load next limb from S2
  54         sbc     r4, r5
  55         stmia   rp!, {r4}               C store result limb to RES
  56         sbc     r6, r6                  C save negated carry
  57         sub     n, #1
  58         bne     L(top)
  59
  60         neg     r0, r6
  61         pop     {r4, r5, r6}
  62         bx      lr
  63 EPILOGUE()