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489 lines
16 KiB
C
489 lines
16 KiB
C
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// Band-limited sound synthesis buffer
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// Blip_Buffer 0.4.1
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#ifndef BLIP_BUFFER_H
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#define BLIP_BUFFER_H
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// internal
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#include <limits.h>
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#if INT_MAX < 0x7FFFFFFF
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#error "int must be at least 32 bits"
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#endif
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typedef int blip_long;
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typedef unsigned blip_ulong;
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// Time unit at source clock rate
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typedef blip_long blip_time_t;
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// Output samples are 16-bit signed, with a range of -32768 to 32767
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typedef short blip_sample_t;
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enum { blip_sample_max = 32767 };
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class Blip_Buffer {
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public:
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typedef const char* blargg_err_t;
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// Set output sample rate and buffer length in milliseconds (1/1000 sec, defaults
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// to 1/4 second), then clear buffer. Returns NULL on success, otherwise if there
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// isn't enough memory, returns error without affecting current buffer setup.
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blargg_err_t set_sample_rate( long samples_per_sec, int msec_length = 1000 / 4 );
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// Set number of source time units per second
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void clock_rate( long );
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// End current time frame of specified duration and make its samples available
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// (along with any still-unread samples) for reading with read_samples(). Begins
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// a new time frame at the end of the current frame.
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void end_frame( blip_time_t time );
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// Read at most 'max_samples' out of buffer into 'dest', removing them from from
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// the buffer. Returns number of samples actually read and removed. If stereo is
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// true, increments 'dest' one extra time after writing each sample, to allow
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// easy interleving of two channels into a stereo output buffer.
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long read_samples( blip_sample_t* dest, long max_samples, int stereo = 0 );
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// Additional optional features
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// Current output sample rate
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long sample_rate() const;
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// Length of buffer, in milliseconds
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int length() const;
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// Number of source time units per second
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long clock_rate() const;
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// Set frequency high-pass filter frequency, where higher values reduce bass more
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void bass_freq( int frequency );
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// Number of samples delay from synthesis to samples read out
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int output_latency() const;
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// Remove all available samples and clear buffer to silence. If 'entire_buffer' is
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// false, just clears out any samples waiting rather than the entire buffer.
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void clear( int entire_buffer = 1 );
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// Number of samples available for reading with read_samples()
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long samples_avail() const;
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// Remove 'count' samples from those waiting to be read
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void remove_samples( long count );
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// Experimental features
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// Count number of clocks needed until 'count' samples will be available.
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// If buffer can't even hold 'count' samples, returns number of clocks until
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// buffer becomes full.
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blip_time_t count_clocks( long count ) const;
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// Number of raw samples that can be mixed within frame of specified duration.
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long count_samples( blip_time_t duration ) const;
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// Mix 'count' samples from 'buf' into buffer.
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void mix_samples( blip_sample_t const* buf, long count );
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// not documented yet
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void set_modified() { modified_ = 1; }
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int clear_modified() { int b = modified_; modified_ = 0; return b; }
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typedef blip_ulong blip_resampled_time_t;
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void remove_silence( long count );
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blip_resampled_time_t resampled_duration( int t ) const { return t * factor_; }
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blip_resampled_time_t resampled_time( blip_time_t t ) const { return t * factor_ + offset_; }
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blip_resampled_time_t clock_rate_factor( long clock_rate ) const;
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public:
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Blip_Buffer();
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~Blip_Buffer();
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// Deprecated
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typedef blip_resampled_time_t resampled_time_t;
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blargg_err_t sample_rate( long r ) { return set_sample_rate( r ); }
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blargg_err_t sample_rate( long r, int msec ) { return set_sample_rate( r, msec ); }
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private:
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// noncopyable
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Blip_Buffer( const Blip_Buffer& );
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Blip_Buffer& operator = ( const Blip_Buffer& );
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public:
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typedef blip_time_t buf_t_;
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blip_ulong factor_;
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blip_resampled_time_t offset_;
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buf_t_* buffer_;
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blip_long buffer_size_;
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blip_long reader_accum_;
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int bass_shift_;
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private:
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long sample_rate_;
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long clock_rate_;
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int bass_freq_;
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int length_;
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int modified_;
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friend class Blip_Reader;
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};
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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// Number of bits in resample ratio fraction. Higher values give a more accurate ratio
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// but reduce maximum buffer size.
