Vc  1.0.0-dev
SIMD Vector Classes for C++
bitscanintrinsics.h
1 /* This file is part of the Vc library. {{{
2 Copyright © 2011-2015 Matthias Kretz <kretz@kde.org>
3 All rights reserved.
4 
5 Redistribution and use in source and binary forms, with or without
6 modification, are permitted provided that the following conditions are met:
7  * Redistributions of source code must retain the above copyright
8  notice, this list of conditions and the following disclaimer.
9  * Redistributions in binary form must reproduce the above copyright
10  notice, this list of conditions and the following disclaimer in the
11  documentation and/or other materials provided with the distribution.
12  * Neither the names of contributing organizations nor the
13  names of its contributors may be used to endorse or promote products
14  derived from this software without specific prior written permission.
15 
16 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
17 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
20 DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
23 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 
27 }}}*/
28 
29 #ifndef VC_COMMON_BITSCANINTRINSICS_H_
30 #define VC_COMMON_BITSCANINTRINSICS_H_
31 
32 #if defined(Vc_GCC) || defined(Vc_CLANG)
33 # if Vc_GCC >= 0x40500
34  // GCC 4.5.0 introduced _bit_scan_forward / _bit_scan_reverse
35 # include <x86intrin.h>
36 # else
37  // GCC <= 4.4 and clang have x86intrin.h, but not the required functions
38 # define _bit_scan_forward(x) __builtin_ctz(x)
39 #include "macros.h"
40 static Vc_ALWAYS_INLINE Vc_CONST int _Vc_bit_scan_reverse_asm(unsigned int x) {
41  int r;
42  __asm__("bsr %1,%0" : "=r"(r) : "X"(x));
43  return r;
44 }
45 # define _bit_scan_reverse(x) _Vc_bit_scan_reverse_asm(x)
46 # endif
47 #elif defined(Vc_ICC)
48 // for all I know ICC supports the _bit_scan_* intrinsics
49 #elif defined(Vc_OPEN64)
50 // TODO
51 #elif defined(Vc_MSVC)
52 #include "windows_fix_intrin.h"
53 #pragma intrinsic(_BitScanForward)
54 #pragma intrinsic(_BitScanReverse)
55 static inline __forceinline unsigned long _bit_scan_forward(unsigned long x) {
56  unsigned long index;
57  _BitScanForward(&index, x);
58  return index;
59 }
60 static inline __forceinline unsigned long _bit_scan_reverse(unsigned long x) {
61  unsigned long index;
62  _BitScanReverse(&index, x);
63  return index;
64 }
65 #else
66 // just assume the compiler can do it
67 #endif
68 
69 
70 #endif // VC_COMMON_BITSCANINTRINSICS_H_