def signedLongToUnsignedLong(signedLong: Long): BigInt = {
  BigInt(signedLong & 0xFFFFFFFFFFFFFFFFL)
}

// 使用示例
val signedLong1: Long = 1234567890123456789L
val unsignedLong1: BigInt = signedLongToUnsignedLong(signedLong1)
println(unsignedLong1) // 输出: 1234567890123456789

val signedLong2: Long = -1234567890123456789L
val unsignedLong2: BigInt = signedLongToUnsignedLong(signedLong2)
println(unsignedLong2) // 输出: 17202172649742383127 (这是-1234567890123456789作为无符号整数的值)