diff options
| -rw-r--r-- | Transceiver52M/sigProcLib.cpp | 44 |
1 files changed, 8 insertions, 36 deletions
diff --git a/Transceiver52M/sigProcLib.cpp b/Transceiver52M/sigProcLib.cpp index a72ec43..c776501 100644 --- a/Transceiver52M/sigProcLib.cpp +++ b/Transceiver52M/sigProcLib.cpp @@ -46,14 +46,10 @@ using namespace GSM; #define CLIP_THRESH 30000.0f /** Lookup tables for trigonometric approximation */ -static float cosTable[TABLESIZE+1]; // add 1 element for wrap around -static float sinTable[TABLESIZE+1]; -static float sincTable[TABLESIZE+1]; +static float sincTable[TABLESIZE+1]; // add 1 element for wrap around /** Constants */ static const float M_PI_F = (float)M_PI; -static const float M_2PI_F = (float)(2.0*M_PI); -static const float M_1_2PI_F = 1/M_2PI_F; /* Precomputed rotation vectors */ static signalVector *GMSKRotation4 = NULL; @@ -182,29 +178,6 @@ static float vectorNorm2(const signalVector &x) return Energy; } -/** compute e^(-jx) via lookup table. */ -static complex expjLookup(float x) -{ - float arg = x*M_1_2PI_F; - while (arg > 1.0F) arg -= 1.0F; - while (arg < 0.0F) arg += 1.0F; - - const float argT = arg*((float)TABLESIZE); - const int argI = (int)argT; - const float delta = argT-argI; - const float iDelta = 1.0F-delta; - return complex(iDelta*cosTable[argI] + delta*cosTable[argI+1], - iDelta*sinTable[argI] + delta*sinTable[argI+1]); -} - -/** Library setup functions */ -static void initTrigTables() { - for (int i = 0; i < TABLESIZE+1; i++) { - cosTable[i] = cos(2.0*M_PI*i/TABLESIZE); - sinTable[i] = sin(2.0*M_PI*i/TABLESIZE); - } -} - /* * Initialize 4 sps and 1 sps rotation tables */ @@ -216,11 +189,11 @@ static void initGMSKRotationTables() GMSKReverseRotation4 = new signalVector(len4); signalVector::iterator rotPtr = GMSKRotation4->begin(); signalVector::iterator revPtr = GMSKReverseRotation4->begin(); - float phase = 0.0; + auto phase = 0.0; while (rotPtr != GMSKRotation4->end()) { - *rotPtr++ = expjLookup(phase); - *revPtr++ = expjLookup(-phase); - phase += M_PI_F / 2.0F / 4.0; + *rotPtr++ = complex(cos(phase), sin(phase)); + *revPtr++ = complex(cos(-phase), sin(-phase)); + phase += M_PI / 2.0 / 4.0; } GMSKRotation1 = new signalVector(len1); @@ -229,9 +202,9 @@ static void initGMSKRotationTables() revPtr = GMSKReverseRotation1->begin(); phase = 0.0; while (rotPtr != GMSKRotation1->end()) { - *rotPtr++ = expjLookup(phase); - *revPtr++ = expjLookup(-phase); - phase += M_PI_F / 2.0F; + *rotPtr++ = complex(cos(phase), sin(phase)); + *revPtr++ = complex(cos(-phase), sin(-phase)); + phase += M_PI / 2.0; } } @@ -1887,7 +1860,6 @@ SoftVector *demodAnyBurst(const signalVector &burst, int sps, complex amp, bool sigProcLibSetup() { - initTrigTables(); generateSincTable(); initGMSKRotationTables(); |