88 lines
2.0 KiB
JavaScript
88 lines
2.0 KiB
JavaScript
|
/**
|
||
|
|
* @license Apache-2.0
|
||
|
|
*
|
||
|
|
* Copyright (c) 2018 The Stdlib Authors.
|
||
|
|
*
|
||
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
||
|
|
* you may not use this file except in compliance with the License.
|
||
|
|
* You may obtain a copy of the License at
|
||
|
|
*
|
||
|
|
* http://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.
|
||
|
|
*/
|
||
|
|
|
||
|
|
'use strict';
|
||
|
|
|
||
|
|
// MAIN //
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Computes the minimum and maximum linear indices in an underlying data buffer which are accessible to an array view.
|
||
|
|
*
|
||
|
|
* @param {NonNegativeIntegerArray} shape - array shape
|
||
|
|
* @param {IntegerArray} strides - stride array
|
||
|
|
* @param {NonNegativeInteger} offset - index offset
|
||
|
|
* @returns {Array} linear indices
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* var shape = [ 10, 10 ];
|
||
|
|
* var strides = [ 10, 1 ];
|
||
|
|
* var offset = 10;
|
||
|
|
*
|
||
|
|
* var idx = minmaxViewBufferIndex( shape, strides, offset );
|
||
|
|
* // returns [ 10, 109 ]
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* var shape = [ 10, 10 ];
|
||
|
|
* var strides = [ -10, -1 ];
|
||
|
|
* var offset = 99;
|
||
|
|
*
|
||
|
|
* var idx = minmaxViewBufferIndex( shape, strides, offset );
|
||
|
|
* // returns [ 0, 99 ]
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* var shape = [ 10, 10 ];
|
||
|
|
* var strides = [ 1, 10 ];
|
||
|
|
* var offset = 10;
|
||
|
|
*
|
||
|
|
* var idx = minmaxViewBufferIndex( shape, strides, offset );
|
||
|
|
* // returns [ 10, 109 ]
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* var shape = [ 10, 10 ];
|
||
|
|
* var strides = [ -1, -10 ];
|
||
|
|
* var offset = 99;
|
||
|
|
*
|
||
|
|
* var idx = minmaxViewBufferIndex( shape, strides, offset );
|
||
|
|
* // returns [ 0, 99 ]
|
||
|
|
*/
|
||
|
|
function minmaxViewBufferIndex( shape, strides, offset ) {
|
||
|
|
var ndims;
|
||
|
|
var min;
|
||
|
|
var max;
|
||
|
|
var s;
|
||
|
|
var i;
|
||
|
|
|
||
|
|
ndims = shape.length;
|
||
|
|
min = offset;
|
||
|
|
max = offset;
|
||
|
|
for ( i = 0; i < ndims; i++ ) {
|
||
|
|
s = strides[ i ];
|
||
|
|
if ( s > 0 ) {
|
||
|
|
max += s * ( shape[i]-1 );
|
||
|
|
} else if ( s < 0 ) {
|
||
|
|
min += s * ( shape[i]-1 ); // decrements min
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return [ min, max ];
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
// EXPORTS //
|
||
|
|
|
||
|
|
module.exports = minmaxViewBufferIndex;
|