time-to-botec

Benchmark sampling in different programming languages
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main.js (3169B)

      1 /**
      2 * @license Apache-2.0
      3 *
      4 * Copyright (c) 2018 The Stdlib Authors.
      5 *
      6 * Licensed under the Apache License, Version 2.0 (the "License");
      7 * you may not use this file except in compliance with the License.
      8 * You may obtain a copy of the License at
      9 *
     10 *    http://www.apache.org/licenses/LICENSE-2.0
     11 *
     12 * Unless required by applicable law or agreed to in writing, software
     13 * distributed under the License is distributed on an "AS IS" BASIS,
     14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     15 * See the License for the specific language governing permissions and
     16 * limitations under the License.
     17 */
     18 
     19 'use strict';
     20 
     21 // MAIN //
     22 
     23 /**
     24 * Converts a linear index in an array view to a linear index in an underlying data buffer.
     25 *
     26 * @param {NonNegativeIntegerArray} shape - array shape
     27 * @param {IntegerArray} strides - stride array
     28 * @param {NonNegativeInteger} offset - location of the first indexed value **based** on the stride array
     29 * @param {string} order - specifies whether an array is row-major (C-style) or column-major (Fortran-style)
     30 * @param {integer} idx - linear index in an array view
     31 * @param {string} mode - specifies how to handle a linear index which exceeds array dimensions
     32 * @throws {RangeError} linear index must not exceed array dimensions
     33 * @returns {NonNegativeInteger} linear index in an underlying data buffer
     34 *
     35 * @example
     36 * var shape = [ 3, 3 ];
     37 * var strides = [ -3, 1 ];
     38 * var offset = 6;
     39 * var order = 'row-major';
     40 * var mode = 'throw';
     41 *
     42 * var ind = vind2bind( shape, strides, offset, order, 1, mode );
     43 * // returns 7
     44 */
     45 function vind2bind( shape, strides, offset, order, idx, mode ) {
     46 	var ndims;
     47 	var len;
     48 	var ind;
     49 	var s;
     50 	var i;
     51 
     52 	ndims = shape.length;
     53 	len = 1;
     54 	for ( i = 0; i < ndims; i++ ) {
     55 		len *= shape[ i ];
     56 	}
     57 	if ( mode === 'clamp' ) {
     58 		if ( idx < 0 ) {
     59 			idx = 0;
     60 		} else if ( idx >= len ) {
     61 			idx = len - 1;
     62 		}
     63 	} else if ( mode === 'wrap' ) {
     64 		if ( idx < 0 ) {
     65 			idx += len; // slight optimization to avoid modulo arithmetic when |idx| <= len
     66 			if ( idx < 0 ) {
     67 				idx %= len;
     68 				if ( idx !== 0 ) {
     69 					idx += len;
     70 				}
     71 			}
     72 		} else if ( idx >= len ) {
     73 			idx -= len; // slight optimization to avoid modulo arithmetic when len < idx <= 2*len
     74 			if ( idx >= len ) {
     75 				idx %= len;
     76 			}
     77 		}
     78 	} else if ( idx < 0 || idx >= len ) {
     79 		throw new RangeError( 'invalid argument. Linear index must not exceed array dimensions. Number of array elements: ' + len + '. Value: `' + idx + '`.' );
     80 	}
     81 	// Trivial case where the offset into the underlying data buffer is 0...
     82 	if ( offset === 0 ) {
     83 		return idx;
     84 	}
     85 	// The approach which follows is to resolve a view index to its subscripts and then plug the subscripts into the standard formula for computing the linear index in the underlying data buffer...
     86 	ind = offset;
     87 	if ( order === 'column-major' ) {
     88 		for ( i = 0; i < ndims; i++ ) {
     89 			s = idx % shape[ i ];
     90 			idx -= s;
     91 			idx /= shape[ i ];
     92 			ind += s * strides[ i ];
     93 		}
     94 		return ind;
     95 	}
     96 	// Case: row-major
     97 	for ( i = ndims-1; i >= 0; i-- ) {
     98 		s = idx % shape[ i ];
     99 		idx -= s;
    100 		idx /= shape[ i ];
    101 		ind += s * strides[ i ];
    102 	}
    103 	return ind;
    104 }
    105 
    106 
    107 // EXPORTS //
    108 
    109 module.exports = vind2bind;