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/**
* Reads VLQ From a MIDI byte array
* @param MIDIbyteArray {IndexedByteArray}
* @returns {number}
*/
export function readVariableLengthQuantity(MIDIbyteArray)
{
let out = 0;
while (MIDIbyteArray)
{
const byte = MIDIbyteArray[MIDIbyteArray.currentIndex++];
// extract the first 7 bytes
out = (out << 7) | (byte & 127);
// if the last byte isn't 1, stop reading
if ((byte >> 7) !== 1)
{
break;
}
}
return out;
}
/**
* Write a VLQ from a number to a byte array
* @param number {number}
* @returns {number[]}
*/
export function writeVariableLengthQuantity(number)
{
// Add the first byte
let bytes = [number & 127];
number >>= 7;
// Continue processing the remaining bytes
while (number > 0)
{
bytes.unshift((number & 127) | 128);
number >>= 7;
}
return bytes;
} |