source/libs/gmp/gmp-src/mpn/power/rshift.asm

   1 dnl  IBM POWER mpn_rshift -- Shift a number right.
   2
   3 dnl  Copyright 1992, 1994, 1999-2001 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
  32 dnl  INPUT PARAMETERS
  33 dnl  res_ptr    r3
  34 dnl  s_ptr      r4
  35 dnl  size       r5
  36 dnl  cnt        r6
  37
  38 include(`../config.m4')
  39
  40 ASM_START()
  41 PROLOGUE(mpn_rshift)
  42         sfi     8,6,32
  43         mtctr   5               C put limb count in CTR loop register
  44         l       0,0(4)          C read least significant limb
  45         ai      9,3,-4          C adjust res_ptr since it's offset in the stu:s
  46         sle     3,0,8           C compute carry limb, and init MQ register
  47         bdz     Lend2           C if just one limb, skip loop
  48         lu      0,4(4)          C read 2:nd least significant limb
  49         sleq    7,0,8           C compute least significant limb of result
  50         bdz     Lend            C if just two limb, skip loop
  51 Loop:   lu      0,4(4)          C load next higher limb
  52         stu     7,4(9)          C store previous result during read latency
  53         sleq    7,0,8           C compute result limb
  54         bdn     Loop            C loop back until CTR is zero
  55 Lend:   stu     7,4(9)          C store 2:nd most significant limb
  56 Lend2:  sre     7,0,6           C compute most significant limb
  57         st      7,4(9)          C store it
  58         br
  59 EPILOGUE(mpn_rshift)