jens
8b6d6313e5
git-svn-id: http://moon:8086/svn/software/trunk/libsrc/cpp@1077 b431acfa-c32f-4a4a-93f1-934dc6c82436
107 lines
2.2 KiB
C++
107 lines
2.2 KiB
C++
// --------------------------------------------------------------
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#include <string.h>
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#include <math.h>
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#include <stdint.h>
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#include "DeSymbolizer.hpp"
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DeSymbolizer::DeSymbolizer()
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: Processor::Block(1, 1)
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, m_dataBitCount(0)
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, m_lastSymbol(0)
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, m_symbolMask(0)
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, m_nBitsPerSym(0)
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{
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setNumBitsPerSymbol(8);
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}
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void DeSymbolizer::setNumBitsPerSymbol(uint32_t nBitsPerSym)
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{
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m_nBitsPerSym = nBitsPerSym;
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m_symbolMask = 0;
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for(uint32_t k=0; k < nBitsPerSym; k++)
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{
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m_symbolMask <<= 1;
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m_symbolMask |= 1;
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}
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m_dataBitCount = 0;
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m_lastSymbol = 0;
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}
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void DeSymbolizer::process(uint32_t src)
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{
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uint32_t i, j;
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static uint8_t dst;
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static uint16_t preamble;
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uint16_t preamble_soll;
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uint32_t symSync;
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src = differentialDecode(src);
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symSync = src;
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const uint8_t preamble_bytes[2] = {(uint8_t)FRAME_PREAMBLE_IV, (uint8_t)(~FRAME_PREAMBLE_IV)};
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preamble_soll = ((uint16_t)preamble_bytes[0] << 8) | ((uint16_t)preamble_bytes[1] & 0xFF);
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j = 0;
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for (i=0; i < m_nBitsPerSym; i++)
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{
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preamble <<= 1;
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preamble |= (uint32_t)((symSync >> (m_nBitsPerSym-1) & 1) != 0);
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symSync <<= 1;
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if (preamble == preamble_soll)
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{
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// We have bit sync
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m_dataBitCount = 0;
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j = i + 1;
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src = symSync;
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preamble = 0;
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m_buf_out->write(preamble_bytes, sizeof(preamble_bytes));
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}
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}
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// Transmission order MSB first
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for (i=j; i < m_nBitsPerSym; i++)
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{
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dst <<= 1;
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dst |= (uint32_t)((src >> (m_nBitsPerSym-1) & 1) != 0);
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src <<= 1;
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m_dataBitCount++;
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if (m_dataBitCount == SIZEOF_DATA_BITS)
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{
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m_buf_out->write(&dst, 1);
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m_dataBitCount = 0;
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dst = 0;
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}
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}
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}
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void DeSymbolizer::prepare()
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{
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// Get buffers
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m_buf_in = buffer_in<symbol_t>();
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m_buf_out = buffer_out<uint8_t>();
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}
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void DeSymbolizer::process()
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{
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// Process input
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while(m_buf_in->len())
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{
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symbol_t sym;
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m_buf_in->read(&sym, 1);
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process(sym);
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}
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}
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uint32_t DeSymbolizer::differentialDecode(uint32_t symbol)
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{
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uint32_t res;
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// Differential decode
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res = (uint32_t)(m_symbolMask & (symbol - m_lastSymbol));
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m_lastSymbol = symbol;
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return res;
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}
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// --------------------------------------------------------------
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