Vc  1.4.2
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 
4 Redistribution and use in source and binary forms, with or without
5 modification, are permitted provided that the following conditions are met:
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7  notice, this list of conditions and the following disclaimer.
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9  notice, this list of conditions and the following disclaimer in the
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15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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26 }}}*/
27 
28 #ifndef VC_COMMON_BITSCANINTRINSICS_H_
29 #define VC_COMMON_BITSCANINTRINSICS_H_
30 
31 #if defined(Vc_GCC) || defined(Vc_CLANG) || defined(Vc_APPLECLANG)
32 #include <x86intrin.h>
33 # ifndef _bit_scan_forward
34 # define _bit_scan_forward(x) __builtin_ctz(x)
35 #include "macros.h"
36 static Vc_ALWAYS_INLINE Vc_CONST int _Vc_bit_scan_reverse_asm(unsigned int x) {
37  int r;
38  __asm__("bsr %1,%0" : "=r"(r) : "X"(x));
39  return r;
40 }
41 # define _bit_scan_reverse(x) _Vc_bit_scan_reverse_asm(x)
42 # endif
43 #elif defined(_WIN32)
44 #include <intrin.h>
45 static inline __forceinline unsigned long _bit_scan_forward(unsigned long x) {
46  unsigned long index;
47  _BitScanForward(&index, x);
48  return index;
49 }
50 static inline __forceinline unsigned long _bit_scan_reverse(unsigned long x) {
51  unsigned long index;
52  _BitScanReverse(&index, x);
53  return index;
54 }
55 #elif defined(Vc_ICC)
56 // for all I know ICC supports the _bit_scan_* intrinsics
57 #else
58 // just assume the compiler can do it
59 #endif
60 
61 
62 #endif // VC_COMMON_BITSCANINTRINSICS_H_