82 lines
1.9 KiB
JavaScript
82 lines
1.9 KiB
JavaScript
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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://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,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MAIN //
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/**
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* Computes the minimum linear index in an underlying data buffer accessible to an array view.
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*
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* @param {NonNegativeIntegerArray} shape - array shape
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* @param {IntegerArray} strides - stride array
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* @param {NonNegativeInteger} offset - index offset
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* @returns {NonNegativeInteger} linear index
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*
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* @example
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* var shape = [ 10, 10 ];
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* var strides = [ 10, 1 ];
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* var offset = 10;
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*
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* var idx = minViewBufferIndex( shape, strides, offset );
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* // returns 10
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*
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* @example
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* var shape = [ 10, 10 ];
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* var strides = [ -10, -1 ];
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* var offset = 109;
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*
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* var idx = minViewBufferIndex( shape, strides, offset );
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* // returns 10
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*
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* @example
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* var shape = [ 10, 10 ];
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* var strides = [ 1, 10 ];
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* var offset = 10;
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*
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* var idx = minViewBufferIndex( shape, strides, offset );
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* // returns 10
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*
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* @example
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* var shape = [ 10, 10 ];
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* var strides = [ -1, -10 ];
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* var offset = 109;
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*
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* var idx = minViewBufferIndex( shape, strides, offset );
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* // returns 10
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*/
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function minViewBufferIndex( shape, strides, offset ) {
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var ndims;
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var idx;
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var i;
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ndims = shape.length;
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idx = offset;
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for ( i = 0; i < ndims; i++ ) {
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if ( strides[ i ] < 0 ) {
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idx += strides[ i ] * (shape[ i ] - 1); // decrements the index
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}
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}
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return idx;
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}
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// EXPORTS //
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module.exports = minViewBufferIndex;
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