1dnl  mpn_half
2
3dnl  Copyright 2011 The Code Cavern
4
5dnl  This file is part of the MPIR Library.
6
7dnl  The MPIR Library is free software; you can redistribute it and/or modify
8dnl  it under the terms of the GNU Lesser General Public License as published
9dnl  by the Free Software Foundation; either version 2.1 of the License, or (at
10dnl  your option) any later version.
11
12dnl  The MPIR Library is distributed in the hope that it will be useful, but
13dnl  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14dnl  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
15dnl  License for more details.
16
17dnl  You should have received a copy of the GNU Lesser General Public License
18dnl  along with the MPIR Library; see the file COPYING.LIB.  If not, write
19dnl  to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
20dnl  Boston, MA 02110-1301, USA.
21
22include(`../config.m4')
23
24ASM_START()
25PROLOGUE(mpn_half)
26mov %rsi,%rax
27lea -8(%rdi,%rsi,8),%rdi
28shr $2,%rsi
29and $3,%eax
30jz t1
31shrq $1,(%rdi)
32lea -8(%rdi),%rdi
33dec %rax
34jz t1
35rcrq $1,(%rdi)
36lea -8(%rdi),%rdi
37dec %rax
38jz t1
39rcrq $1,(%rdi)
40lea -8(%rdi),%rdi
41dec %rax
42t1:
43sbb %rdx,%rdx
44cmp $0,%rsi
45jz skiplp
46add %rdx,%rdx
47.align 16
48lp:
49  rcrq $1,(%rdi)
50  nop
51  rcrq $1,-8(%rdi)
52  rcrq $1,-16(%rdi)
53  rcrq $1,-24(%rdi)
54  nop
55  dec %rsi
56  lea -32(%rdi),%rdi
57  jnz lp
58sbb %rdx,%rdx
59skiplp:
60sub %rdx,%rax
61shl $63,%rax
62ret
63EPILOGUE()
64