| dnl PowerPC-64 mpn_divexact_by3 -- mpn by 3 exact division |
| |
| dnl Copyright 2006 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 POWER3/PPC630: 13 |
| C POWER4/PPC970: 13 |
| C POWER5: 13 |
| |
| C INPUT PARAMETERS |
| define(`rp', `r3') |
| define(`up', `r4') |
| define(`n', `r5') |
| define(`cy', `r6') |
| |
| define(`xAAAAAAAB',`r7') |
| define(`xAAAAAAAA', `r9') |
| define(`q', `r10') |
| define(`ul', `r11') |
| define(`one', `r12') |
| |
| |
| ASM_START() |
| PROLOGUE(mpn_divexact_by3c) |
| |
| mtctr r5 |
| li r7, -0x5556 C 0xFFFFFFFFFFFFAAAA |
| ld ul, 0(up) |
| rldimi r7, r7, 16, 32 C 0xFFFFFFFFAAAAAAAA |
| rldimi r7, r7, 32, 63 C 0xAAAAAAAAAAAAAAAB = 1/3 |
| |
| addi r9, r7, -1 C 0xAAAAAAAAAAAAAAAA |
| li one, 1 |
| |
| subfc ul, cy, ul C C = (cy <= up[0]) |
| subfe cy, r1, r1 C cy = -(cy > up[0]) |
| bdz L(end) |
| |
| ALIGN(16) |
| L(top): mulld q, ul, xAAAAAAAB |
| |
| ld ul, 8(up) |
| addi up, up, 8 |
| addc r0, xAAAAAAAA, q C set C flag if q >= 0x5555...56 |
| |
| subfe cy, cy, one C cy = 1-cy-1+C |
| subfc r0, q, xAAAAAAAA C set C flag if q < 0xAAAA...AA |
| |
| subfe ul, cy, ul C ul = ul-cy-1+C |
| std q, 0(rp) |
| addi rp, rp, 8 |
| |
| subfe cy, r1, r1 |
| bdnz L(top) |
| |
| L(end): mulld q, ul, xAAAAAAAB |
| addc r0, xAAAAAAAA, q |
| |
| subfe cy, cy, one |
| subfc r0, q, xAAAAAAAA |
| |
| std q, 0(rp) |
| subfe r3, r1, r1 |
| subf r3, r3, cy |
| blr |
| EPILOGUE() |
