function sync_by_filter_block(block, count, buf, bloom_blocktx, result_callback) {
	for (let j = 0; j < count; j++) {
		let w = new DataView(buf);
		w.setInt32(4, j);
		const r = new Uint8Array(buf);
		bloom_blocktx.check(r).then(function(ok) {
			if (ok) {
				// console.debug('match in block' + block + ' tx ' + j);
				result_callback(block, j);
			}
		});
	}
}

function sync_by_filter(caller, lo, hi, bloom_block, bloom_blocktx, tx_count_getter, result_callback) {
	for (let i = lo; i <= hi; i++) {
		let a = new ArrayBuffer(8);
		let w = new DataView(a);
		w.setInt32(0, i);
		const r = new Uint8Array(a.slice(0, 4));
		bloom_block.check(r).then(function(ok) {
			if (ok) {
				// console.debug('match in block ' + i);
				tx_count_getter(i).then(function(n) {
					sync_by_filter_block(i, n, a, bloom_blocktx, result_callback);
				});
			}
		});
	}
}