| dnl ARM v5 mpn_gcd_1. |
| |
| dnl Based on the K7 gcd_1.asm, by Kevin Ryde. Rehacked for ARM by Torbjรถrn |
| dnl Granlund. |
| |
| dnl Copyright 2000-2002, 2005, 2009, 2011, 2012 Free Software Foundation, Inc. |
| |
| dnl This file is part of the GNU MP Library. |
| dnl |
| dnl The GNU MP Library is free software; you can redistribute it and/or modify |
| dnl it under the terms of either: |
| dnl |
| dnl * the GNU Lesser General Public License as published by the Free |
| dnl Software Foundation; either version 3 of the License, or (at your |
| dnl option) any later version. |
| dnl |
| dnl or |
| dnl |
| dnl * the GNU General Public License as published by the Free Software |
| dnl Foundation; either version 2 of the License, or (at your option) any |
| dnl later version. |
| dnl |
| dnl or both in parallel, as here. |
| dnl |
| dnl The GNU MP Library is distributed in the hope that it will be useful, but |
| dnl WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| dnl or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| dnl for more details. |
| dnl |
| dnl You should have received copies of the GNU General Public License and the |
| dnl GNU Lesser General Public License along with the GNU MP Library. If not, |
| dnl see https://www.gnu.org/licenses/. |
| |
| include(`../config.m4') |
| |
| C cycles/bit (approx) |
| C StrongARM - |
| C XScale ? |
| C Cortex-A7 ? |
| C Cortex-A8 ? |
| C Cortex-A9 5.9 |
| C Cortex-A15 ? |
| C Numbers measured with: speed -CD -s8-32 -t24 mpn_gcd_1 |
| |
| C TODO |
| C * Optimise inner-loop better. |
| |
| C Threshold of when to call bmod when U is one limb. Should be about |
| C (time_in_cycles(bmod_1,1) + call_overhead) / (cycles/bit). |
| define(`BMOD_THRES_LOG2', 6) |
| |
| C INPUT PARAMETERS |
| define(`up', `r0') |
| define(`n', `r1') |
| define(`v0', `r2') |
| |
| ifdef(`BMOD_1_TO_MOD_1_THRESHOLD',, |
| `define(`BMOD_1_TO_MOD_1_THRESHOLD',0xffffffff)') |
| |
| ASM_START() |
| TEXT |
| ALIGN(16) |
| PROLOGUE(mpn_gcd_1) |
| push {r4, r7, lr} |
| ldr r3, [up] C U low limb |
| |
| orr r3, r3, v0 |
| rsb r4, r3, #0 |
| and r4, r4, r3 |
| clz r4, r4 C min(ctz(u0),ctz(v0)) |
| rsb r4, r4, #31 |
| |
| rsb r12, v0, #0 |
| and r12, r12, v0 |
| clz r12, r12 |
| rsb r12, r12, #31 |
| mov v0, v0, lsr r12 |
| |
| mov r7, v0 |
| |
| cmp n, #1 |
| bne L(nby1) |
| |
| C Both U and V are single limbs, reduce with bmod if u0 >> v0. |
| ldr r3, [up] |
| cmp v0, r3, lsr #BMOD_THRES_LOG2 |
| bhi L(red1) |
| |
| L(bmod):mov r3, #0 C carry argument |
| bl mpn_modexact_1c_odd |
| b L(red0) |
| |
| L(nby1):cmp n, #BMOD_1_TO_MOD_1_THRESHOLD |
| blo L(bmod) |
| |
| bl mpn_mod_1 |
| |
| L(red0):mov r3, r0 |
| L(red1):rsbs r12, r3, #0 |
| and r12, r12, r3 |
| clz r12, r12 |
| rsb r12, r12, #31 |
| bne L(mid) |
| b L(end) |
| |
| ALIGN(8) |
| L(top): rsb r12, r12, #31 |
| movcc r3, r1 C if x-y < 0 |
| movcc r7, r0 C use x,y-x |
| L(mid): mov r3, r3, lsr r12 C |
| mov r0, r3 C |
| sub r1, r7, r3 C |
| rsbs r3, r7, r3 C |
| and r12, r1, r3 C |
| clz r12, r12 C |
| bne L(top) C |
| |
| L(end): mov r0, r7, lsl r4 |
| pop {r4, r7, pc} |
| EPILOGUE() |
