import 'dart:typed_data';

/// Calculates the NEG8 checksum for a buffer.
/// NEG8: start at 0, subtract each byte, keep lower 8 bits.
/// The result should match the last byte of a valid frame.
int calculateNeg8(Uint8List buf) {
  int neg8 = 0;
  for (int i = 0; i < buf.length; i++) {
    neg8 = (neg8 - buf[i]) & 0xFF;
  }
  return neg8;
}

/// Returns true if the frame's last byte equals the NEG8 of all preceding bytes.
bool validateFrame(Uint8List frame) {
  if (frame.isEmpty) return false;
  int neg8 = 0;
  for (int i = 0; i < frame.length - 1; i++) {
    neg8 = (neg8 - frame[i]) & 0xFF;
  }
  return neg8 == frame[frame.length - 1];
}