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improve pocsag alpha decoding

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AlexandreRouma 2024-02-05 16:46:08 +01:00
parent bddfe5396f
commit f66f2c25e1
3 changed files with 23 additions and 52 deletions
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2
CMakeLists.txt
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@ -43,7 +43,7 @@ option(OPT_BUILD_FALCON9_DECODER "Build the falcon9 live decoder (Dependencies:
option(OPT_BUILD_KG_SSTV_DECODER "Build the KG SSTV (KG-STV) decoder module (no dependencies required)" OFF)
option(OPT_BUILD_M17_DECODER "Build the M17 decoder module (Dependencies: codec2)" OFF)
option(OPT_BUILD_METEOR_DEMODULATOR "Build the meteor demodulator module (no dependencies required)" ON)
option(OPT_BUILD_PAGER_DECODER "Build the pager decoder module (no dependencies required)" OFF)
option(OPT_BUILD_PAGER_DECODER "Build the pager decoder module (no dependencies required)" ON)
option(OPT_BUILD_RADIO "Main audio modulation decoder (AM, FM, SSB, etc...)" ON)
option(OPT_BUILD_WEATHER_SAT_DECODER "Build the HRPT decoder module (no dependencies required)" OFF)

69
decoder_modules/pager_decoder/src/pocsag/pocsag.cpp
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@ -84,27 +84,13 @@ namespace pocsag {
void Decoder::flushMessage() {
if (!msg.empty()) {
// Unpack bits
std::string outStr = "";
for (int i = 0; (i+7) <= msg.size(); i += 7) {
uint8_t b0 = msg[i];
uint8_t b1 = msg[i+1];
uint8_t b2 = msg[i+2];
uint8_t b3 = msg[i+3];
uint8_t b4 = msg[i+4];
uint8_t b5 = msg[i+5];
uint8_t b6 = msg[i+6];
outStr += (char)((b6<<6) | (b5<<5) | (b4<<4) | (b3<<3) | (b2<<2) | (b1<<1) | b0);
}
onMessage(addr, msgType, outStr);
// // Send out message
// onMessage(addr, msgType, msg);
// Send out message
onMessage(addr, msgType, msg);
// Reset state
msg.clear();
leftInLast = 0;
currChar = 0;
currOffset = 0;
}
}
@ -160,42 +146,27 @@ namespace pocsag {
// Decode data depending on message type
if (msgType == MESSAGE_TYPE_NUMERIC) {
// Numeric messages pack 5 characters per message codeword
//msg += NUMERIC_CHARSET[(data >> 16) & 0b1111];
//msg += NUMERIC_CHARSET[(data >> 12) & 0b1111];
//msg += NUMERIC_CHARSET[(data >> 8) & 0b1111];
//msg += NUMERIC_CHARSET[(data >> 4) & 0b1111];
//msg += NUMERIC_CHARSET[data & 0b1111];
msg += NUMERIC_CHARSET[(data >> 16) & 0b1111];
msg += NUMERIC_CHARSET[(data >> 12) & 0b1111];
msg += NUMERIC_CHARSET[(data >> 8) & 0b1111];
msg += NUMERIC_CHARSET[(data >> 4) & 0b1111];
msg += NUMERIC_CHARSET[data & 0b1111];
}
else if (msgType == MESSAGE_TYPE_ALPHANUMERIC) {
// // Alpha messages pack 7bit characters in the entire codeword stream
// int lasti;
// for (int i = -leftInLast; i <= POCSAG_DATA_BITS_PER_CW-7; i += 7) {
// // Read 7 bits
// char c = 0;
// if (i < 0) {
// c = (lastMsgData & ((1 << (-i)) - 1)) << (7+i);
// }
// c |= (data >> (13 - i)) & 0b1111111;
// // Save character
// bitswapChar(c, c);
// msg += c;
// // Update last successful unpack
// lasti = i;
// }
// // Save how much is still left to read
// leftInLast = 20 - (lasti + 7);
// Pack the bits backwards
// Unpack ascii bits 7 at a time (TODO: could be more efficient)
for (int i = 19; i >= 0; i--) {
msg += (char)((data >> i) & 1);
// Append bit to char
currChar |= ((data >> i) & 1) << (currOffset++);
// When the char is full, append to message
if (currOffset >= 7) {
// TODO: maybe replace with std::isprint
if (currChar) { msg += currChar; }
currChar = 0;
currOffset = 0;
}
}
}
// Save last data
lastMsgData = data;
}
}
}

4
decoder_modules/pager_decoder/src/pocsag/pocsag.h
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@ -45,7 +45,7 @@ namespace pocsag {
MessageType msgType;
std::string msg;
uint32_t lastMsgData;
bool leftInLast = 0;
char currChar = 0;
int currOffset = 0;
};
}