| Austin Schuh | bb1338c | 2024-06-15 19:31:16 -0700 | [diff] [blame] | 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) |