| dnl PowerPC-32 mpn_mod_34lsub1 -- mpn remainder mod 2^24-1. |
| |
| dnl Copyright 2002, 2003, 2005 Free Software Foundation, Inc. |
| |
| dnl This file is part of the GNU MP Library. |
| |
| dnl The GNU MP Library is free software; you can redistribute it and/or modify |
| dnl it under the terms of the GNU Lesser General Public License as published |
| dnl by the Free Software Foundation; either version 3 of the License, or (at |
| dnl your option) any later version. |
| |
| 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 Lesser General Public |
| dnl License for more details. |
| |
| dnl You should have received a copy of the GNU Lesser General Public License |
| dnl along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. |
| |
| include(`../config.m4') |
| |
| |
| C cycles/limb |
| C 603e: ? |
| C 604e: 3 |
| C 75x (G3): 3 |
| C 7400,7410 (G4): 3 |
| C 744x,745x (G4+): 3 |
| C power4/ppc970: 2.5 |
| C power5: 2.5 |
| |
| C mp_limb_t mpn_mod_34lsub1 (mp_srcptr src, mp_size_t size) |
| C |
| C There seems no need to schedule the loads back, the code is still 3.0 c/l |
| C on 750/7400 no matter where they're placed. |
| C |
| C Alternatives: |
| C |
| C Fetching half words would allow add instead for accumulating, instead of |
| C adde and its serialization. An outer loop would be required though, since |
| C 2^16 halfwords can overflow. lhz+add would be 2.0 c/l, but if there's |
| C also a bdz or bdnz for each and a pointer update say every three limbs |
| C then the total would be 2.67 c/l which isn't much faster than the current |
| C simpler code. |
| |
| ASM_START() |
| PROLOGUE(mpn_mod_34lsub1) |
| |
| C r3 src |
| C r4 size |
| |
| mtctr r4 |
| addic r6, r3, 8 C &src[2], and clear CA |
| |
| lwz r3, 0(r3) C acc0 = src[0] |
| bdz L(done) |
| |
| lwz r4, -4(r6) C acc1 = src[1] |
| bdz L(two) |
| |
| lwz r5, 0(r6) C acc2 = src[2] |
| lis r7, 0 C no carry if just three limbs |
| |
| bdz L(three) |
| lis r7, 1 C 0x10000 carry pos |
| |
| L(top): |
| C r3 acc0 |
| C r4 acc1 |
| C r5 acc2 |
| C r6 src, incrementing |
| C r7 carry pos |
| |
| lwz r0, 4(r6) |
| adde r3, r3, r0 |
| bdz L(end0) |
| |
| lwz r0, 8(r6) |
| adde r4, r4, r0 |
| bdz L(end1) |
| |
| lwzu r0, 12(r6) |
| adde r5, r5, r0 |
| bdnz L(top) |
| |
| |
| srwi r7, r7, 8 |
| L(end0): |
| srwi r7, r7, 8 |
| L(end1): |
| subfe r0, r0, r0 C -1 if not CA |
| |
| andc r7, r7, r0 C final carry, 0x10000, 0x100, 1 or 0 |
| L(three): |
| rlwinm r6, r3, 0,8,31 C acc0 low |
| |
| add r7, r7, r6 |
| rlwinm r6, r3, 8,24,31 C acc0 high |
| |
| add r7, r7, r6 |
| rlwinm r6, r4, 8,8,23 C acc1 low |
| |
| add r7, r7, r6 |
| rlwinm r6, r4, 16,16,31 C acc1 high |
| |
| add r7, r7, r6 |
| rlwinm r6, r5, 16,8,15 C acc2 low |
| |
| add r7, r7, r6 |
| rlwinm r6, r5, 24,8,31 C acc2 high |
| |
| add r3, r7, r6 |
| |
| L(done): |
| blr |
| |
| L(two): |
| C r3 acc0 |
| C r4 acc1 |
| |
| rlwinm r5, r3, 8,24,31 C acc0 high |
| rlwinm r3, r3, 0,8,31 C acc0 low |
| |
| add r3, r3, r5 C acc0 high + low |
| rlwinm r5, r4, 16,16,31 C acc1 high |
| |
| add r3, r3, r5 C add acc1 high |
| rlwinm r5, r4, 8,8,23 C acc1 low |
| |
| add r3, r3, r5 C add acc1 low |
| |
| blr |
| |
| EPILOGUE() |
