From 3479559859be870043a38b48c930840ab862475a Mon Sep 17 00:00:00 2001
From: f4exb <f4exb06@gmail.com>
Date: Tue, 3 Jan 2017 23:25:20 +0100
Subject: [PATCH] Tx support: optimize final interpolator stages

---
 sdrbase/dsp/hbfiltertraits.cpp | 12 ++++++++++++
 sdrbase/dsp/hbfiltertraits.h   |  9 +++++++++
 sdrbase/dsp/interpolators.h    | 28 +++++++++++++++-------------
 3 files changed, 36 insertions(+), 13 deletions(-)

diff --git a/sdrbase/dsp/hbfiltertraits.cpp b/sdrbase/dsp/hbfiltertraits.cpp
index 61d15f6a9..4d9241239 100644
--- a/sdrbase/dsp/hbfiltertraits.cpp
+++ b/sdrbase/dsp/hbfiltertraits.cpp
@@ -18,6 +18,18 @@
 
 #include "dsp/hbfiltertraits.h"
 
+const int16_t HBFIRFilterTraits<16>::hbMod[16+6] = {
+        15,16,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,0,1,2
+};
+
+const int32_t HBFIRFilterTraits<16>::hbCoeffs[4] = {
+        //* Firwin as in https://www.dsprelated.com/showcode/270.php */
+        (int32_t)(-0.0052391810630145274965685509016566356877 * (1 << hbShift)),
+        (int32_t)(0.0232111017863650750947535073009930783883 * (1 << hbShift)),
+        (int32_t)(-0.0761058457486735451258397233686991967261 * (1 << hbShift)),
+        (int32_t)(0.3076987787367443383246268240327481180429 * (1 << hbShift)),
+};
+
 const int16_t HBFIRFilterTraits<32>::hbMod[32+6] = {
         31,32,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19, 20,21,22,
         23,24,25,26,27,28,29,30,31,32,0,1,2
diff --git a/sdrbase/dsp/hbfiltertraits.h b/sdrbase/dsp/hbfiltertraits.h
index 14bbb266c..278f202a2 100644
--- a/sdrbase/dsp/hbfiltertraits.h
+++ b/sdrbase/dsp/hbfiltertraits.h
@@ -31,6 +31,15 @@ struct HBFIRFilterTraits
 {
 };
 
+template<>
+struct HBFIRFilterTraits<16>
+{
+    static const int32_t hbOrder = 16;
+    static const int32_t hbShift = 14;
+    static const int16_t hbMod[16+6];
+    static const int32_t hbCoeffs[4] __attribute__ ((aligned (16)));
+};
+
 template<>
 struct HBFIRFilterTraits<32>
 {
diff --git a/sdrbase/dsp/interpolators.h b/sdrbase/dsp/interpolators.h
index a4faae1a3..24f49a5b7 100644
--- a/sdrbase/dsp/interpolators.h
+++ b/sdrbase/dsp/interpolators.h
@@ -24,7 +24,9 @@
 #include "dsp/inthalfbandfilterdb.h"
 #endif
 
-#define INTERPOLATORS_HB_FILTER_ORDER 64
+#define INTERPOLATORS_HB_FILTER_ORDER_FIRST  64
+#define INTERPOLATORS_HB_FILTER_ORDER_SECOND 32
+#define INTERPOLATORS_HB_FILTER_ORDER_NEXT   16
 
 template<uint SdrBits, uint OutputBits>
 struct interpolation_shifts
@@ -113,19 +115,19 @@ public:
 
 private:
 #ifdef USE_SSE4_1
-    IntHalfbandFilterEO1<INTERPOLATORS_HB_FILTER_ORDER> m_interpolator2;  // 1st stages
-    IntHalfbandFilterEO1<INTERPOLATORS_HB_FILTER_ORDER> m_interpolator4;  // 2nd stages
-    IntHalfbandFilterEO1<INTERPOLATORS_HB_FILTER_ORDER> m_interpolator8;  // 3rd stages
-    IntHalfbandFilterEO1<INTERPOLATORS_HB_FILTER_ORDER> m_interpolator16; // 4th stages
-    IntHalfbandFilterEO1<INTERPOLATORS_HB_FILTER_ORDER> m_interpolator32; // 5th stages
-    IntHalfbandFilterEO1<INTERPOLATORS_HB_FILTER_ORDER> m_interpolator64; // 6th stages
+    IntHalfbandFilterEO1<INTERPOLATORS_HB_FILTER_ORDER_FIRST> m_interpolator2;  // 1st stages
+    IntHalfbandFilterEO1<INTERPOLATORS_HB_FILTER_ORDER_SECOND> m_interpolator4;  // 2nd stages
+    IntHalfbandFilterEO1<INTERPOLATORS_HB_FILTER_ORDER_NEXT> m_interpolator8;  // 3rd stages
+    IntHalfbandFilterEO1<INTERPOLATORS_HB_FILTER_ORDER_NEXT> m_interpolator16; // 4th stages
+    IntHalfbandFilterEO1<INTERPOLATORS_HB_FILTER_ORDER_NEXT> m_interpolator32; // 5th stages
+    IntHalfbandFilterEO1<INTERPOLATORS_HB_FILTER_ORDER_NEXT> m_interpolator64; // 6th stages
 #else
-	IntHalfbandFilterDB<INTERPOLATORS_HB_FILTER_ORDER> m_interpolator2;  // 1st stages
-	IntHalfbandFilterDB<INTERPOLATORS_HB_FILTER_ORDER> m_interpolator4;  // 2nd stages
-	IntHalfbandFilterDB<INTERPOLATORS_HB_FILTER_ORDER> m_interpolator8;  // 3rd stages
-	IntHalfbandFilterDB<INTERPOLATORS_HB_FILTER_ORDER> m_interpolator16; // 4th stages
-	IntHalfbandFilterDB<INTERPOLATORS_HB_FILTER_ORDER> m_interpolator32; // 5th stages
-	IntHalfbandFilterDB<INTERPOLATORS_HB_FILTER_ORDER> m_interpolator64; // 6th stages
+	IntHalfbandFilterDB<INTERPOLATORS_HB_FILTER_ORDER_FIRST> m_interpolator2;  // 1st stages
+	IntHalfbandFilterDB<INTERPOLATORS_HB_FILTER_ORDER_SECOND> m_interpolator4;  // 2nd stages
+	IntHalfbandFilterDB<INTERPOLATORS_HB_FILTER_ORDER_NEXT> m_interpolator8;  // 3rd stages
+	IntHalfbandFilterDB<INTERPOLATORS_HB_FILTER_ORDER_NEXT> m_interpolator16; // 4th stages
+	IntHalfbandFilterDB<INTERPOLATORS_HB_FILTER_ORDER_NEXT> m_interpolator32; // 5th stages
+	IntHalfbandFilterDB<INTERPOLATORS_HB_FILTER_ORDER_NEXT> m_interpolator64; // 6th stages
 #endif
 };