optional hack for dm8000: convert FE_READ_SNR into dB (will soon be moved into driver)

diff --git a/lib/dvb/frontend.cpp b/lib/dvb/frontend.cpp
index 3ae9473..f9ca6c7 100644 (file)
--- a/lib/dvb/frontend.cpp
+++ b/lib/dvb/frontend.cpp
@@ -623,6 +623,39 @@ int eDVBFrontend::readFrontendData(int type)
                        uint16_t snr=0;
                        if (ioctl(m_fd, FE_READ_SNR, &snr) < 0 && errno != ERANGE)
                                eDebug("FE_READ_SNR failed (%m)");
+
+#if defined(DM8000)
+                       unsigned int SDS_SNRE = snr << 16;
+                       
+                       static float SNR_COEFF[6] = {
+                               100.0 / 4194304.0,
+                               -7136.0 / 4194304.0,
+                               197418.0 / 4194304.0,
+                               -2602183.0 / 4194304.0,
+                               20377212.0 / 4194304.0,
+                               -37791203.0 / 4194304.0,
+                       };
+                       
+                       float fval1, fval2, snr_in_db;
+                       int i;
+                       fval1 = 12.44714 - (2.0 * log10(SDS_SNRE / 256.0));
+                       fval2 = pow(10.0, fval1)-1;
+                       fval1 = 10.0 * log10(fval2);
+                       
+                       if (fval1 < 10.0)
+                       {
+                               fval2 = SNR_COEFF[0];
+                               for (i=0; i<6; ++i)
+                               {
+                                       fval2 *= fval1;
+                                       fval2 += SNR_COEFF[i];
+                               }
+                               fval1 = fval2;
+                       }
+                       snr_in_db = fval1;
+                       
+                       return (int)(snr_in_db * 100.0);
+#endif
                        return snr;
                }
                case signalQuality: