23 lines
669 B
Dart
23 lines
669 B
Dart
import 'dart:typed_data';
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/// Calculates the NEG8 checksum for a buffer.
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/// NEG8: start at 0, subtract each byte, keep lower 8 bits.
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/// The result should match the last byte of a valid frame.
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int calculateNeg8(Uint8List buf) {
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int neg8 = 0;
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for (int i = 0; i < buf.length; i++) {
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neg8 = (neg8 - buf[i]) & 0xFF;
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}
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return neg8;
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}
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/// Returns true if the frame's last byte equals the NEG8 of all preceding bytes.
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bool validateFrame(Uint8List frame) {
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if (frame.isEmpty) return false;
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int neg8 = 0;
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for (int i = 0; i < frame.length - 1; i++) {
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neg8 = (neg8 - frame[i]) & 0xFF;
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}
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return neg8 == frame[frame.length - 1];
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}
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