add SNRdB calculation for STV0288 based frontends

diff --git a/lib/dvb/frontend.cpp b/lib/dvb/frontend.cpp
index 255efd08c8edb3b6f82fa9878ef60f263d601129..79c9ad0bccbc9556b3c4ab0ad53aca06292a4979 100644 (file)
--- a/lib/dvb/frontend.cpp
+++ b/lib/dvb/frontend.cpp
@@ -656,6 +656,8 @@ void eDVBFrontend::timeout()
        }
 }
 
+#define INRANGE(X,Y,Z) (((X<=Y) && (Y<=Z))||((Z<=Y) && (Y<=X)) ? 1 : 0)
+
 int eDVBFrontend::readFrontendData(int type)
 {
        switch(type)
@@ -712,6 +714,49 @@ int eDVBFrontend::readFrontendData(int type)
                        
                                return (int)(snr_in_db * 100.0);
                        }
+                       else if (strstr(m_description, "Alps BSBE1 C01A") ||
+                               !strcmp(m_description, "Alps -S(STV0288)"))
+                       {
+                               if (snr == 0)
+                                       return 0;
+                               else if (snr == 0xFFFF) // i think this should not happen
+                                       return 100*100;
+                               else
+                               {
+                                       enum { REALVAL, REGVAL };
+                                       const long CN_lookup[31][2] = {
+                                               {20,8900}, {25,8680}, {30,8420}, {35,8217}, {40,7897},
+                                               {50,7333}, {60,6747}, {70,6162}, {80,5580}, {90,5029},
+                                               {100,4529}, {110,4080}, {120,3685}, {130,3316}, {140,2982},
+                                               {150,2688}, {160,2418}, {170,2188}, {180,1982}, {190,1802},
+                                               {200,1663}, {210,1520}, {220,1400}, {230,1295}, {240,1201},
+                                               {250,1123}, {260,1058}, {270,1004}, {280,957}, {290,920},
+                                               {300,890}
+                                       };
+                                       long regval = 0xFFFF - ((snr / 3) + 0xA100), // revert some dvb api calulations to get the real register value
+                                               Imin=0,
+                                               Imax=30,
+                                               i;
+                                       if(INRANGE(CN_lookup[Imin][REGVAL],regval,CN_lookup[Imax][REGVAL]))
+                                       {
+                                               long val;
+                                               while((Imax-Imin)>1)
+                                               {
+                                                       i=(Imax+Imin)/2;
+                                                       if(INRANGE(CN_lookup[Imin][REGVAL],regval,CN_lookup[i][REGVAL]))
+                                                               Imax = i;
+                                                       else
+                                                               Imin = i;
+                                               }
+                                               return (((regval - CN_lookup[Imin][REGVAL])
+                                                               * (CN_lookup[Imax][REALVAL] - CN_lookup[Imin][REALVAL])
+                                                               / (CN_lookup[Imax][REGVAL] - CN_lookup[Imin][REGVAL]))
+                                                               + CN_lookup[Imin][REALVAL]) * 10;
+                                       }
+                                       return 100;
+                               }
+                               return 0;
+                       }
                        else if (!strcmp(m_description, "Alps BSBE1 702A") ||  // some frontends with STV0299
                                !strcmp(m_description, "Alps -S") ||
                                !strcmp(m_description, "Philips -S") ||