mirror of
https://github.com/eried/portapack-mayhem.git
synced 2025-01-12 07:49:32 -05:00
ab364ca497
This is the POCSAG code before reformat to put smooth and extract packets in the correct place
453 lines
13 KiB
C++
453 lines
13 KiB
C++
#include "extract_frame_pager.hpp"
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#include <algorithm> // std::max
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#include <cmath>
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#define BAUD_STABLE (104)
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#define MAX_CONSEC_SAME (32)
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#define MAX_WITHOUT_SINGLE (64)
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#define MAX_BAD_TRANS (10)
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#define M_SYNC (0x7cd215d8)
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#define M_NOTSYNC (0x832dea27)
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#define M_IDLE (0x7a89c197)
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// ====================================================================
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//
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// ====================================================================
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inline int bitsDiff(unsigned long left, unsigned long right)
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{
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unsigned long xord = left ^ right;
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int count = 0;
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for (int i = 0; i < 32; i++)
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{
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if ((xord & 0x01) != 0) ++count;
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xord = xord >> 1;
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}
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return(count);
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}
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//////////////////////////////////////////////////////////////////////
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// Construction/Destruction
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//////////////////////////////////////////////////////////////////////
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extract_frame_pager::extract_frame_pager()
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{
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init();
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}
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// ====================================================================
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//
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// ====================================================================
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extract_frame_pager::~extract_frame_pager()
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{
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}
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// ====================================================================
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//
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// ====================================================================
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void extract_frame_pager::init()
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{
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m_averageSymbolLen_1024 = m_maxSymSamples_1024;
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m_lastStableSymbolLen_1024 = m_minSymSamples_1024;
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m_badTransitions = 0;
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m_bitsStart = 0;
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m_bitsEnd = 0;
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m_inverted = false;
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resetVals();
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}
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// ====================================================================
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//
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// ====================================================================
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void extract_frame_pager::resetVals()
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{
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// Set up the xtraction mode
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m_detectionMode = DM_DYNAMIC;
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// Reset the parameters
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// --------------------
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m_goodTransitions = 0;
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m_badTransitions = 0;
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m_averageSymbolLen_1024 = m_maxSymSamples_1024;
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m_shortestGoodTrans_1024 = m_maxSymSamples_1024;
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m_valMid = 0;
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// And reset the counts
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// --------------------
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m_lastTransPos_1024 = 0;
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m_lastBitPos_1024 = 0;
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m_lastSample = 0;
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m_sampleNo = 0;
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m_nextBitPos_1024 = m_maxSymSamples_1024;
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m_nextBitPosInt = (long)m_nextBitPos_1024;
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// Extraction
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m_fifo.numBits = 0;
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m_gotSync = false;
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m_numCode = 0;
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}
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// ====================================================================
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//
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// ====================================================================
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void extract_frame_pager::setParams(long a_samplesPerSec, long a_maxBaud, long a_minBaud, long maxRunOfSameValue)
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{
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m_samplesPerSec = a_samplesPerSec;
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m_minSymSamples_1024 = (uint32_t)(1024.0f * (float)a_samplesPerSec / (float)a_maxBaud);
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m_maxSymSamples_1024 = (uint32_t)(1024.0f*(float)a_samplesPerSec / (float)a_minBaud);
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m_maxRunOfSameValue = maxRunOfSameValue;
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m_shortestGoodTrans_1024 = m_maxSymSamples_1024;
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m_averageSymbolLen_1024 = m_maxSymSamples_1024;
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m_lastStableSymbolLen_1024 = m_minSymSamples_1024;
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m_nextBitPos_1024 = m_averageSymbolLen_1024 / 2;
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m_nextBitPosInt = m_nextBitPos_1024 >> 10;
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init();
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}
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// ====================================================================
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//
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// ====================================================================
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int extract_frame_pager::processDemodulatedSamples(float * sampleBuff, int noOfSamples)
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{
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bool transition = false;
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uint32_t samplePos_1024 = 0;
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uint32_t len_1024 = 0;
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// Loop through the block of data
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// ------------------------------
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for (int pos = 0; pos < noOfSamples; ++pos)
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{
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m_sample = sampleBuff[pos];
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m_valMid += (m_sample - m_valMid) / 1024.0f;
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++m_sampleNo;
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// Detect Transition
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// -----------------
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transition = ! ((m_lastSample < m_valMid) ^ (m_sample >= m_valMid)); // use XOR for speed
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// If this is a transition
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// -----------------------
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if (transition)
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{
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// Calculate samples since last trans
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// ----------------------------------
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int32_t fractional_1024 = (int32_t)(((m_sample - m_valMid)*1024) / (m_sample - m_lastSample));
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if (fractional_1024 < 0) { fractional_1024 = -fractional_1024; }
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samplePos_1024 = (m_sampleNo<<10)-fractional_1024;
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len_1024 = samplePos_1024 - m_lastTransPos_1024;
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m_lastTransPos_1024 = samplePos_1024;
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// If symbol is large enough to be valid
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// -------------------------------------
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if (len_1024 > m_minSymSamples_1024)
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{
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// Check for shortest good transition
