98 lines
3.6 KiB
C++
98 lines
3.6 KiB
C++
/*******************************************************************************
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* Copyright (c) 2015-2018 Skymind, Inc.
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*
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* This program and the accompanying materials are made available under the
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* terms of the Apache License, Version 2.0 which is available at
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* https://www.apache.org/licenses/LICENSE-2.0.
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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* SPDX-License-Identifier: Apache-2.0
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******************************************************************************/
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//
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// @author Yurii Shyrma (iuriish@yahoo.com), created on 16.04.2018
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//
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// function nnCell implements an Elman RNN cell: output = activation(Wx*x + bx + Wh*ht + bh)
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#include<ops/declarable/helpers/rnn.h>
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#include <helpers/BlasHelper.h>
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namespace nd4j {
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namespace ops {
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namespace helpers {
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//////////////////////////////////////////////////////////////////////////
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void rnnCell(nd4j::LaunchContext * context, const NDArray* xt, const NDArray* Wx, const NDArray* Wh, const NDArray* b, const NDArray* hPrev, NDArray* ht) {
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// xt input [bS x iS]
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// Wx input-to-hidden weights, [iS x nU]
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// Wh hidden-to-hidden weights, [nU x nU]
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// b biases, [2*nU]: {0, nU} are input-to-hidden biases and {nU, 2*nU} are hidden-to-hidden biases
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// hPrev previous cell output [bS x nU], that is at previous time step t-1, in case of projection=false -> nU=nU!!!
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const int nU = hPrev->sizeAt(1);
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// ht is current cell output [bS x nU], that is at current time step t
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ht->assign(mmul(*xt, *Wx) + (*b)({{0, nU}}) + mmul(*hPrev, *Wh) + (*b)({{nU, 2*nU}})); // [bS x nU] + [nU] + [bS x nU] + [nU] = [bS x nU]
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ht->applyTransform(transform::Tanh);
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}
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//////////////////////////////////////////////////////////////////////////
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void rnnTimeLoop(nd4j::LaunchContext * context, const NDArray* x, const NDArray* Wx, const NDArray* Wh, const NDArray* b, const NDArray* h0, const NDArray* maxTimeStep, NDArray* h, NDArray* hFinal) {
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// x input [time x bS x iS]
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// Wx input-to-hidden weights, [iS x nU]
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// Wh hidden-to-hidden weights, [nU x nU]
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// b biases for, [2*nU]
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// h0 initial cell output (at time step = 0) [bS x nU]
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// 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
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const int time = x->sizeAt(0);
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const int bS = x->sizeAt(1);
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// at first time step
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if(h0)
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hFinal->assign(h0);
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else
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*hFinal = 0.;
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BlasHelper::getInstance(); // to avoid memory leak in pragma parallel loops
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// loop through batch of inputs
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for (int e = 0; e < bS; ++e) {
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// loop through time steps
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for (int t = 0; t < time; ++t) {
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int maxStep = maxTimeStep ? maxTimeStep->e<int>(e) : time;
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auto xt = (*x)({t,t+1, e,e+1, 0,0}, true);
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auto ht = (*h)({t,t+1, e,e+1, 0,0}, true);
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auto hPrev = (*hFinal)({e,e+1, 0,0}, true); // previous state
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if(t >= maxStep) {
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ht = 0.;
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if(maxStep != 0)
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hPrev.assign((*h)({maxStep-1,maxStep, e,e+1, 0,0}));
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}
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else {
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helpers::rnnCell(context, &xt, Wx, Wh, b, &hPrev, &ht);
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hPrev.assign(ht);
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}
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}
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}
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}
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}
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}
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}
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