1 dnl PowerPC-64 mpn_sublsh1_n -- rp[] = up[] - (vp[] << 1)
3 dnl Copyright 2003, 2005 Free Software Foundation, Inc.
5 dnl This file is part of the GNU MP Library.
7 dnl The GNU MP Library is free software; you can redistribute it and/or modify
8 dnl it under the terms of the GNU Lesser General Public License as published
9 dnl by the Free Software Foundation; either version 3 of the License, or (at
10 dnl your option) any later version.
12 dnl The GNU MP Library is distributed in the hope that it will be useful, but
13 dnl WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 dnl or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
15 dnl License for more details.
17 dnl You should have received a copy of the GNU Lesser General Public License
18 dnl along with the GNU MP Library. If not, see http://www.gnu.org/licenses/.
20 include(`../config.m4')
23 C POWER3/PPC630: 2 (1.5 c/l should be possible)
24 C POWER4/PPC970: 4 (2.0 c/l should be possible)
43 PROLOGUE(mpn_sublsh1_n)
44 mtctr r6 C put n in ctr
46 ld v0, 0(vp) C load v limb
47 ld u0, 0(up) C load u limb
48 addic up, up, -8 C update up; set cy
49 addi rp, rp, -8 C update rp
51 bdz L(end) C If done, skip loop
53 L(oop): ld v1, 8(vp) C load v limb
54 subfe s1, s1, u0 C add limbs with cy, set cy
55 std s1, 8(rp) C store result limb
56 srdi s0, v0, 63 C shift down previous v limb
57 ldu u0, 16(up) C load u limb and update up
58 rldimi s0, v1, 1, 0 C left shift v limb and merge with prev v limb
60 bdz L(exit) C decrement ctr and exit if done
62 ldu v0, 16(vp) C load v limb and update vp
63 subfe s0, s0, u0 C add limbs with cy, set cy
64 stdu s0, 16(rp) C store result limb and update rp
65 srdi s1, v1, 63 C shift down previous v limb
66 ld u0, 8(up) C load u limb
67 rldimi s1, v0, 1, 0 C left shift v limb and merge with prev v limb
69 bdnz L(oop) C decrement ctr and loop back
71 L(end): subfe r7, s1, u0
72 std r7, 8(rp) C store last result limb
77 L(exit): subfe r7, s0, u0
78 std r7, 16(rp) C store last result limb