| <!DOCTYPE html> |
| <!-- |
| Copyright 2016 The Chromium Authors. All rights reserved. |
| Use of this source code is governed by a BSD-style license that can be |
| found in the LICENSE file. |
| --> |
| |
| <link rel="import" href="/tracing/base/iteration_helpers.html"> |
| |
| <script> |
| 'use strict'; |
| |
| var GREEK_SMALL_LETTER_MU = String.fromCharCode(956); |
| |
| tr.exportTo('tr.b', function() { |
| |
| var UnitScale = {}; |
| |
| function defineUnitScale(name, prefixes) { |
| if (UnitScale[name] !== undefined) |
| throw new Error('Unit scale \'' + name + '\' already exists'); |
| if (prefixes.AUTO !== undefined) { |
| throw new Error('\'AUTO\' unit prefix will be added automatically ' + |
| 'for unit scale \'' + name + '\''); |
| } |
| |
| // If the 'AUTO' unit prefix is used, the prefix that results in |
| // the absolute formatted value being as close to the [1, 1024) interval as |
| // possible is used. Example: 1023 and 1024 bytes are displayed as |
| // "1,023.0 B" and "1.0 KiB", respectively. |
| prefixes.AUTO = tr.b.dictionaryValues(prefixes); |
| prefixes.AUTO.sort((a, b) => a.value - b.value); |
| |
| UnitScale[name] = prefixes; |
| } |
| |
| /** |
| * Converts |value| from |fromPrefix| (e.g. kilo) to |toPrefix| (e.g. mega). |
| * |
| * Returns undefined if |value| is undefined. |
| * |fromPrefix| and |toPrefix| need not come from the same UnitScale. |
| * |
| * @param {(undefined|number)} value |
| * @param {!object} fromPrefix |
| * @param {!object} toPrefix |
| * @return {(undefined|number)} |
| */ |
| function convertUnit(value, fromPrefix, toPrefix) { |
| if (value === undefined) |
| return undefined; |
| return value * (fromPrefix.value / toPrefix.value); |
| } |
| |
| // See https://en.wikipedia.org/wiki/Binary_prefix. |
| defineUnitScale('Binary', { |
| NONE: { value: Math.pow(1024, 0), symbol: '' }, |
| KIBI: { value: Math.pow(1024, 1), symbol: 'Ki' }, |
| MEBI: { value: Math.pow(1024, 2), symbol: 'Mi' }, |
| GIBI: { value: Math.pow(1024, 3), symbol: 'Gi' }, |
| TEBI: { value: Math.pow(1024, 4), symbol: 'Ti' } |
| }); |
| |
| // See https://en.wikipedia.org/wiki/Metric_prefix. |
| defineUnitScale('Metric', { |
| NANO: { value: 1e-9, symbol: 'n' }, |
| MICRO: { value: 1e-6, symbol: GREEK_SMALL_LETTER_MU }, |
| MILLI: { value: 1e-3, symbol: 'm' }, |
| NONE: { value: 1, symbol: ''}, |
| KILO: { value: 1e3, symbol: 'k'}, |
| MEGA: { value: 1e6, symbol: 'M'}, |
| GIGA: { value: 1e9, symbol: 'G'} |
| }); |
| |
| return { |
| UnitScale: UnitScale, |
| convertUnit: convertUnit |
| }; |
| }); |
| </script> |
