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// Game_Music_Emu 0.5.5. http://www.slack.net/~ant/
#include "resampler.h"
#include <stdlib.h>
#include <string.h>
/* Copyright (C) 2003-2006 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"
// TODO: fix this. hack since resampler holds back some output.
unsigned const resampler_extra = 34;
enum { shift = 14 };
int const unit = 1 << shift;
blargg_err_t Resampler_setup( struct Resampler* this, int fm_rate, int fm_gain, int rate, int gain )
{
this->gain_ = (int)( ((1LL << gain_bits) * fm_gain * gain) / FP_ONE_GAIN );
this->step = (int)( ((1LL << shift) * fm_rate) / rate + 1);
this->rate_ = this->step;
return 0;
}
blargg_err_t Resampler_reset( struct Resampler* this, int pairs )
{
// expand allocations a bit
this->sample_buffer_size = (pairs + (pairs >> 2)) * 2;
Resampler_resize( this, pairs );
this->resampler_size = this->oversamples_per_frame + (this->oversamples_per_frame >> 2);
this->buffer_size = this->resampler_size;
this->pos = 0;
this->write_pos = 0;
Resampler_clear( this );
return 0;
}
void Resampler_resize( struct Resampler* this, int pairs )
{
int new_sample_buf_size = pairs * 2;
if ( this->sample_buf_size != new_sample_buf_size )
{
if ( new_sample_buf_size > this->sample_buffer_size )
{
check(false);
return;
}
this->sample_buf_size = new_sample_buf_size;
this->oversamples_per_frame = (int) ((pairs * this->rate_ * 2LL) / unit) + 2;
Resampler_clear( this );
}
}
static void mix_samples( struct Resampler* this, struct Blip_Buffer* blip_buf, dsample_t out_ [] )
{
int const bass = BLIP_READER_BASS( *blip_buf );
BLIP_READER_BEGIN( sn, *blip_buf );
int count = this->sample_buf_size >> 1;
BLIP_READER_ADJ_( sn, count );
typedef dsample_t stereo_dsample_t [2];
stereo_dsample_t* BLARGG_RESTRICT out = (stereo_dsample_t*) out_ + count;
stereo_dsample_t const* BLARGG_RESTRICT in =
(stereo_dsample_t const*) this->sample_buf + count;
int offset = -count;
int const gain = this->gain_;
do
{
int s = BLIP_READER_READ_RAW( sn ) >> (blip_sample_bits - 16);
BLIP_READER_NEXT_IDX_( sn, bass, offset );
int l = (in [offset] [0] * gain >> gain_bits) + s;
int r = (in [offset] [1] * gain >> gain_bits) + s;
BLIP_CLAMP( l, l );
out [offset] [0] = (blip_sample_t) l;
BLIP_CLAMP( r, r );
out [offset] [1] = (blip_sample_t) r;
}
while ( ++offset );
BLIP_READER_END( sn, *blip_buf );
}
static dsample_t const* resample_( struct Resampler* this, dsample_t** out_,
dsample_t const* out_end, dsample_t const in [], int in_size )
{
in_size -= write_offset;
if ( in_size > 0 )
{
dsample_t* BLARGG_RESTRICT out = *out_;
dsample_t const* const in_end = in + in_size;
int const step = this->step;
int pos = this->pos;
// TODO: IIR filter, then linear resample
// TODO: detect skipped sample, allowing merging of IIR and resample?
do
{
#define INTERP( i, out )\
out = (in [0 + i] * (unit - pos) + ((in [2 + i] + in [4 + i] + in [6 + i]) << shift) +\
in [8 + i] * pos) >> (shift + 2);
int out_0;
INTERP( 0, out_0 )
INTERP( 1, out [0] = out_0; out [1] )
out += stereo;
pos += step;
in += ((unsigned) pos >> shift) * stereo;
pos &= unit - 1;
}
while ( in < in_end && out < out_end );
this->pos = pos;
*out_ = out;
}
return in;
}
static inline int resample_wrapper( struct Resampler* this, dsample_t out [], int* out_size,
dsample_t const in [], int in_size )
{
assert( Resampler_rate( this ) );
dsample_t* out_ = out;
int result = resample_( this, &out_, out + *out_size, in, in_size ) - in;
assert( out_ <= out + *out_size );
assert( result <= in_size );
*out_size = out_ - out;
return result;
}
static int skip_input( struct Resampler* this, int count )
{
this->write_pos -= count;
if ( this->write_pos < 0 ) // occurs when downsampling
{
count += this->write_pos;
this->write_pos = 0;
}
memmove( this->buf, &this->buf [count], this->write_pos * sizeof this->buf [0] );
return count;
}
static void play_frame_( struct Resampler* this, struct Blip_Buffer* blip_buf, dsample_t* out )
{
int pair_count = this->sample_buf_size >> 1;
blip_time_t blip_time = Blip_count_clocks( blip_buf, pair_count );
int sample_count = this->oversamples_per_frame - this->write_pos + resampler_extra;
int new_count = this->callback( this->callback_data, blip_time, sample_count, &this->buf [this->write_pos] );
assert( new_count < this->resampler_size );
Blip_end_frame( blip_buf, blip_time );
assert( Blip_samples_avail( blip_buf ) == pair_count );
this->write_pos += new_count;
assert( (unsigned) this->write_pos <= this->buffer_size );
int count = this->sample_buf_size;
if ( count )
skip_input( this, resample_wrapper( this, this->sample_buf, &count, this->buf, this->write_pos ) );
assert( count == this->sample_buf_size );
mix_samples( this, blip_buf, out );
Blip_remove_samples( blip_buf, pair_count );
}
void Resampler_play( struct Resampler* this, int count, dsample_t* out, struct Blip_Buffer* blip_buf )
{
// empty extra buffer
int remain = this->sample_buf_size - this->buf_pos;
if ( remain )
{
if ( remain > count )
remain = count;
count -= remain;
memcpy( out, &this->sample_buf [this->buf_pos], remain * sizeof *out );
out += remain;
this->buf_pos += remain;
}
// entire frames
while ( count >= this->sample_buf_size )
{
play_frame_( this, blip_buf, out );
out += this->sample_buf_size;
count -= this->sample_buf_size;
}
// extra
if ( count )
{
play_frame_( this, blip_buf, this->sample_buf );
this->buf_pos = count;
memcpy( out, this->sample_buf, count * sizeof *out );
out += count;
}
}
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