From a2397729a29d23a63895495b086ee20dcc61280c Mon Sep 17 00:00:00 2001
From: Ahmet Inan <xdsopl@googlemail.com>
Date: Sun, 30 Nov 2014 13:30:50 +0100
Subject: [PATCH] moved ema code to ema.rsh

---
 app/src/main/rs/decoder.rs | 43 ++++++++++++--------------------
 app/src/main/rs/ema.rsh    | 51 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+), 27 deletions(-)
 create mode 100644 app/src/main/rs/ema.rsh

diff --git a/app/src/main/rs/decoder.rs b/app/src/main/rs/decoder.rs
index 2f24821..b167615 100644
--- a/app/src/main/rs/decoder.rs
+++ b/app/src/main/rs/decoder.rs
@@ -18,6 +18,7 @@ limitations under the License.
 #pragma rs java_package_name(xdsopl.robot36)
 
 #include "complex.rsh"
+#include "ema.rsh"
 
 short *audio_buffer;
 uchar *value_buffer;
@@ -25,77 +26,69 @@ uchar4 *pixel_buffer;
 
 static inline uchar4 rgb(uchar r, uchar g, uchar b) { return (uchar4){ b, g, r, 255 }; }
 
-static float ema_a(float cutoff, float rate, int order)
-{
-    float fc = cutoff / sqrt(rootn(2.0f, order) - 1.0f);
-    float RC = 1.0f / (2.0f * M_PI * fc);
-    float dt = 1.0f / rate;
-    return dt / (RC + dt);
-}
-
 static const float ema_estimator_a = 0.7f;
 static int robot36_scanline_length;
 static float robot36_estimator(int length)
 {
     static float variance;
     float deviation = robot36_scanline_length - length;
-    return variance = ema_estimator_a * deviation * deviation + (1.0f - ema_estimator_a) * variance;
+    return ema(&variance, deviation * deviation, ema_estimator_a);
 }
 static int robot72_scanline_length;
 static float robot72_estimator(int length)
 {
     static float variance;
     float deviation = robot72_scanline_length - length;
-    return variance = ema_estimator_a * deviation * deviation + (1.0f - ema_estimator_a) * variance;
+    return ema(&variance, deviation * deviation, ema_estimator_a);
 }
 static int martin1_scanline_length;
 static float martin1_estimator(int length)
 {
     static float variance;
     float deviation = martin1_scanline_length - length;
-    return variance = ema_estimator_a * deviation * deviation + (1.0f - ema_estimator_a) * variance;
+    return ema(&variance, deviation * deviation, ema_estimator_a);
 }
 static int martin2_scanline_length;
 static float martin2_estimator(int length)
 {
     static float variance;
     float deviation = martin2_scanline_length - length;
-    return variance = ema_estimator_a * deviation * deviation + (1.0f - ema_estimator_a) * variance;
+    return ema(&variance, deviation * deviation, ema_estimator_a);
 }
 static int scottie1_scanline_length;
 static float scottie1_estimator(int length)
 {
     static float variance;
     float deviation = scottie1_scanline_length - length;
-    return variance = ema_estimator_a * deviation * deviation + (1.0f - ema_estimator_a) * variance;
+    return ema(&variance, deviation * deviation, ema_estimator_a);
 }
 static int scottie2_scanline_length;
 static float scottie2_estimator(int length)
 {
     static float variance;
     float deviation = scottie2_scanline_length - length;
-    return variance = ema_estimator_a * deviation * deviation + (1.0f - ema_estimator_a) * variance;
+    return ema(&variance, deviation * deviation, ema_estimator_a);
 }
 static int scottieDX_scanline_length;
 static float scottieDX_estimator(int length)
 {
     static float variance;
     float deviation = scottieDX_scanline_length - length;
-    return variance = ema_estimator_a * deviation * deviation + (1.0f - ema_estimator_a) * variance;
+    return ema(&variance, deviation * deviation, ema_estimator_a);
 }
 
