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deeplearning4j--deeplearning4j/libnd4j/include/ops/declarable/helpers/impl/rnn.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 (iuriish@yahoo.com), created on 16.04.2018
//
#include <system/op_boilerplate.h>
#if NOT_EXCLUDED(OP_rnn)
// function nnCell implements an Elman RNN cell: output = activation(Wx*x + bx + Wh*ht + bh)
#include <helpers/BlasHelper.h>
#include <ops/declarable/helpers/rnn.h>
namespace sd {
namespace ops {
namespace helpers {
//////////////////////////////////////////////////////////////////////////
void rnnCell(sd::LaunchContext* context, NDArray* xt, NDArray* Wx, NDArray* Wh, NDArray* b,
NDArray* hPrev, NDArray* ht) {
// xt input [bS x iS]
// Wx input-to-hidden weights, [iS x nU]
// Wh hidden-to-hidden weights, [nU x nU]
// b biases, [2*nU]: {0, nU} are input-to-hidden biases and {nU, 2*nU} are hidden-to-hidden biases
// hPrev previous cell output [bS x nU], that is at previous time step t-1, in case of projection=false -> nU=nU!!!
const int nU = hPrev->sizeAt(1);
// ht is current cell output [bS x nU], that is at current time step t
NDArray *bFirst = (*b)({{0, nU}});
NDArray *bSecond = (*b)({{nU, 2 * nU}});
NDArray *mmulOne = mmul(*xt, *Wx);
NDArray *mmulTwo = mmul(*hPrev, *Wh);
// Chain additions with proper dereferencing since operators return NDArray*
NDArray *temp1 = (*mmulOne) + (*bFirst);
NDArray *temp2 = (*temp1) + (*mmulTwo);
NDArray *temp3 = (*temp2) + (*bSecond);
ht->assign(temp3); // [bS x nU] + [nU] + [bS x nU] + [nU] = [bS x nU]
ht->applyTransform(transform::Tanh, ht);
// Clean up intermediate results
delete temp1;
delete temp2;
delete temp3;
delete mmulOne;
delete mmulTwo;
delete bFirst;
delete bSecond;
}
//////////////////////////////////////////////////////////////////////////
void rnnTimeLoop(sd::LaunchContext* context, NDArray* x, NDArray* Wx, NDArray* Wh, NDArray* b,
NDArray* h0, NDArray* maxTimeStep, NDArray* h, NDArray* hFinal) {
// x input [time x bS x iS]
// Wx input-to-hidden weights, [iS x nU]
// Wh hidden-to-hidden weights, [nU x nU]
// b biases for, [2*nU]
// h0 initial cell output (at time step = 0) [bS x nU]
// maxTimeStep vector [bS] containing integer values within [0,time), each element of this vector set max time step
// per each input in batch, this means there are no calculations for time >= maxTimeStep
const int time = x->sizeAt(0);
const int bS = x->sizeAt(1);
// at first time step
if (h0)
hFinal->assign(h0);
else
*hFinal = 0.;
BlasHelper::getInstance(); // to avoid memory leak in pragma parallel loops
// loop through batch of inputs
for (int e = 0; e < bS; ++e) {
// loop through time steps
for (int t = 0; t < time; ++t) {
int maxStep = maxTimeStep ? maxTimeStep->e<int>(e) : time;
NDArray *xt = (*x)({t, t + 1, e, e + 1, 0, 0}, true);
NDArray *ht = (*h)({t, t + 1, e, e + 1, 0, 0}, true);
NDArray *hPrev = (*hFinal)({e, e + 1, 0, 0}, true); // previous state
if (t >= maxStep) {
*ht = 0.;
NDArray *hPrevAssign = (*h)({maxStep - 1, maxStep, e, e + 1, 0, 0});
if (maxStep != 0) hPrev->assign(hPrevAssign);
delete hPrevAssign;
} else {
helpers::rnnCell(context, xt, Wx, Wh, b, hPrev, ht);
hPrev->assign(ht);
}
delete xt;
delete ht;
delete hPrev;
}
}
}
} // namespace helpers
} // namespace ops
} // namespace sd
#endif