Diff: ParametricEQ.h

Revision:

0:2e17a3d6907c

Child:

1:0545d8890dc6

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ParametricEQ.h	Thu Aug 04 19:34:39 2016 +0000
@@ -0,0 +1,199 @@
+/**
+ * @file    ParametricEQ.h
+ * @brief   ParametricEQ - fixed point implementation of a Parametric EQ
+ * @author  Patrick Thomas
+ * @version 1.0
+ * @see
+ *
+ * Copyright (c) 2016
+ *
+ * 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 PARAMETRICEQ_H
+#define PARAMETRICEQ_H
+
+#include <math.h>
+
+#define M_PI 3.14159265358979323846
+
+// Parameter limits
+#define GAIN_DB_MAX 20
+#define BW_HZ_MIN 20
+#define GBW_MARGIN 0.01
+#define MAX_ORDER 4
+
+// Sampling limits
+#define SAMPLE_RATE_MAX 192000
+#define SAMPLE_RATE_MIN 32000
+#define SAMPLE_BITS_MIN 8
+#define SAMPLE_BITS_MAX 24
+
+#define PIN(n,min,max) ((n) > (max) ? max : ((n) < (min) ? (min) : (n)))
+
+/** A fixed point parametric EQ implementing Butterworth coefficients in direct form 2 transposed realisation
+ *
+ * Example:
+ * @code
+ *  #include "mbed.h"
+ *  #include "ParametricEQ.h"
+ *
+ *  ParametricEQ myEQ;
+ *  Serial pc(USBTX, USBRX);
+ *
+ *  int main()
+ *  {
+ *      while(1) {
+ *       
+ *      while(pc.readable()) {
+ *       
+ *          pc.printf("(pc.getc());
+ *      }
+ *          
+ *      }
+ *  }
+ * @endcode
+ */
+
+class biquad {
+    
+private:
+
+    // Local accumulators
+    int v1;
+    int v2;
+    int v3;
+    int v4;
+    int w1;
+    int w2;
+
+public:
+
+    // Local coefficients
+    int c0;
+    int s0;
+    int bhat_0;
+    int bhat_1;
+    int bhat_2;
+    int ahat_1;
+    int ahat_2;
+
+    // Sampling variables
+    int scaling_factor;
+    int sample_bounds;
+
+    int execute(int input);
+};
+
+enum FilterType {
+    
+    Peaking,
+    BandPass,
+    BandStop,
+    LowShelf,
+    HighShelf,
+    LowPass,
+    HighPass    
+};
+
+class ParametricEQ {
+
+    // This module's fx blocks
+    biquad fx_blocks[(MAX_ORDER + 1)/2];
+
+    // Parameter variables
+    float Gain_dB;
+    float GBW_dB;
+    int F0_Hz;
+    int BW_Hz;
+    int Order;
+    FilterType Type;
+    
+    // Sampling variables
+    int Sample_rate;
+    int Sample_bits;
+
+    // Intermediary parameter variables
+    double Gain_amplitude, Bandwidth_gain_amplitude, G0_amplitude, Normalised_centre_frequency, Normalised_bandwidth, 
+            g, epsilon, beta, g_squared, beta_squared, f0_cosine, f0_sine, D, phi, si, g0, g0_squared;
+    int counter;
+    
+    // Intermediary sampling variables
+    int Scaling_factor, Sample_bounds;
+    
+    void check_GBW();
+    void calculate();
+    void update_blocks();
+
+public:
+    
+    /** Create an EQ
+     */
+    ParametricEQ();
+    
+    /** Set the Gain 
+     *  @param value The target gain (dB)
+     *  @return The actual gain (dB)
+     */
+    float set_Gain_dB(float value);
+    
+    /** Set the Bandwidth Gain. NB |GBW_dB| must be less than |Gain_dB|
+     *  @param value The target bandwidth gain (dB)
+     *  @return The actual bandwidth gain (dB)
+     */
+    float set_GBW_dB(float value);
+    
+    /** Set the Centre frequency
+     *  @param value The target centre frequency (Hz)
+     *  @return The actual centre frequency (Hz)
+     */
+    int set_F0_Hz(int value);
+    
+    /** Set the Bandwidth 
+     *  @param value The target bandwidth (Hz)
+     *  @return The actual bandwidth (Hz)
+     */
+    int set_BW_Hz(int value);
+    
+    /** Set the Order. Higher order increases cutoff 
+     *  @param value The target order
+     *  @return The actual order
+     */
+    int set_Order(int value);
+    
+    /** Set the Filter type.
+     *  @param value The target type: 0 - Peaking, 1 - BandPass, 2 - BandStop, 3 - LowShelf, 4 - HighShelf, 5 - LowPass, 6 - HighPass
+     *  @return The actual type
+     */
+    FilterType set_Type(FilterType type);
+    
+    /** Set the Sample rate
+     *  @param value The target sample rate
+     *  @return The actual sample rate
+     */
+    int set_Sample_rate(int value);
+    
+    /** Set the number of Sample bits
+     *  @param value The target number of sample bits
+     *  @return The actual number of sample bits
+     */
+    int set_Sample_bits(int value);
+    
+    /** Pass a sample through the EQ
+     *  @param input The input sample
+     *  @return The filtered output
+     */
+    int filter(int input);
+};
+
+#endif