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Update passall rules in HDLC decoder to align more closely with AX.25 specs.

kf7r_9600_experimental
Rob Riggs 2020-02-22 21:35:32 -06:00
rodzic 1a18b3dd1b
commit f72a9a3ff6
1 zmienionych plików z 20 dodań i 5 usunięć
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25
TNC/HdlcDecoder.cpp
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@ -63,24 +63,31 @@ uint8_t NewDecoder::process(bool input, bool pll_lock)
if (flag) {
switch (buffer) {
case 0x7E:
if (packet->size() > 0) {
if (packet->size() > 2) {
// We have started decoding a packet.
packet->parse_fcs();
report_bits = bits;
if (packet->ok()) {
// CRC is OK, assume a good packet, even if there are
// extraneous bits decoded.
if (packet->size() < 15) {
// 120 (136) bits per AX.25 section 3.9.
// Note we discard the flags.
result_code = STATUS_FRAME_ERROR;
} else if (packet->ok()) {
// Not compliant with AX.25 section 3.9.
// We ignore byte alignment when FCS is OK.
result_code = STATUS_OK;
} else if (bits == 8) {
// Otherwise, if there is a CRC error but we are on
// an even byte boundary, flag a CRC error. This is
// used by the "pass all" rule.
// Must be byte-aligned per AX.25 section 3.9.
result_code = STATUS_CRC_ERROR;
} else {
// Extraneous bits mean we have a framing error.
// We should not pass this frame up the stack.
result_code = STATUS_FRAME_ERROR;
}
} else {
packet->clear();
}
state = State::SYNC;
flag = 0;
@ -129,12 +136,20 @@ uint8_t NewDecoder::process(bool input, bool pll_lock)
if (packet->size() > 2)
{
packet->parse_fcs();
if (packet->ok())
if (packet->size() < 15) {
// 120 (136) bits per AX.25 section 3.9.
// Note we discard the flags.
result_code = STATUS_NO_CARRIER;
}
else if (packet->ok())
{
// Not compliant with AX.25 section 3.9.
// We ignore byte alignment when FCS is OK.
result_code = STATUS_OK;
}
else if (bits == 8)
{
// Must be byte-aligned per AX.25 section 3.9.
result_code = STATUS_CRC_ERROR;
}
else