1dnl  IBM POWER mpn_rshift -- Shift a number right.
2
3dnl  Copyright 1992, 1994, 1999-2001 Free Software Foundation, Inc.
4
5dnl  This file is part of the GNU MP Library.
6dnl
7dnl  The GNU MP Library is free software; you can redistribute it and/or modify
8dnl  it under the terms of either:
9dnl
10dnl    * the GNU Lesser General Public License as published by the Free
11dnl      Software Foundation; either version 3 of the License, or (at your
12dnl      option) any later version.
13dnl
14dnl  or
15dnl
16dnl    * the GNU General Public License as published by the Free Software
17dnl      Foundation; either version 2 of the License, or (at your option) any
18dnl      later version.
19dnl
20dnl  or both in parallel, as here.
21dnl
22dnl  The GNU MP Library is distributed in the hope that it will be useful, but
23dnl  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
24dnl  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
25dnl  for more details.
26dnl
27dnl  You should have received copies of the GNU General Public License and the
28dnl  GNU Lesser General Public License along with the GNU MP Library.  If not,
29dnl  see https://www.gnu.org/licenses/.
30
31
32dnl  INPUT PARAMETERS
33dnl  res_ptr        r3
34dnl  s_ptr          r4
35dnl  size r5
36dnl  cnt  r6
37
38include(`../config.m4')
39
40ASM_START()
41PROLOGUE(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
51Loop:     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
55Lend:     stu       7,4(9)              C store 2:nd most significant limb
56Lend2:    sre       7,0,6               C compute most significant limb
57          st        7,4(9)              C store it
58          br
59EPILOGUE(mpn_rshift)
60