 static float ema_power_a;
 static float avg_power(float input)
 {
     static float output;
-    return output = ema_power_a * input + (1.0f - ema_power_a) * output;
+    return ema(&output, input, ema_power_a);
 }
 
 static float ema_leader_a;
 static float leader_lowpass(float input)
 {
     static float output;
-    return output = ema_leader_a * input + (1.0f - ema_leader_a) * output;
+    return ema(&output, input, ema_leader_a);
 }
 
 static const int filter_order = 11;
@@ -103,18 +96,14 @@ static float ema_cnt_a;
 static complex_t cnt_lowpass(complex_t input)
 {
     static complex_t output[filter_order];
-    for (int i = 0; i < filter_order; ++i)
-        output[i] = input = ema_cnt_a * input + (1.0f - ema_cnt_a) * output[i];
-    return input;
+    return cema_cascade(output, input, ema_cnt_a, filter_order);
 }
 
 static float ema_dat_a;
 static complex_t dat_lowpass(complex_t input)
 {
     static complex_t output[filter_order];
-    for (int i = 0; i < filter_order; ++i)
-        output[i] = input = ema_dat_a * input + (1.0f - ema_dat_a) * output[i];
-    return input;
+    return cema_cascade(output, input, ema_dat_a, filter_order);
 }
 
 static complex_t cnt_phasor, cnt_phasor_delta;
@@ -450,10 +439,10 @@ void initialize(float rate, int length, int width, int height)
     const float dat_bandwidth = 800.0f;
     const float cnt_bandwidth = 200.0f;
 
-    ema_power_a = ema_a(10.0f, sample_rate, 1);
-    ema_leader_a = ema_a(100.0f, sample_rate, 1);
-    ema_cnt_a = ema_a(cnt_bandwidth, sample_rate, filter_order);
-    ema_dat_a = ema_a(dat_bandwidth, sample_rate, filter_order);
+    ema_power_a = ema_a(10.0f, sample_rate);
+    ema_leader_a = ema_a(100.0f, sample_rate);
+    ema_cnt_a = ema_cascade_a(cnt_bandwidth, sample_rate, filter_order);
+    ema_dat_a = ema_cascade_a(dat_bandwidth, sample_rate, filter_order);
 
     cnt_phasor = complex(0.0f, 1.0f);
     cnt_phasor_delta = cexp(complex(0.0f, -2.0f * M_PI * cnt_carrier / sample_rate));
diff --git a/app/src/main/rs/ema.rsh b/app/src/main/rs/ema.rsh
new file mode 100644
index 0000000..651f797
--- /dev/null
+++ b/app/src/main/rs/ema.rsh
@@ -0,0 +1,51 @@
+/*
+Copyright 2014 Ahmet Inan <xdsopl@googlemail.com>
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+ */
+
+#ifndef EMA_RSH
+#define EMA_RSH
+
+#include "complex.rsh"
+
+static float ema_a(float cutoff, float rate)
+{
+    float RC = 1.0f / (2.0f * M_PI * cutoff);
+    float dt = 1.0f / rate;
+    return dt / (RC + dt);
+}
+
+static float ema_cascade_a(float cutoff, float rate, int order)
+{
+    return ema_a(cutoff / sqrt(rootn(2.0f, order) - 1.0f), rate);
+}
+
+static inline float ema(float *output, float input, float a)
+{
+    return *output = a * input + (1.0f - a) * *output;
+}
+
+static inline complex_t cema(complex_t *output, complex_t input, float a)
+{
+    return *output = a * input + (1.0f - a) * *output;
+}
+
+static complex_t cema_cascade(complex_t *output, complex_t input, float a, int order)
+{
+    for (int i = 0; i < order; ++i)
+        input = cema(output + i, input, a);
+    return input;
+}
+
+#endif
\ No newline at end of file