alexbrandmeyer@685: //
alexbrandmeyer@685: //  car.h
alexbrandmeyer@685: //  CARFAC Open Source C++ Library
alexbrandmeyer@685: //
alexbrandmeyer@685: //  Created by Alex Brandmeyer on 5/10/13.
alexbrandmeyer@685: //
alexbrandmeyer@685: // This C++ file is part of an implementation of Lyon's cochlear model:
alexbrandmeyer@685: // "Cascade of Asymmetric Resonators with Fast-Acting Compression"
alexbrandmeyer@685: // to supplement Lyon's upcoming book "Human and Machine Hearing"
alexbrandmeyer@685: //
alexbrandmeyer@685: // Licensed under the Apache License, Version 2.0 (the "License");
alexbrandmeyer@685: // you may not use this file except in compliance with the License.
alexbrandmeyer@685: // You may obtain a copy of the License at
alexbrandmeyer@685: //
alexbrandmeyer@685: //     http://www.apache.org/licenses/LICENSE-2.0
alexbrandmeyer@685: //
alexbrandmeyer@685: // Unless required by applicable law or agreed to in writing, software
alexbrandmeyer@685: // distributed under the License is distributed on an "AS IS" BASIS,
alexbrandmeyer@685: // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
alexbrandmeyer@685: // See the License for the specific language governing permissions and
alexbrandmeyer@685: // limitations under the License.
alexbrandmeyer@685: 
alexbrandmeyer@685: #ifndef CARFAC_CAR_H
alexbrandmeyer@685: #define CARFAC_CAR_H
alexbrandmeyer@685: 
alexbrandmeyer@685: #include "common.h"
alexbrandmeyer@685: 
alexbrandmeyer@685: // A CARParams structure stores the necessary information needed by a CARFAC
ronw@688: // object to design the set of CARCoeffs implementing 'The Cascade of
alexbrandmeyer@685: // Asymmetric Resonators' described in the chapter of the same name in Lyon's
ronw@688: // book "Human and Machine Hearing".
alexbrandmeyer@685: struct CARParams {
alexbrandmeyer@685:   CARParams() {
alexbrandmeyer@685:     velocity_scale = 0.1;
alexbrandmeyer@685:     v_offset = 0.04;
alexbrandmeyer@685:     min_zeta = 0.1;
alexbrandmeyer@685:     max_zeta = 0.35;
alexbrandmeyer@685:     first_pole_theta = 0.85 * kPi;
alexbrandmeyer@685:     zero_ratio = sqrt(2.0);
alexbrandmeyer@685:     high_f_damping_compression = 0.5;
alexbrandmeyer@685:     erb_per_step = 0.5;
alexbrandmeyer@685:     min_pole_hz = 30;
ronw@688:     erb_break_freq = 165.3;  // The Greenwood map's break frequency in Hertz.
ronw@688:     // Glassberg and Moore's high-cf ratio.
ronw@688:     erb_q = 1000 / (24.7 * 4.37);
ronw@688:   }
ronw@688: 
ronw@688:   FPType velocity_scale;  // Used for the velocity nonlinearity.
alexbrandmeyer@685:   FPType v_offset;  // The offset gives us quadratic part.
ronw@688:   FPType min_zeta;  // The minimum damping factor in mid-freq channels.
ronw@688:   FPType max_zeta;  // The maximum damping factor in mid-freq channels.
alexbrandmeyer@685:   FPType first_pole_theta;
alexbrandmeyer@685:   FPType zero_ratio;  // This is how far zero is above the pole.
alexbrandmeyer@685:   FPType high_f_damping_compression;  // A range from 0 to 1 to compress theta.
alexbrandmeyer@685:   FPType erb_per_step;
alexbrandmeyer@685:   FPType min_pole_hz;
alexbrandmeyer@685:   FPType erb_break_freq;
alexbrandmeyer@685:   FPType erb_q;
alexbrandmeyer@685: };
alexbrandmeyer@685: 
ronw@688: // CAR filter coefficients, which are derived from a set of CARParams.
alexbrandmeyer@685: struct CARCoeffs {
alexbrandmeyer@685:   FPType velocity_scale;
alexbrandmeyer@685:   FPType v_offset;
alexbrandmeyer@685:   ArrayX r1_coeffs;
alexbrandmeyer@685:   ArrayX a0_coeffs;
alexbrandmeyer@685:   ArrayX c0_coeffs;
alexbrandmeyer@685:   ArrayX h_coeffs;
alexbrandmeyer@685:   ArrayX g0_coeffs;
alexbrandmeyer@685:   ArrayX zr_coeffs;
alexbrandmeyer@685: };
alexbrandmeyer@685: 
alexbrandmeyer@685: 
ronw@688: // CAR filter state.
alexbrandmeyer@685: struct CARState {
alexbrandmeyer@685:   ArrayX z1_memory;
alexbrandmeyer@685:   ArrayX z2_memory;
alexbrandmeyer@685:   ArrayX za_memory;
alexbrandmeyer@685:   ArrayX zb_memory;
alexbrandmeyer@685:   ArrayX dzb_memory;
alexbrandmeyer@685:   ArrayX zy_memory;
alexbrandmeyer@685:   ArrayX g_memory;
alexbrandmeyer@685:   ArrayX dg_memory;
alexbrandmeyer@685: };
alexbrandmeyer@685: 
ronw@688: #endif  // CARFAC_CAR_H