@tonejs/midi/src/BinarySearch.ts

Convert binary midi into JSON

/**
 * Return the index of the element at or before the given property
 * @hidden
 */
export function search(array: any[], value: any, prop = "ticks"): number {
	let beginning = 0;
	const len = array.length;
	let end = len;
	if (len > 0 && array[len - 1][prop] <= value) {
		return len - 1;
	}
	while (beginning < end) {
		// calculate the midpoint for roughly equal partition
		let midPoint = Math.floor(beginning + (end - beginning) / 2);
		const event = array[midPoint];
		const nextEvent = array[midPoint + 1];
		if (event[prop] === value) {
			// choose the last one that has the same value
			for (let i = midPoint; i < array.length; i++) {
				const testEvent = array[i];
				if (testEvent[prop] === value) {
					midPoint = i;
				}
			}
			return midPoint;
		} else if (event[prop] < value && nextEvent[prop] > value) {
			return midPoint;
		} else if (event[prop] > value) {
			// search lower
			end = midPoint;
		} else if (event[prop] < value) {
			// search upper
			beginning = midPoint + 1;
		}
	}
	return -1;
}

/**
 * Does a binary search to insert the note
 * in the correct spot in the array
 * @hidden
 */
export function insert(array: any[], event: object, prop = "ticks"): void {
	if (array.length) {
		const index = search(array, event[prop], prop);
		array.splice(index + 1, 0, event);
	} else {
		array.push(event);
	}
}