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deeplearning4j--deeplearning4j/libnd4j/include/ops/declarable/helpers/cpu/ismax.cpp
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2026-07-13 12:47:05 +08:00

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/* ******************************************************************************
*
*
* 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.
*
* See the NOTICE file distributed with this work for additional
* information regarding copyright ownership.
* 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 Yurii Shyrma, created on 21.09.2018
// @author raver119@gmail.com
//
// CPU implementation of ismax helper
//
#include <execution/Threads.h>
#include <helpers/ConstantTadHelper.h>
#include <ops/declarable/helpers/ismax.h>
#include <system/op_boilerplate.h>
namespace sd {
namespace ops {
namespace helpers {
template <typename T>
static void ismax_(LaunchContext* context, NDArray* input, NDArray* output,
const std::vector<LongType>& dimensions) {
// Initialize output to zeros
output->nullify();
if (dimensions.size() == 0 || (dimensions.size() == 1 && dimensions[0] == sd::DataTypeUtils::max<int>())) {
// Scalar case - find the single maximum in the entire array
auto indexMax = input->applyIndexReduce(indexreduce::IndexMax, &dimensions);
auto targetIdx = indexMax->e<LongType>(0);
// Set the maximum position to 1
output->p(targetIdx, static_cast<T>(1));
delete indexMax;
} else {
// Dimensional case - find maximum along specified dimensions
std::vector<LongType> copy(dimensions);
// Get the indices of maximum values along the specified dimensions
auto indexMaxArr = input->applyIndexReduce(indexreduce::IndexMax, &dimensions);
// Get TAD information for the output
auto packZ = ConstantTadHelper::getInstance().tadForDimensions(output->shapeInfo(), copy.data(), copy.size());
auto zTadShapeInfo = packZ->primaryShapeInfo();
auto zTadOffsets = packZ->primaryOffsets();
auto numTads = packZ->numberOfTads();
auto tadLen = shape::length(zTadShapeInfo);
auto zBuffer = output->bufferAsT<T>();
// For each TAD, set the maximum index position to 1
auto func = PRAGMA_THREADS_FOR {
for (auto t = start; t < stop; t++) {
auto zTadOffset = zTadOffsets[t];
auto maxIdx = indexMaxArr->e<LongType>(t);
// Calculate the actual offset within this TAD
if (maxIdx >= 0 && maxIdx < tadLen) {
sd::LongType coords[SD_MAX_RANK];
sd::LongType zOffset;
const int tadRank = shape::rank(zTadShapeInfo);
const sd::LongType* tadShape = shape::shapeOf(zTadShapeInfo);
const sd::LongType* tadStride = shape::stride(zTadShapeInfo);
INDEX2COORDS(maxIdx, tadRank, tadShape, coords);
COORDS2INDEX(tadRank, tadStride, coords, zOffset);
zBuffer[zTadOffset + zOffset] = static_cast<T>(1);
}
}
};
samediff::Threads::parallel_for(func, 0, numTads);
delete indexMaxArr;
}
}
void ismax(LaunchContext* context, NDArray* input, NDArray* output, const std::vector<LongType>& dimensions) {
NDArray::prepareSpecialUse({output}, {input});
BUILD_SINGLE_SELECTOR(input->dataType(), ismax_, (context, input, output, dimensions), SD_COMMON_TYPES);
NDArray::registerSpecialUse({output}, {input});
}
BUILD_SINGLE_TEMPLATE(void ismax_,
(sd::LaunchContext* context, NDArray* input, NDArray* output,
const std::vector<sd::LongType>& dimensions),
SD_COMMON_TYPES);
} // namespace helpers
} // namespace ops
} // namespace sd