canopen
Version:
CANopen implementation for Javascript
145 lines (133 loc) • 4.3 kB
JavaScript
const { DataType } = require('../types');
const { dateToTime } = require('./date');
/**
* Convert a string to a Buffer.
*
* @param {string} value - data to convert.
* @returns {Buffer} converted Buffer.
* @private
*/
function stringToRaw(value) {
let raw = (value) ? Buffer.from(value) : Buffer.alloc(0);
const end = raw.indexOf('\0');
if (end != -1)
raw = raw.subarray(0, end);
return raw;
}
/**
* Convert a Date to a Buffer.
*
* @param {Date} value - data to convert.
* @returns {Buffer} converted Buffer.
* @private
*/
function dateToRaw(value) {
const raw = Buffer.alloc(6);
const { days, ms } = dateToTime(value);
raw.writeUInt16LE(days, 4);
raw.writeUInt32LE(ms, 0);
return raw;
}
/**
* Convert a value to a Buffer based on type.
*
* @param {number | bigint | string | Date} value - data to convert.
* @param {DataType | string} type - how to interpret the data.
* @param {number} [scaleFactor] - optional multiplier for numeric types.
* @returns {Buffer} converted Buffer.
*/
function typeToRaw(value, type, scaleFactor=1.0) {
if (value === undefined || value === null)
value = 0;
if (typeof type === 'string')
type = DataType[type];
let raw;
switch (type) {
case DataType.BOOLEAN:
raw = Buffer.from(value ? [1] : [0]);
break;
case DataType.INTEGER8:
raw = Buffer.alloc(1);
raw.writeInt8(value / scaleFactor);
break;
case DataType.UNSIGNED8:
raw = Buffer.alloc(1);
raw.writeUInt8(value / scaleFactor);
break;
case DataType.INTEGER16:
raw = Buffer.alloc(2);
raw.writeInt16LE(value / scaleFactor);
break;
case DataType.UNSIGNED16:
raw = Buffer.alloc(2);
raw.writeUInt16LE(value / scaleFactor);
break;
case DataType.INTEGER24:
raw = Buffer.alloc(3);
raw.writeIntLE(value / scaleFactor, 0, 3);
break;
case DataType.UNSIGNED24:
raw = Buffer.alloc(3);
raw.writeUIntLE(value / scaleFactor, 0, 3);
break;
case DataType.INTEGER32:
raw = Buffer.alloc(4);
raw.writeInt32LE(value / scaleFactor);
break;
case DataType.UNSIGNED32:
raw = Buffer.alloc(4);
raw.writeUInt32LE(value / scaleFactor);
break;
case DataType.INTEGER40:
raw = Buffer.alloc(5);
raw.writeIntLE(value / scaleFactor, 0, 5);
break;
case DataType.UNSIGNED40:
raw = Buffer.alloc(5);
raw.writeUIntLE(value / scaleFactor, 0, 5);
break;
case DataType.INTEGER48:
raw = Buffer.alloc(6);
raw.writeIntLE(value / scaleFactor, 0, 6);
break;
case DataType.UNSIGNED48:
raw = Buffer.alloc(6);
raw.writeUIntLE(value / scaleFactor, 0, 6);
break;
case DataType.INTEGER56:
case DataType.INTEGER64:
if (typeof value != 'bigint')
value = BigInt(value);
raw = Buffer.alloc(8);
raw.writeBigInt64LE(value / BigInt(scaleFactor));
break;
case DataType.UNSIGNED56:
case DataType.UNSIGNED64:
if (typeof value != 'bigint')
value = BigInt(value);
raw = Buffer.alloc(8);
raw.writeBigUInt64LE(value / BigInt(scaleFactor));
break;
case DataType.REAL32:
raw = Buffer.alloc(4);
raw.writeFloatLE(value / scaleFactor);
break;
case DataType.REAL64:
raw = Buffer.alloc(8);
raw.writeDoubleLE(value / scaleFactor);
break;
case DataType.VISIBLE_STRING:
raw = stringToRaw(value);
break;
case DataType.OCTET_STRING:
case DataType.UNICODE_STRING:
raw = (value) ? Buffer.from(value) : Buffer.alloc(0);
break;
case DataType.TIME_OF_DAY:
case DataType.TIME_DIFFERENCE:
raw = dateToRaw(value);
break;
}
return raw;
}
module.exports = exports = typeToRaw;