readIntLE function
Implementation
BigInt readIntLE(BufferPipe pipe, int byteLength) {
var val = readUIntLE(pipe, byteLength);
final mul = BigInt.from(2).pow(
(BigInt.from(8) * BigInt.from(byteLength - 1) + BigInt.from(7)).toInt());
if (val >= mul) {
val -= mul * BigInt.from(2);
}
return val;
}