303 lines
7.8 KiB
C++
303 lines
7.8 KiB
C++
/*****************************************************************************
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Downsampler2xFpu.hpp
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Author: Laurent de Soras, 2005
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--- Legal stuff ---
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This program is free software. It comes without any warranty, to
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the extent permitted by applicable law. You can redistribute it
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and/or modify it under the terms of the Do What The Fuck You Want
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To Public License, Version 2, as published by Sam Hocevar. See
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http://sam.zoy.org/wtfpl/COPYING for more details.
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*Tab=3***********************************************************************/
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#if defined (hiir_Downsampler2xFpu_CURRENT_CODEHEADER)
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#error Recursive inclusion of Downsampler2xFpu code header.
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#endif
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#define hiir_Downsampler2xFpu_CURRENT_CODEHEADER
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#if ! defined (hiir_Downsampler2xFpu_CODEHEADER_INCLUDED)
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#define hiir_Downsampler2xFpu_CODEHEADER_INCLUDED
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/*\\\ INCLUDE FILES \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
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#include "hiir/StageProcFpu.h"
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#include <cassert>
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namespace hiir
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{
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/*\\\ PUBLIC \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
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/*
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==============================================================================
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Name: ctor
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Throws: Nothing
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==============================================================================
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*/
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template <int NC>
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Downsampler2xFpu <NC>::Downsampler2xFpu ()
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: _coef ()
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, _x ()
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, _y ()
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{
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for (int i = 0; i < NBR_COEFS; ++i)
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{
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_coef [i] = 0;
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}
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clear_buffers ();
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}
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/*
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==============================================================================
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Name: set_coefs
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Description:
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Sets filter coefficients. Generate them with the PolyphaseIir2Designer
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class.
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Call this function before doing any processing.
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Input parameters:
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- coef_arr: Array of coefficients. There should be as many coefficients as
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mentioned in the class template parameter.
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Throws: Nothing
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==============================================================================
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*/
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template <int NC>
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void Downsampler2xFpu <NC>::set_coefs (const double coef_arr [])
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{
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assert (coef_arr != 0);
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for (int i = 0; i < NBR_COEFS; ++i)
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{
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_coef [i] = float (coef_arr [i]);
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}
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}
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/*
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==============================================================================
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Name: process_sample
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Description:
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Downsamples (x2) one pair of samples, to generate one output sample.
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Input parameters:
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- in_ptr: pointer on the two samples to decimate
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Returns: Samplerate-reduced sample.
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Throws: Nothing
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==============================================================================
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*/
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template <int NC>
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float Downsampler2xFpu <NC>::process_sample (const float in_ptr [2])
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{
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assert (in_ptr != 0);
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float spl_0 (in_ptr [1]);
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float spl_1 (in_ptr [0]);
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#if defined (_MSC_VER)
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#pragma inline_depth (255)
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#endif // _MSC_VER
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StageProcFpu <NBR_COEFS>::process_sample_pos (
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NBR_COEFS,
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spl_0,
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spl_1,
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&_coef [0],
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&_x [0],
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&_y [0]
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);
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return 0.5f * (spl_0 + spl_1);
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}
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/*
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==============================================================================
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Name: process_block
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Description:
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Downsamples (x2) a block of samples.
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Input and output blocks may overlap, see assert() for details.
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Input parameters:
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- in_ptr: Input array, containing nbr_spl * 2 samples.
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- nbr_spl: Number of samples to output, > 0
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Output parameters:
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- out_ptr: Array for the output samples, capacity: nbr_spl samples.
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Throws: Nothing
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==============================================================================
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*/
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template <int NC>
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void Downsampler2xFpu <NC>::process_block (float out_ptr [], const float in_ptr [], long nbr_spl)
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{
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assert (in_ptr != 0);
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assert (out_ptr != 0);
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assert (out_ptr <= in_ptr || out_ptr >= in_ptr + nbr_spl * 2);
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assert (nbr_spl > 0);
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long pos = 0;
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do
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{
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out_ptr [pos] = process_sample (&in_ptr [pos * 2]);
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++pos;
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}
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while (pos < nbr_spl);
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}
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/*
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==============================================================================
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Name: process_sample_split
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Description:
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Split (spectrum-wise) in half a pair of samples. The lower part of the
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spectrum is a classic downsampling, equivalent to the output of
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process_sample().
