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/* |
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* to-bytes: bytes to numbers and strings. |
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* Copyright (c) 2017 Rafael da Silva Rocha. |
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* https://github.com/rochars/byte-data |
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*/ |
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const writer = require("../src/write-bytes.js"); |
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const helpers = require("../src/helpers.js"); |
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const bitDepthLib = require("../src/bit-depth.js"); |
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/** |
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* Turn numbers and strings to bytes. |
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* @param {!Array<number>|number|string} values The data. |
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* @param {number} bitDepth The bit depth of the data. |
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* Possible values are 1, 2, 4, 8, 16, 24, 32, 40, 48 or 64. |
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* @param {Object} options The options: |
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* - "float": True for floating point numbers. Default is false. |
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* This option is available for 16, 32 and 64-bit numbers. |
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* - "signed": True for signed values. Default is false. |
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* - "base": The base of the output. Default is 10. Can be 2, 10 or 16. |
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* - "char": If the bytes represent a string. Default is false. |
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* - "be": If the values are big endian. Default is false (little endian). |
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* - "buffer": If the bytes should be returned as a Uint8Array. |
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* Default is false (bytes are returned as a regular array). |
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* @return {!Array<number>|!Array<string>|Uint8Array} the data as a byte buffer. |
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*/ |
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function toBytes(values, bitDepth, options={"base": 10, "signed": false}) { |
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if (bitDepth == 64) { |
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options.float = true; |
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} |
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if (options.float) { |
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options.signed = true; |
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} |
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options.bits = bitDepth; |
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values = helpers.turnToArray(values); |
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let bytes = writeBytes(values, options, bitDepth); |
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helpers.makeBigEndian(bytes, options.be, bitDepth); |
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helpers.outputToBase(bytes, bitDepth, options.base); |
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helpers.fixFloat16Endianness(bytes, options); |
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if (options.buffer) { |
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bytes = new Uint8Array(bytes); |
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} |
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return bytes; |
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} |
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/** |
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* Write values as bytes. |
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* @param {!Array<number>|number|string} values The data. |
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* @param {Object} options The options according to the type. |
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* @param {number} bitDepth The bitDepth of the data. |
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* @return {!Array<number>} the bytes. |
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*/ |
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function writeBytes(values, options, bitDepth) { |
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let bitWriter; |
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if (options.char) { |
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bitWriter = writer.writeString; |
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} else { |
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bitWriter = writer['write' + bitDepth + 'Bit' + (options.float ? "Float" : "")]; |
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} |
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let i = 0; |
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let j = 0; |
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let len = values.length; |
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let bytes = []; |
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let minMax = getBitDepthMinMax(options, bitDepth); |
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while (i < len) { |
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if (!options.float) { |
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checkOverflow(values, i, minMax.min, minMax.max); |
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} |
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j = bitWriter(bytes, values, i, j, options.signed); |
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i++; |
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} |
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return bytes; |
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} |
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/** |
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* Get the minimum and maximum values accordind to the type. |
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* @param {Object} options The options according to the type. |
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* @param {number} bitDepth The bit depth of the data. |
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* @return {Object} |
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*/ |
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function getBitDepthMinMax(options, bitDepth) { |
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let minMax = {}; |
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if (options.signed) { |
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minMax.max = (bitDepthLib.BitDepthMaxValues[bitDepth] / 2) - 1; |
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minMax.min = (bitDepthLib.BitDepthMaxValues[bitDepth] / 2) * -1; |
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} else { |
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minMax.max = bitDepthLib.BitDepthMaxValues[bitDepth] - 1; |
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minMax.min = 0; |
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} |
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return minMax; |
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} |
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/** |
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* Limit the value according to the bit depth in case of |
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* overflow or underflow. |
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* @param {!Array<number>|number|string} values The data. |
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* @param {number} index The index of the value in the array. |
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* @param {number} min The minimum value. |
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* @param {number} max The maximum value. |
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*/ |
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function checkOverflow(values, index, min, max) { |
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if (values[index] > max) { |
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values[index] = max; |
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} else if(values[index] < min) { |
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values[index] = min; |
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} |
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} |
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module.exports.toBytes = toBytes; |
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rochars /
byte-data
