rochars / byte-data

 * to-bytes: convert bytes to numbers and strings.

 * Copyright (c) 2017 Rafael da Silva Rocha.

 * https://github.com/rochars/byte-data

 */

const pad = require("../src/byte-padding.js");

const endianness = require("endianness");

const writer = require("../src/write-bytes.js");

const bitDepths = require("../src/bit-depth.js");

/**

 * Turn numbers and strings to bytes.

 * @param {!Array<number>|string} numbers float64 numbers.

 * @param {number} bitDepth The desired bitDepth for the data.

 * @param {Object} params The params. defaults to:

 *   - "float", defaults to false, true for floats.

 *       float is available for 16, 32 and 64 bit depths.

 *   - "base", defaults to 10, can be 2, 10 or 16

 *   - "char", defaults to false, true for strings

 *   - "be", defaults to false, true for big endian

 * @return {!Array<number>} the bytes.

 */

function toBytes(numbers, bitDepth, params={}) {

    let base = 10;

    if ("base" in params) {

        base = params.base;

    }

    let isBigEndian = params.be;

    let isChar = params.char;

    let isFloat = params.float;

    let bytes = writeBytes(numbers, isChar, isFloat, isBigEndian, bitDepth);

    outputToBase(bytes, bitDepth, base);

    return bytes;

}

/**

 * Turn the output to the correct base.

 * @param {!Array<number>} bytes The bytes.

 * @param {number} bitDepth The bitDepth of the data.

 * @param {number} base The base.

 */

function outputToBase(bytes, bitDepth, base) {

    if (bitDepth == 4) {

        bytesToBase(bytes, base, pad.paddingNibble);

    } else if (bitDepth == 2) {

        bytesToBase(bytes, base, pad.paddingCrumb);

    } else if(bitDepth == 1) {

        bytesToBase(bytes, base);

    }

}

/**

 * Write values as bytes.

 * @param {!Array<number>|string} numbers The values.

 * @param {boolean} isChar True if it is a string.

 * @param {boolean} isFloat True if it is a IEEE floating point number.

 * @param {boolean} isBigEndian True if the bytes should be big enadian.

 * @param {number} bitDepth The bitDepth of the data.

 * @return {!Array<number>} the bytes.

 */

function writeBytes(numbers, isChar, isFloat, isBigEndian, bitDepth) {

    let bitWriter;

    if (isChar) {

        bitWriter = writer.writeString;

    } else {

        bitWriter = writer['write' + bitDepth + 'Bit' + (isFloat ? "Float" : "")];

    }

    let i = 0;

    let j = 0;

    let len = numbers.length;

    let bytes = [];

    while (i < len) {            

        j = bitWriter(bytes, numbers, i, j);

        i++;

    }

    if (isBigEndian) {

        endianness.endianness(bytes, bitDepths.bitDepthOffsets[bitDepth]);

    }

    return bytes;

}

/**

 * Turn bytes to base.

 * @param {!Array<string>|!Array<number>} bytes The bytes.

 * @param {number} base The base.

 * @param {Function} padFunction The function to use for padding.

 */

function bytesToBase(bytes, base, padFunction=pad.padding) {

    if (base != 10) {

        let i = 0;

        let len = bytes.length;

        while (i < len) {

            bytes[i] = bytes[i].toString(base);

            padFunction(bytes, base, i);

            i++;

        }

    }

}

module.exports.toBytes = toBytes;