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The higher part is the complementary signal: original filter response
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is flipped from left to right, becoming a high-pass filter with the same
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cutoff frequency. This signal is then critically sampled (decimation by 2),
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flipping the spectrum: Fs/4...Fs/2 becomes Fs/4...0.
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Input parameters:
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- in_ptr: pointer on the pair of input samples
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Output parameters:
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- low: output sample, lower part of the spectrum (downsampling)
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- high: output sample, higher part of the spectrum.
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Throws: Nothing
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==============================================================================
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*/
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template <int NC>
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void Downsampler2xFpu <NC>::process_sample_split (float &low, float &high, const float in_ptr [2])
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{
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assert (in_ptr != 0);
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float spl_0 = in_ptr [1];
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float spl_1 = in_ptr [0];
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#if defined (_MSC_VER)
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#pragma inline_depth (255)
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#endif // _MSC_VER
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StageProcFpu <NBR_COEFS>::process_sample_pos (
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NBR_COEFS,
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spl_0,
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spl_1,
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&_coef [0],
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&_x [0],
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&_y [0]
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);
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low = (spl_0 + spl_1) * 0.5f;
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high = spl_0 - low; // (spl_0 - spl_1) * 0.5f;
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}
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/*
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==============================================================================
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Name: process_block_split
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Description:
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Split (spectrum-wise) in half a block of samples. The lower part of the
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spectrum is a classic downsampling, equivalent to the output of
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process_block().
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The higher part is the complementary signal: original filter response
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is flipped from left to right, becoming a high-pass filter with the same
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cutoff frequency. This signal is then critically sampled (decimation by 2),
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flipping the spectrum: Fs/4...Fs/2 becomes Fs/4...0.
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Input and output blocks may overlap, see assert() for details.
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Input parameters:
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- in_ptr: Input array, containing nbr_spl * 2 samples.
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- nbr_spl: Number of samples for each output, > 0
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Output parameters:
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- out_l_ptr: Array for the output samples, lower part of the spectrum
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(downsampling). Capacity: nbr_spl samples.
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- out_h_ptr: Array for the output samples, higher part of the spectrum.
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Capacity: nbr_spl samples.
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Throws: Nothing
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==============================================================================
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*/
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template <int NC>
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void Downsampler2xFpu <NC>::process_block_split (float out_l_ptr [], float out_h_ptr [], const float in_ptr [], long nbr_spl)
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{
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assert (in_ptr != 0);
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assert (out_l_ptr != 0);
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assert (out_l_ptr <= in_ptr || out_l_ptr >= in_ptr + nbr_spl * 2);
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assert (out_h_ptr != 0);
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assert (out_h_ptr <= in_ptr || out_h_ptr >= in_ptr + nbr_spl * 2);
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assert (out_h_ptr != out_l_ptr);
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assert (nbr_spl > 0);
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long pos = 0;
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do
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{
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process_sample_split (
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out_l_ptr [pos],
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out_h_ptr [pos],
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&in_ptr [pos * 2]
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);
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++pos;
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}
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while (pos < nbr_spl);
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}
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/*
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==============================================================================
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Name: clear_buffers
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Description:
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Clears filter memory, as if it processed silence since an infinite amount
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of time.
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Throws: Nothing
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==============================================================================
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*/
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template <int NC>
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void Downsampler2xFpu <NC>::clear_buffers ()
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{
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for (int i = 0; i < NBR_COEFS; ++i)
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{
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_x [i] = 0;
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_y [i] = 0;
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}
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}
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/*\\\ PROTECTED \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
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/*\\\ PRIVATE \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
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} // namespace hiir
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#endif // hiir_Downsampler2xFpu_CODEHEADER_INCLUDED
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#undef hiir_Downsampler2xFpu_CURRENT_CODEHEADER
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/*\\\ EOF \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*/
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