cavis/libnd4j/include/ops/declarable/helpers/cpu/hamming.cpp

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/*******************************************************************************
* Copyright (c) 2015-2018 Skymind, Inc.
*
* This program and the accompanying materials are made available under the
* terms of the Apache License, Version 2.0 which is available at
* https://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.
*
* SPDX-License-Identifier: Apache-2.0
******************************************************************************/
//
// @author raver119@gmail.com
//
#include <ops/declarable/helpers/helpers.h>
#include <ops/declarable/helpers/hamming.h>
#include <execution/Threads.h>
namespace nd4j {
namespace ops {
namespace helpers {
static Nd4jLong hamming_distance(unsigned long long x, unsigned long long y) {
Nd4jLong dist = 0;
for (unsigned long long val = x ^ y; val > 0; val /= 2) {
if (val & 1)
dist++;
}
return dist;
}
template <typename X, typename Z>
static void _hamming(NDArray &x, NDArray &y, NDArray &z) {
auto xEws = x.ews();
auto yEws = y.ews();
auto xBuffer = x.bufferAsT<X>();
auto yBuffer = y.bufferAsT<X>();
Nd4jLong distance = 0;
auto lengthOf = x.lengthOf();
int maxThreads = nd4j::math::nd4j_min<int>(256, omp_get_max_threads());
Nd4jLong intermediate[256];
// nullify temp values
for (int e = 0; e < maxThreads; e++)
intermediate[e] = 0;
if (xEws == 1 && yEws == 1 && x.ordering() == y.ordering()) {
auto func = PRAGMA_THREADS_FOR {
for (auto e = start; e < stop; e += increment) {
auto _x = static_cast<unsigned long long>(xBuffer[e]);
auto _y = static_cast<unsigned long long>(yBuffer[e]);
intermediate[thread_id] += hamming_distance(_x, _y);
}
};
maxThreads = samediff::Threads::parallel_for(func, 0, lengthOf);
} else if (xEws > 1 && yEws > 1 && x.ordering() == y.ordering()) {
auto func = PRAGMA_THREADS_FOR {
for (auto e = start; e < stop; e += increment) {
auto _x = static_cast<unsigned long long>(xBuffer[e * xEws]);
auto _y = static_cast<unsigned long long>(yBuffer[e * yEws]);
intermediate[thread_id] += hamming_distance(_x, _y);
}
};
maxThreads = samediff::Threads::parallel_for(func, 0, lengthOf);
} else {
auto func = PRAGMA_THREADS_FOR {
for (auto e = start; e < stop; e += increment) {
auto _x = static_cast<unsigned long long>(x.e<Nd4jLong>(e));
auto _y = static_cast<unsigned long long>(y.e<Nd4jLong>(e));
intermediate[thread_id] += hamming_distance(_x, _y);
}
};
maxThreads = samediff::Threads::parallel_for(func, 0, lengthOf);
}
// accumulate intermediate variables into output array
for (int e = 0; e < maxThreads; e++)
distance += intermediate[e];
z.p(0, distance);
}
void hamming(LaunchContext *context, NDArray &x, NDArray &y, NDArray &output) {
BUILD_DOUBLE_SELECTOR(x.dataType(), output.dataType(), _hamming, (x, y, output), INTEGER_TYPES, INDEXING_TYPES);
}
}
}
}