satdump/src-core/common/codings/differential/qpsk_diff.cpp

#include "qpsk_diff.h"

namespace diff
{
    void QPSKDiff::work(uint8_t *in, int len, uint8_t *out)
    {
        oo = 0;

        // Process all given samples
        for (int ii = 0; ii < len; ii++)
        {
            uint8_t &sample = in[ii];

            // Push new sample into buffer
            buffer[0] = buffer[1];
            buffer[1] = sample;

            // We need at least 2
            if (inBuf < 2)
            {
                inBuf++;
                continue;
            }

            // Perform differential decoding
            Xin_1 = buffer[0] & 0x02;
            Yin_1 = buffer[0] & 0x01;
            Xin = buffer[1] & 0x02;
            Yin = buffer[1] & 0x01;
            if (((Xin >> 1) ^ Yin) == 1)
            {
                Xout = (Yin_1 ^ Yin);
                Yout = (Xin_1 ^ Xin);
                ou = (Xout << 1) + (Yout >> 1);
            }
            else
            {
                Xout = (Xin_1 ^ Xin);
                Yout = (Yin_1 ^ Yin);
                ou = (Xout + Yout);
            }

            // Output is inverted on CFOSAT
            if (swap)
            {
                out[oo * 2 + 0] = ou & 1;
                out[oo * 2 + 1] = ou >> 1;
            }
            else
            {
                out[oo * 2 + 0] = ou >> 1;
                out[oo * 2 + 1] = ou & 1;
            }
            oo++;
        }
    }
} // namespace fengyun