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// ----------------------------------
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if ((len_1024 < m_shortestGoodTrans_1024) &&
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(m_goodTransitions < BAUD_STABLE)) // detect change of symbol size
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{
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int32_t fractionOfShortest_1024 = (len_1024<<10) / m_shortestGoodTrans_1024;
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// If currently at half the baud rate
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// ----------------------------------
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if ((fractionOfShortest_1024 > 410) && (fractionOfShortest_1024 < 614)) // 0.4 and 0.6
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{
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m_averageSymbolLen_1024 /= 2;
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m_shortestGoodTrans_1024 = len_1024;
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}
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// If currently at the wrong baud rate
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// -----------------------------------
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else if (fractionOfShortest_1024 < 768) // 0.75
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{
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m_averageSymbolLen_1024 = len_1024;
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m_shortestGoodTrans_1024 = len_1024;
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m_goodTransitions = 0;
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m_lastSingleBitPos_1024 = samplePos_1024 - len_1024;
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}
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}
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// Calc the number of bits since events
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// ------------------------------------
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int32_t halfSymbol_1024 = m_averageSymbolLen_1024 / 2;
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int bitsSinceLastTrans = max((uint32_t)1, (len_1024+halfSymbol_1024) / m_averageSymbolLen_1024 );
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int bitsSinceLastSingle = (((m_sampleNo<<10)-m_lastSingleBitPos_1024) + halfSymbol_1024) / m_averageSymbolLen_1024;
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// Check for single bit
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// --------------------
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if (bitsSinceLastTrans == 1)
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{
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m_lastSingleBitPos_1024 = samplePos_1024;
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}
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// If too long since last transition
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// ---------------------------------
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if (bitsSinceLastTrans > MAX_CONSEC_SAME)
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{
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resetVals();
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}
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// If too long sice last single bit
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// --------------------------------
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else if (bitsSinceLastSingle > MAX_WITHOUT_SINGLE)
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{
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resetVals();
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}
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else
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{
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// If this is a good transition
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// ----------------------------
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int32_t offsetFromExtectedTransition_1024 = len_1024 - (bitsSinceLastTrans*m_averageSymbolLen_1024);
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if (offsetFromExtectedTransition_1024 < 0) { offsetFromExtectedTransition_1024 = -offsetFromExtectedTransition_1024; }
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if (offsetFromExtectedTransition_1024 < (m_averageSymbolLen_1024 / 4)) // Has to be within 1/4 of symbol to be good
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{
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++m_goodTransitions;
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uint32_t bitsCount = min((uint32_t)BAUD_STABLE, m_goodTransitions);
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uint32_t propFromPrevious = m_averageSymbolLen_1024*bitsCount;
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uint32_t propFromCurrent = (len_1024 / bitsSinceLastTrans);
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m_averageSymbolLen_1024 = (propFromPrevious + propFromCurrent) / (bitsCount + 1);
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m_badTransitions = 0;
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//if ( len < m_shortestGoodTrans ){m_shortestGoodTrans = len;}
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// Store the old symbol size
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if (m_goodTransitions >= BAUD_STABLE)
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{
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m_lastStableSymbolLen_1024 = m_averageSymbolLen_1024;
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}
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}
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// Not a good transition
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// ---------------------
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else
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{
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// m_goodTransitions = 0;
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}
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}
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// Set the point of the last bit if not yet stable
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// -----------------------------------------------
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if ((m_goodTransitions < BAUD_STABLE) || (m_badTransitions > 0))
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{
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m_lastBitPos_1024 = samplePos_1024 - (m_averageSymbolLen_1024 / 2);
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}
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// Calculate the exact positiom of the next bit
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// --------------------------------------------
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int32_t thisPlusHalfsymbol_1024 = samplePos_1024 + (m_averageSymbolLen_1024/2);
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int32_t lastPlusSymbol = m_lastBitPos_1024 + m_averageSymbolLen_1024;
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m_nextBitPos_1024 = lastPlusSymbol + ((thisPlusHalfsymbol_1024 - lastPlusSymbol) / 16);
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// Check for bad pos error
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// -----------------------
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if (m_nextBitPos_1024 < samplePos_1024) m_nextBitPos_1024 += m_averageSymbolLen_1024;
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// Calculate integer sample after next bit
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// ---------------------------------------
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m_nextBitPosInt = (m_nextBitPos_1024>>10) + 1;
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} // symbol is large enough to be valid
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else
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{
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// Bad transition, so reset the counts
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// -----------------------------------
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++m_badTransitions;
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if (m_badTransitions > MAX_BAD_TRANS)
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{
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resetVals();
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}
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}
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} // end of if transition
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else
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{
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//TRACE("Len too small %f",len);
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}
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// Reached the point of the next bit
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// ---------------------------------
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if (m_sampleNo >= m_nextBitPosInt)
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{
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// Everything is good so extract a bit
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// -----------------------------------
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if (m_goodTransitions > 20)
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{
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// Store value at the center of bit
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// --------------------------------
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storeBit();
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}
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// Check for long 1 or zero
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// ------------------------
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int bitsSinceLastTrans = ((m_sampleNo<<10) - m_lastTransPos_1024) / m_averageSymbolLen_1024;
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if (bitsSinceLastTrans > m_maxRunOfSameValue)
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{
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resetVals();
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}
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// Store the point of the last bit
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// -------------------------------
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m_lastBitPos_1024 = m_nextBitPos_1024;
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// Calculate the exact point of the next bit
