gsm-receiver: EFR support [2/3] Add unmapping support to OpenBTS TCH …

…decoder

Signed-off-by: Sylvain Munaut <[email protected]>

gsm-receiver/src/lib/decoder/openbtsstuff/GSML1FEC.cpp

@@ -30,6 +30,8 @@
 //#include "GSMConfig.h"
 #include "GSMTDMA.h"
 #include "GSM610Tables.h"
+#include "GSM660Tables.h"
+#include "GSM690Tables.h"
 #include "Assert.h"
 
 
@@ -78,7 +80,7 @@ using namespace GSM;
 TCHFACCHL1Decoder::TCHFACCHL1Decoder(const TDMAMapping& wMapping)
     : mTCHU(189), mTCHD(260), mC(456),
     mClass1_c(mC.head(378)), mClass1A_d(mTCHD.head(50)), mClass2_c(mC.segment(378, 78)),
-    mTCHParity(0x0b, 3, 50), mMapping(wMapping)
+    mTCHParity(0x0b, 3, 50), mMapping(wMapping), mMode(MODE_SPEECH_FR)
 {
   for (int i = 0; i < 8; i++) {
     mI[i] = SoftVector(114);
@@ -186,10 +188,6 @@ bool TCHFACCHL1Decoder::decodeTCH(bool stolen)
   // If the frame wasn't stolen, we'll update this with parity later.
   bool good = !stolen;
 
-  // Good or bad, we will be sending *something* to the speech channel.
-  // Allocate it in this scope.
-  unsigned char * newFrame = new unsigned char[33];
-
   if (!stolen) {
 
     // 3.1.2.2
@@ -226,29 +224,47 @@ bool TCHFACCHL1Decoder::decodeTCH(bool stolen)
              << " calcParity=" << calcParity << " tail=" << tail);
     good = (sentParity == calcParity) && (tail == 0);
     if (good) {
-      // Undo Um's importance-sorted bit ordering.
-      // See GSM 05.03 3.1 and Tablee 2.
-      BitVector payload = mVFrame.payload();
-      mTCHD.unmap(g610BitOrder, 260, payload);
-      mVFrame.pack(newFrame);
-      // Save a copy for bad frame processing.
-      memcpy(mPrevGoodFrame, newFrame, 33);
-      return true;
-    }
-  }
+      if (mMode == MODE_SPEECH_FR) {
+        // Undo Um's importance-sorted bit ordering.
+        // See GSM 05.03 3.1 and Tablee 2.
+        BitVector payload = mVFrame.payload();
+        mTCHD.unmap(g610BitOrder, 260, payload);
+        mVFrame.pack(mPrevGoodFrame);
+        mPrevGoodFrameLength = 33;
+      } else if (mMode == MODE_SPEECH_EFR) {
+        BitVector payload = mVFrameAMR.payload();
+        BitVector TCHW(260), EFRBits(244);
 
-  if (!good) {
-    // TODO -- Bad frame processing, GSM 06.11.
-    // For now, just repeat the last good frame.
-    // TODO -- Need to apply attenuation and randomization of grid positions.
-    memcpy(newFrame, mPrevGoodFrame, 33);
-    //d_gsm_file.write((char *)newFrame, 33);
-  }
+        // Undo Um's EFR bit ordering.
+        mTCHD.unmap(g660BitOrder, 260, TCHW);
+
+        // Remove repeating bits and CRC to get raw EFR frame (244 bits)
+        for (unsigned k=0; k<71; k++)
+          EFRBits[k] = TCHW[k] & 1;
+
+        for (unsigned k=73; k<123; k++)
+          EFRBits[k-2] = TCHW[k] & 1;
 
-
-  // Good or bad, we must feed the speech channel.
-// mSpeechQ.write(newFrame);
+        for (unsigned k=125; k<178; k++)
+          EFRBits[k-4] = TCHW[k] & 1;
 
+        for (unsigned k=180; k<230; k++)
+          EFRBits[k-6] = TCHW[k] & 1;
+
+        for (unsigned k=232; k<252; k++)
+          EFRBits[k-8] = TCHW[k] & 1;
+
+        // Map bits as AMR 12.2k
+        EFRBits.map(g690_12_2_BitOrder, 244, payload);
+
+        // Put the whole frame (hdr + payload)
+        mVFrameAMR.pack(mPrevGoodFrame);
+        mPrevGoodFrameLength = 32;
+      }
+
+      return true;
+    }
+  }
 
   return false;
 }

gsm-receiver/src/lib/decoder/openbtsstuff/GSML1FEC.h

@@ -58,6 +58,10 @@ namespace GSM
   */
 
 
+  enum TCHMode {
+    MODE_SPEECH_FR,
+    MODE_SPEECH_EFR,
+  };
 
 
   /** L1 decoder used for full rate TCH and FACCH -- mostly from GSM 05.03 3.1 and 4.2 */
@@ -75,8 +79,10 @@ namespace GSM
       SoftVector mClass2_c;    ///< the class 2 part of c[]
       ViterbiR2O4 mVCoder;
 
-      VocoderFrame mVFrame;    ///< unpacking buffer for vocoder frame
+      VocoderFrame mVFrame;    ///< buffer for FR vocoder frame
+      VocoderAMRFrame mVFrameAMR; ///< buffer for EFR vocoder frame packed in AMR container
       unsigned char mPrevGoodFrame[33]; ///< previous good frame.
+      unsigned int  mPrevGoodFrameLength;
 
       Parity mTCHParity;
       const TDMAMapping& mMapping; ///< multiplexing description
@@ -85,6 +91,7 @@ namespace GSM
 
       static const unsigned mMaxQSize = 3;
 
+      enum TCHMode mMode;
 
     public:
 
@@ -94,6 +101,14 @@ namespace GSM
         return FACCHType;
       }
 
+      enum TCHMode mode() const {
+        return mMode;
+      }
+
+      void setMode(enum TCHMode mode) {
+        mMode = mode;
+      }
+
 
       /** TCH/FACCH has a special-case writeLowSide. */
       void writeLowSide(const RxBurst& inBurst);
@@ -118,6 +133,9 @@ namespace GSM
       unsigned char * get_voice_frame(){
         return mPrevGoodFrame;
       }
+      unsigned int get_voice_frame_length(){
+        return mPrevGoodFrameLength;
+      }
       /**
        Receive a traffic frame.
        Non-blocking.  Returns NULL if queue is dry.

gsm-receiver/src/lib/decoder/openbtsstuff/VocoderFrame.h

@@ -22,4 +22,22 @@ class VocoderFrame : public BitVector {
 
 };
 
+class VocoderAMRFrame : public BitVector {
+
+        public:
+
+        VocoderAMRFrame()
+                :BitVector(244+8)
+        { fillField(0,0x3c,8); /* AMR-NB 12.2 */ }
+
+        /** Construct by unpacking a char[32]. */
+        VocoderAMRFrame(const unsigned char *src)
+                :BitVector(244+8)
+        { unpack(src); }
+
+        BitVector payload() { return tail(8); }
+        const BitVector payload() const { return tail(8); }
+
+};
+
 #endif