add ryfi decoder module

2026-04-20 15:22:42 +00:00 · 2024-07-24 16:31:29 +02:00
parent 949fde022d
commit 554ba2f596
17 changed files with 1568 additions and 0 deletions
--- a/decoder_modules/ryfi_decoder/src/ryfi/framing.cpp
+++ b/decoder_modules/ryfi_decoder/src/ryfi/framing.cpp
@@ -0,0 +1,137 @@
+#include "framing.h"
+
+namespace ryfi {
+    dsp::complex_t QPSK_SYMBOLS[4] = {
+        { -0.070710678118f, -0.070710678118f },
+        { -0.070710678118f,  0.070710678118f },
+        {  0.070710678118f, -0.070710678118f },
+        {  0.070710678118f,  0.070710678118f },
+    };
+
+    Framer::Framer(dsp::stream<uint8_t>* in) {
+        // Generate the sync symbols
+        int k = 0;
+        for (int i = 62; i >= 0; i -= 2) {
+            syncSyms[k++] = QPSK_SYMBOLS[(SYNC_WORD >> i) & 0b11];
+        }
+        
+
+        // Initialize base class
+        base_type::init(in);
+    }
+
+    int Framer::encode(const uint8_t* in, dsp::complex_t* out, int count) {
+        // Copy sync symbols
+        memcpy(out, syncSyms, SYNC_SYMS*sizeof(dsp::complex_t));
+
+        // Modulate the rest of the bits
+        dsp::complex_t* dataOut = &out[SYNC_SYMS];
+        int dataSyms = count / 2;
+        for (int i = 0; i < dataSyms; i++) {
+            uint8_t bits = (in[i >> 2] >> (6 - 2*(i & 0b11))) & 0b11;
+            dataOut[i] = QPSK_SYMBOLS[bits];
+        }
+
+        // Compute and return the total number of symbols
+        return SYNC_SYMS + dataSyms;
+    }
+
+    int Framer::run() {
+        int count = base_type::_in->read();
+        if (count < 0) { return -1; }
+
+        count = encode(base_type::_in->readBuf, base_type::out.writeBuf, count);
+
+        base_type::_in->flush();
+        if (!out.swap(count)) { return -1; }
+        return count;
+    }
+
+    Deframer::Deframer(dsp::stream<dsp::complex_t> *in) {
+        // Compute sync word rotations
+        //   0: 00 01 11 10
+        //  90: 10 00 01 11
+        // 180: 11 10 00 01
+        // 270: 01 11 10 00
+
+        // For 0 and 180 it's the sync and its complement
+        syncRots[ROT_0_DEG] = SYNC_WORD;
+        syncRots[ROT_180_DEG] = ~SYNC_WORD;
+        
+        // For 90 and 270 its the quadrature and its complement
+        uint64_t quad;
+        for (int i = 62; i >= 0; i -= 2) {
+            // Get the symbol
+            uint8_t sym = (SYNC_WORD >> i) & 0b11;
+
+            // Rotate it 90 degrees
+            uint8_t rsym;
+            switch (sym) {
+                case 0b00:  rsym = 0b10; break;
+                case 0b01:  rsym = 0b00; break;
+                case 0b11:  rsym = 0b01; break;
+                case 0b10:  rsym = 0b11; break;
+            }
+
+            // Push it into the quadrature
+            quad = (quad << 2) | rsym;
+        }
+        syncRots[ROT_90_DEG] = quad;
+        syncRots[ROT_270_DEG] = ~quad;
+
+        base_type::init(in);
+    }
+
+    int Deframer::run() {
+        int count = base_type::_in->read();
+        if (count < 0) { return -1; }
+
+        dsp::complex_t* in = base_type::_in->readBuf;
+
+        for (int i = 0; i < count; i++) {
+            if (recv) {
+                // Copy the symbol to the output and rotate it approprieate
+                base_type::out.writeBuf[outCount++] = in[i] * symRot;
+
+                // Check if we're done receiving the frame, send it out
+                if (!(--recv)) {
+                    if (!base_type::out.swap(outCount)) {
+                        base_type::_in->flush();
+                        return -1;
+                    }
+                }
+            }
+            else {
+                // Get the raw symbol
+                dsp::complex_t fsym = in[i];
+
+                // Decode the symbol
+                uint8_t sym = ((fsym.re > 0) ? 0b10 : 0b00) | ((fsym.im > 0) ? 0b01 : 0b00);
+
+                // Push it to the shift register
+                shift = (shift << 2) | sym;
+
+                // Find the rotation starting with the last known one
+                for (int i = 0; i < 4; i++) {
+                    // Get the test rotation
+                    int testRot = (knownRot+i) & 0b11;
+
+                    // Check if the hamming distance is close enough
+                    int dist;
+                    if (distance(shift, syncRots[testRot]) < 6) {
+                        // Save the new rotation
+                        knownRot = testRot;
+
+                        // Start reading in symbols for the frame
+                        symRot = symRots[knownRot];
+                        recv = 8168; // TODO: Don't hardcode!
+                        outCount = 0;
+                    }
+                }
+            }
+        }
+
+        base_type::_in->flush();
+        return count;
+    }
+}