diff options
Diffstat (limited to 'plugins/gme/game-music-emu-0.6.0/gme/Fir_Resampler.cpp')
| -rw-r--r-- | plugins/gme/game-music-emu-0.6.0/gme/Fir_Resampler.cpp | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/plugins/gme/game-music-emu-0.6.0/gme/Fir_Resampler.cpp b/plugins/gme/game-music-emu-0.6.0/gme/Fir_Resampler.cpp new file mode 100644 index 00000000..f2c905a9 --- /dev/null +++ b/plugins/gme/game-music-emu-0.6.0/gme/Fir_Resampler.cpp @@ -0,0 +1,199 @@ +// Game_Music_Emu 0.5.5. http://www.slack.net/~ant/ + +#include "Fir_Resampler.h" + +#include <string.h> +#include <stdlib.h> +#include <stdio.h> +#include <math.h> + +/* Copyright (C) 2004-2006 Shay Green. This module is free software; you +can redistribute it and/or modify it under the terms of the GNU Lesser +General Public License as published by the Free Software Foundation; either +version 2.1 of the License, or (at your option) any later version. This +module is distributed in the hope that it will be useful, but WITHOUT ANY +WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS +FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more +details. You should have received a copy of the GNU Lesser General Public +License along with this module; if not, write to the Free Software Foundation, +Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ + +#include "blargg_source.h" + +#undef PI +#define PI 3.1415926535897932384626433832795029 + +static void gen_sinc( double rolloff, int width, double offset, double spacing, double scale, + int count, short* out ) +{ + double const maxh = 256; + double const step = PI / maxh * spacing; + double const to_w = maxh * 2 / width; + double const pow_a_n = pow( rolloff, maxh ); + scale /= maxh * 2; + + double angle = (count / 2 - 1 + offset) * -step; + while ( count-- ) + { + *out++ = 0; + double w = angle * to_w; + if ( fabs( w ) < PI ) + { + double rolloff_cos_a = rolloff * cos( angle ); + double num = 1 - rolloff_cos_a - + pow_a_n * cos( maxh * angle ) + + pow_a_n * rolloff * cos( (maxh - 1) * angle ); + double den = 1 - rolloff_cos_a - rolloff_cos_a + rolloff * rolloff; + double sinc = scale * num / den - scale; + + out [-1] = (short) (cos( w ) * sinc + sinc); + } + angle += step; + } +} + +Fir_Resampler_::Fir_Resampler_( int width, sample_t* impulses_ ) : + width_( width ), + write_offset( width * stereo - stereo ), + impulses( impulses_ ) +{ + write_pos = 0; + res = 1; + imp_phase = 0; + skip_bits = 0; + step = stereo; + ratio_ = 1.0; +} + +Fir_Resampler_::~Fir_Resampler_() { } + +void Fir_Resampler_::clear() +{ + imp_phase = 0; + if ( buf.size() ) + { + write_pos = &buf [write_offset]; + memset( buf.begin(), 0, write_offset * sizeof buf [0] ); + } +} + +blargg_err_t Fir_Resampler_::buffer_size( int new_size ) +{ + RETURN_ERR( buf.resize( new_size + write_offset ) ); + clear(); + return 0; +} + +double Fir_Resampler_::time_ratio( double new_factor, double rolloff, double gain ) +{ + ratio_ = new_factor; + + double fstep = 0.0; + { + double least_error = 2; + double pos = 0; + res = -1; + for ( int r = 1; r <= max_res; r++ ) + { + pos += ratio_; + double nearest = floor( pos + 0.5 ); + double error = fabs( pos - nearest ); + if ( error < least_error ) + { + res = r; + fstep = nearest / res; + least_error = error; + } + } + } + + skip_bits = 0; + + step = stereo * (int) floor( fstep ); + + ratio_ = fstep; + fstep = fmod( fstep, 1.0 ); + + double filter = (ratio_ < 1.0) ? 1.0 : 1.0 / ratio_; + double pos = 0.0; + input_per_cycle = 0; + for ( int i = 0; i < res; i++ ) + { + gen_sinc( rolloff, int (width_ * filter + 1) & ~1, pos, filter, + double (0x7FFF * gain * filter), + (int) width_, impulses + i * width_ ); + + pos += fstep; + input_per_cycle += step; + if ( pos >= 0.9999999 ) + { + pos -= 1.0; + skip_bits |= 1 << i; + input_per_cycle++; + } + } + + clear(); + + return ratio_; +} + +int Fir_Resampler_::input_needed( blargg_long output_count ) const +{ + blargg_long input_count = 0; + + unsigned long skip = skip_bits >> imp_phase; + int remain = res - imp_phase; + while ( (output_count -= 2) > 0 ) + { + input_count += step + (skip & 1) * stereo; + skip >>= 1; + if ( !--remain ) + { + skip = skip_bits; + remain = res; + } + output_count -= 2; + } + + long input_extra = input_count - (write_pos - &buf [(width_ - 1) * stereo]); + if ( input_extra < 0 ) + input_extra = 0; + return input_extra; +} + +int Fir_Resampler_::avail_( blargg_long input_count ) const +{ + int cycle_count = input_count / input_per_cycle; + int output_count = cycle_count * res * stereo; + input_count -= cycle_count * input_per_cycle; + + blargg_ulong skip = skip_bits >> imp_phase; + int remain = res - imp_phase; + while ( input_count >= 0 ) + { + input_count -= step + (skip & 1) * stereo; + skip >>= 1; + if ( !--remain ) + { + skip = skip_bits; + remain = res; + } + output_count += 2; + } + return output_count; +} + +int Fir_Resampler_::skip_input( long count ) +{ + int remain = write_pos - buf.begin(); + int max_count = remain - width_ * stereo; + if ( count > max_count ) + count = max_count; + + remain -= count; + write_pos = &buf [remain]; + memmove( buf.begin(), &buf [count], remain * sizeof buf [0] ); + + return count; +} |