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LaiNES/src/Blip_Synth.h

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2014-06-01 12:29:22 +00:00
// Blip_Synth and Blip_Wave are waveform transition synthesizers for adding
// waveforms to a Blip_Buffer.
// Blip_Buffer 0.3.3. Copyright (C) 2003-2005 Shay Green. GNU LGPL license.
#ifndef BLIP_SYNTH_H
#define BLIP_SYNTH_H
#ifndef BLIP_BUFFER_H
#include "Blip_Buffer.h"
#endif
// Quality level. Higher levels are slower, and worse in a few cases.
// Use blip_good_quality as a starting point.
const int blip_low_quality = 1;
const int blip_med_quality = 2;
const int blip_good_quality = 3;
const int blip_high_quality = 4;
// Blip_Synth is a transition waveform synthesizer which adds band-limited
// offsets (transitions) into a Blip_Buffer. For a simpler interface, use
// Blip_Wave (below).
//
// Range specifies the greatest expected offset that will occur. For a
// waveform that goes between +amp and -amp, range should be amp * 2 (half
// that if it only goes between +amp and 0). When range is large, a higher
// accuracy scheme is used; to force this even when range is small, pass
// the negative of range (i.e. -range).
template<int quality,int range>
class Blip_Synth {
BOOST_STATIC_ASSERT( 1 <= quality && quality <= 5 );
BOOST_STATIC_ASSERT( -32768 <= range && range <= 32767 );
enum {
abs_range = (range < 0) ? -range : range,
fine_mode = (range > 512 || range < 0),
width = (quality < 5 ? quality * 4 : Blip_Buffer::widest_impulse_),
res = 1 << blip_res_bits_,
impulse_size = width / 2 * (fine_mode + 1),
base_impulses_size = width / 2 * (res / 2 + 1),
fine_bits = (fine_mode ? (abs_range <= 64 ? 2 : abs_range <= 128 ? 3 :
abs_range <= 256 ? 4 : abs_range <= 512 ? 5 : abs_range <= 1024 ? 6 :
abs_range <= 2048 ? 7 : 8) : 0)
};
blip_pair_t_ impulses [impulse_size * res * 2 + base_impulses_size];
Blip_Impulse_ impulse;
public:
Blip_Synth() { impulse.init( impulses, width, res, fine_bits ); }
// Configure low-pass filter (see notes.txt). Not optimized for real-time control
void treble_eq( const blip_eq_t& eq ) { impulse.treble_eq( eq ); }
// Set volume of a transition at amplitude 'range' by setting volume_unit
// to v / range
void volume( double v ) { impulse.volume_unit( v * (1.0 / abs_range) ); }
// Set base volume unit of transitions, where 1.0 is a full swing between the
// positive and negative extremes. Not optimized for real-time control.
void volume_unit( double unit ) { impulse.volume_unit( unit ); }
// Default Blip_Buffer used for output when none is specified for a given call
Blip_Buffer* output() const { return impulse.buf; }
void output( Blip_Buffer* b ) { impulse.buf = b; }
// Add an amplitude offset (transition) with a magnitude of delta * volume_unit
// into the specified buffer (default buffer if none specified) at the
// specified source time. Delta can be positive or negative. To increase
// performance by inlining code at the call site, use offset_inline().
void offset( blip_time_t, int delta, Blip_Buffer* ) const;
void offset_resampled( blip_resampled_time_t, int delta, Blip_Buffer* ) const;
void offset_resampled( blip_resampled_time_t t, int o ) const {
offset_resampled( t, o, impulse.buf );
}
void offset( blip_time_t t, int delta ) const {
offset( t, delta, impulse.buf );
}
void offset_inline( blip_time_t time, int delta, Blip_Buffer* buf ) const {
offset_resampled( time * buf->factor_ + buf->offset_, delta, buf );
}
void offset_inline( blip_time_t time, int delta ) const {
offset_inline( time, delta, impulse.buf );
}
};
// Blip_Wave is a synthesizer for adding a *single* waveform to a Blip_Buffer.
// A wave is built from a series of delays and new amplitudes. This provides a
// simpler interface than Blip_Synth, nothing more.
template<int quality,int range>
class Blip_Wave {
Blip_Synth<quality,range> synth;
blip_time_t time_;
int last_amp;
public:
// Start wave at time 0 and amplitude 0
Blip_Wave() : time_( 0 ), last_amp( 0 ) { }
// See Blip_Synth for description
void volume( double v ) { synth.volume( v ); }
void volume_unit( double v ) { synth.volume_unit( v ); }
void treble_eq( const blip_eq_t& eq){ synth.treble_eq( eq ); }
Blip_Buffer* output() const { return synth.output(); }
void output( Blip_Buffer* b ) { synth.output( b ); if ( !b ) time_ = last_amp = 0; }
// Current time in frame
blip_time_t time() const { return time_; }
void time( blip_time_t t ) { time_ = t; }
// Current amplitude of wave
int amplitude() const { return last_amp; }
void amplitude( int );
// Move forward by 't' time units
void delay( blip_time_t t ) { time_ += t; }
// End time frame of specified duration. Localize time to new frame.
void end_frame( blip_time_t duration ) {
assert(( "Blip_Wave::end_frame(): Wave hadn't yet been run for entire frame",
duration <= time_ ));
time_ -= duration;
}
};
// End of public interface
template<int quality,int range>
void Blip_Wave<quality,range>::amplitude( int amp ) {
int delta = amp - last_amp;
last_amp = amp;
synth.offset_inline( time_, delta );
}
template<int quality,int range>
inline void Blip_Synth<quality,range>::offset_resampled( blip_resampled_time_t time,
int delta, Blip_Buffer* blip_buf ) const
{
typedef blip_pair_t_ pair_t;
unsigned sample_index = (time >> BLIP_BUFFER_ACCURACY) & ~1;
assert(( "Blip_Synth/Blip_wave: Went past end of buffer",
sample_index < blip_buf->buffer_size_ ));
enum { const_offset = Blip_Buffer::widest_impulse_ / 2 - width / 2 };
pair_t* buf = (pair_t*) &blip_buf->buffer_ [const_offset + sample_index];
enum { shift = BLIP_BUFFER_ACCURACY - blip_res_bits_ };
enum { mask = res * 2 - 1 };
const pair_t* imp = &impulses [((time >> shift) & mask) * impulse_size];
pair_t offset = impulse.offset * delta;
if ( !fine_bits )
{
// normal mode
for ( int n = width / 4; n; --n )
{
pair_t t0 = buf [0] - offset;
pair_t t1 = buf [1] - offset;
t0 += imp [0] * delta;
t1 += imp [1] * delta;
imp += 2;
buf [0] = t0;
buf [1] = t1;
buf += 2;
}
}
else
{
// fine mode
enum { sub_range = 1 << fine_bits };
delta += sub_range / 2;
int delta2 = (delta & (sub_range - 1)) - sub_range / 2;
delta >>= fine_bits;
for ( int n = width / 4; n; --n )
{
pair_t t0 = buf [0] - offset;
pair_t t1 = buf [1] - offset;
t0 += imp [0] * delta2;
t0 += imp [1] * delta;
t1 += imp [2] * delta2;
t1 += imp [3] * delta;
imp += 4;
buf [0] = t0;
buf [1] = t1;
buf += 2;
}
}
}
template<int quality,int range>
void Blip_Synth<quality,range>::offset( blip_time_t time, int delta, Blip_Buffer* buf ) const {
offset_resampled( time * buf->factor_ + buf->offset_, delta, buf );
}
#endif