comparison trunk/matlab/bmm/carfac/CARFAC_Init.m @ 516:68c15d43fcc8

Added MATLAB code for Lyon's CAR-FAC filter cascade.

+% Copyright 2012, Google, Inc.
+% Author: Richard F. Lyon
+%
+% This Matlab file is part of an implementation of Lyon's cochlear model:
+% "Cascade of Asymmetric Resonators with Fast-Acting Compression"
+% to supplement Lyon's upcoming book "Human and Machine Hearing"
+%
+% 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.
+
+function CF_struct = CARFAC_Init(CF_struct, n_mics)
+% function CF_struct = CARFAC_Init(CF_struct, n_mics)
+%
+% Initialize state for n_mics channels (default 1).
+% This allocates and zeros all the state vector storage in the CF_struct.
+
+% TODO (dicklyon): Review whether storing state in the same struct as
+% the design is a good thing, or whether we want another
+% level of object.  I like fewer structs and class types.
+
+if nargin < 2
+  n_mics = 1;  % monaural
+end
+
+% % this is probably what I'd do in the C++ version:
+% if CF_struct.n_mics ~= n_mics;
+%   % free the state and make new number of channels
+%   % make a struct arrray, one element per mic channel, numbered:
+%   for k = 1:n_mics
+%     CF_struct.state(k)  = struct('mic_number', k);
+%   end
+% end
+% But this code doesn't work because I don't understand struct arrays.
+
+% For now I don't ever free anything if n_mics is reduced;
+% so be sure to respect n_mics, not the size of the state struct array.
+
+AGC_time_constants = CF_struct.AGC_params.time_constants;
+n_AGC_stages = length(AGC_time_constants);
+
+CF_struct.n_mics = n_mics;
+CF_struct.k_mod_decim = 0;  % time index phase, cumulative over segments
+
+% This zeroing grows the struct array as needed:
+for mic = 1:n_mics
+  CF_struct.filter_state(mic).z1_memory = zeros(CF_struct.n_ch, 1);
+  CF_struct.filter_state(mic).z2_memory = zeros(CF_struct.n_ch, 1);
+  % cubic loop
+  CF_struct.filter_state(mic).zA_memory = zeros(CF_struct.n_ch, 1);
+  % AGC interp
+  CF_struct.filter_state(mic).zB_memory = zeros(CF_struct.n_ch, 1);
+  % AGC incr
+  CF_struct.filter_state(mic).dzB_memory = zeros(CF_struct.n_ch, 1);
+  CF_struct.filter_state(mic).zY_memory = zeros(CF_struct.n_ch, 1);
+  CF_struct.filter_state(mic).detect_accum = zeros(CF_struct.n_ch, 1);
+  % AGC loop filters' state:
+  % HACK init
+  CF_struct.AGC_state(mic).AGC_memory = zeros(CF_struct.n_ch, n_AGC_stages);
+  CF_struct.AGC_state(mic).AGC_sum = zeros(CF_struct.n_ch, 1);
+  % IHC state:
+  if CF_struct.IHC_coeffs.just_hwr
+    CF_struct.IHC_state(mic).ihc_accum = zeros(CF_struct.n_ch, 1);
+  else
+    CF_struct.IHC_state(mic).cap_voltage = ...
+      CF_struct.IHC_coeffs(mic).rest_cap * ones(CF_struct.n_ch, 1);
+    CF_struct.IHC_state(mic).cap1_voltage = ...
+      CF_struct.IHC_coeffs(mic).rest_cap1 * ones(CF_struct.n_ch, 1);
+    CF_struct.IHC_state(mic).cap2_voltage = ...
+      CF_struct.IHC_coeffs(mic).rest_cap2 * ones(CF_struct.n_ch, 1);
+    CF_struct.IHC_state(mic).lpf1_state = ...
+      CF_struct.IHC_coeffs(mic).rest_output * zeros(CF_struct.n_ch, 1);
+    CF_struct.IHC_state(mic).lpf2_state = ...
+      CF_struct.IHC_coeffs(mic).rest_output * zeros(CF_struct.n_ch, 1);
+    CF_struct.IHC_state(mic).ihc_accum = zeros(CF_struct.n_ch, 1);
+  end
+end
+
+