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// -----------------------------------------
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m_nextBitPos_1024 += m_averageSymbolLen_1024;
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// Look for the bit after the next bit pos
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// ---------------------------------------
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m_nextBitPosInt = (m_nextBitPos_1024>>10) + 1;
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} // Reached the point of the next bit
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m_lastSample = m_sample;
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} // Loop through the block of data
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return getNoOfBits();
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}
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// ====================================================================
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//
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// ====================================================================
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void extract_frame_pager::storeBit()
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{
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if (++m_bitsStart >= BIT_BUF_SIZE) { m_bitsStart = 0; }
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// Calculate the bit value
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float sample = (m_sample + m_lastSample) / 2;
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//int32_t sample_1024 = m_sample_1024;
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bool bit = sample > m_valMid;
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// If buffer not full
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if (m_bitsStart != m_bitsEnd)
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{
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// Decide on output val
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if (bit)
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{
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m_bits[m_bitsStart] = 0;
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}
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else
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{
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m_bits[m_bitsStart] = 1;
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}
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}
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// Throw away bits if the buffer is full
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else
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{
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if (--m_bitsStart <= -1)
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{
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m_bitsStart = BIT_BUF_SIZE - 1;
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}
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}
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}
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// ====================================================================
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//
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// ====================================================================
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int extract_frame_pager::extractFrames()
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{
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int msgCnt = 0;
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// While there is unread data in the bits buffer
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//----------------------------------------------
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while (getNoOfBits() > 0)
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{
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m_fifo.codeword = (m_fifo.codeword << 1) + getBit();
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m_fifo.numBits++;
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// If number of bits in fifo equals 32
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//------------------------------------
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if (m_fifo.numBits >= 32)
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{
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// Not got sync
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// ------------
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if (!m_gotSync)
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{
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if (bitsDiff(m_fifo.codeword, M_SYNC) <= 2)
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{
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m_inverted = false;
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m_gotSync = true;
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m_numCode = -1;
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m_fifo.numBits = 0;
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//TRACE("SYNC %x %d\n", m_fifo.codeword, m_numCode);
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}
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else if (bitsDiff(m_fifo.codeword, M_NOTSYNC) <= 2)
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{
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m_inverted = true;
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m_gotSync = true;
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m_numCode = -1;
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m_fifo.numBits = 0;
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//TRACE("ISYNC %x %d\n", m_fifo.codeword, m_numCode);
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}
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else
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{
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// Cause it to load one more bit
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m_fifo.numBits = 31;
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}
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} // Not got sync
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else
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{
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// Increment the word count
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// ------------------------
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++m_numCode; // It got set to -1 when a sync was found, now count the 16 words
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uint32_t val = m_inverted ? ~m_fifo.codeword : m_fifo.codeword;
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OnDataWord(val, m_numCode);
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//TRACE("WORD %x %d\n", m_fifo.codeword, m_numCode);
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// If at the end of a 16 word block
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// --------------------------------
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if (m_numCode >= 15)
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{
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msgCnt += OnDataFrame(m_numCode+1, (m_samplesPerSec<<10) / m_lastStableSymbolLen_1024);
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m_gotSync = false;
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m_numCode = -1;
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}
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m_fifo.numBits = 0;
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}
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} // If number of bits in fifo equals 32
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} // While there is unread data in the bits buffer
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return msgCnt;
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} // extractFrames
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// ====================================================================
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//
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// ====================================================================
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//
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// ====================================================================
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short extract_frame_pager::getBit()
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{
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if (m_bitsEnd != m_bitsStart)
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{
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if (++m_bitsEnd >= BIT_BUF_SIZE)
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{
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m_bitsEnd = 0;
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}
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return m_bits[m_bitsEnd];
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}
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else
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{
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return -1;
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}
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}
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// ====================================================================
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//
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// ====================================================================
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int extract_frame_pager::getNoOfBits()
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{
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int bits = m_bitsEnd - m_bitsStart;
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if (bits < 0) { bits += BIT_BUF_SIZE; }
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return bits;
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}
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// ====================================================================
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//
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// ====================================================================
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uint32_t extract_frame_pager::getRate()
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{
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return ((m_samplesPerSec<<10)+512) / m_lastStableSymbolLen_1024;
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}
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