/usr/include/thrust/detail/integer_math.h is in libthrust-dev 1.8.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 | /*
* Copyright 2008-2013 NVIDIA Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <thrust/detail/config.h>
#include <limits>
namespace thrust
{
namespace detail
{
template<typename Integer>
__host__ __device__ __thrust_forceinline__
Integer clz(Integer x)
{
// XXX optimize by lowering to intrinsics
int num_bits = 8 * sizeof(Integer);
int num_bits_minus_one = num_bits - 1;
for(int i = num_bits_minus_one; i >= 0; --i)
{
if((Integer(1) << i) & x)
{
return num_bits_minus_one - i;
}
}
return num_bits;
}
template<typename Integer>
__host__ __device__ __thrust_forceinline__
bool is_power_of_2(Integer x)
{
return 0 == (x & (x - 1));
}
template<typename Integer>
__host__ __device__ __thrust_forceinline__
Integer log2(Integer x)
{
Integer num_bits = 8 * sizeof(Integer);
Integer num_bits_minus_one = num_bits - 1;
return num_bits_minus_one - clz(x);
}
template<typename Integer>
__host__ __device__ __thrust_forceinline__
Integer log2_ri(Integer x)
{
Integer result = log2(x);
// this is where we round up to the nearest log
if(!is_power_of_2(x))
{
++result;
}
return result;
}
template<typename Integer>
__host__ __device__ __thrust_forceinline__
bool is_odd(Integer x)
{
return 1 & x;
}
} // end detail
} // end thrust
|