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#ifndef BLIP_BUFFER_ACCURACY
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#define BLIP_BUFFER_ACCURACY 16
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#endif
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// Number bits in phase offset. Fewer than 6 bits (64 phase offsets) results in
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// noticeable broadband noise when synthesizing high frequency square waves.
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// Affects size of Blip_Synth objects since they store the waveform directly.
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#ifndef BLIP_PHASE_BITS
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#if BLIP_BUFFER_FAST
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#define BLIP_PHASE_BITS 8
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#else
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#define BLIP_PHASE_BITS 6
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#endif
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#endif
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// Internal
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typedef blip_ulong blip_resampled_time_t;
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int const blip_widest_impulse_ = 16;
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int const blip_buffer_extra_ = blip_widest_impulse_ + 2;
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int const blip_res = 1 << BLIP_PHASE_BITS;
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class blip_eq_t;
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class Blip_Synth_Fast_ {
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public:
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Blip_Buffer* buf;
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int last_amp;
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int delta_factor;
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void volume_unit( double );
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Blip_Synth_Fast_();
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void treble_eq( blip_eq_t const& ) { }
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};
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class Blip_Synth_ {
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public:
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Blip_Buffer* buf;
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int last_amp;
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int delta_factor;
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void volume_unit( double );
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Blip_Synth_( short* impulses, int width );
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void treble_eq( blip_eq_t const& );
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private:
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double volume_unit_;
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short* const impulses;
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int const width;
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blip_long kernel_unit;
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int impulses_size() const { return blip_res / 2 * width + 1; }
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void adjust_impulse();
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};
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// Quality level. Start with blip_good_quality.
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const int blip_med_quality = 8;
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const int blip_good_quality = 12;
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const int blip_high_quality = 16;
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// Range specifies the greatest expected change in amplitude. Calculate it
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// by finding the difference between the maximum and minimum expected
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// amplitudes (max - min).
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template<int quality,int range>
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class Blip_Synth {
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public:
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// Set overall volume of waveform
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void volume( double v ) { impl.volume_unit( v * (1.0 / (range < 0 ? -range : range)) ); }
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// Configure low-pass filter (see blip_buffer.txt)
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void treble_eq( blip_eq_t const& eq ) { impl.treble_eq( eq ); }
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// Get/set Blip_Buffer used for output
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Blip_Buffer* output() const { return impl.buf; }
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void output( Blip_Buffer* b ) { impl.buf = b; impl.last_amp = 0; }
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// Update amplitude of waveform at given time. Using this requires a separate
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// Blip_Synth for each waveform.
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void update( blip_time_t time, int amplitude );
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// Low-level interface
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// Add an amplitude transition of specified delta, optionally into specified buffer
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// rather than the one set with output(). Delta can be positive or negative.
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// The actual change in amplitude is delta * (volume / range)
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void offset( blip_time_t, int delta, Blip_Buffer* ) const;
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void offset( blip_time_t t, int delta ) const { offset( t, delta, impl.buf ); }
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// Works directly in terms of fractional output samples. Contact author for more info.
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void offset_resampled( blip_resampled_time_t, int delta, Blip_Buffer* ) const;
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// Same as offset(), except code is inlined for higher performance
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void offset_inline( blip_time_t t, int delta, Blip_Buffer* buf ) const {
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offset_resampled( t * buf->factor_ + buf->offset_, delta, buf );
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}
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void offset_inline( blip_time_t t, int delta ) const {
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offset_resampled( t * impl.buf->factor_ + impl.buf->offset_, delta, impl.buf );
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}
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private:
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#if BLIP_BUFFER_FAST
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Blip_Synth_Fast_ impl;
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#else
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Blip_Synth_ impl;
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typedef short imp_t;
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imp_t impulses [blip_res * (quality / 2) + 1];
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public:
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Blip_Synth() : impl( impulses, quality ) { }
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#endif
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};
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// Low-pass equalization parameters
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class blip_eq_t {
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public:
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// Logarithmic rolloff to treble dB at half sampling rate. Negative values reduce
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// treble, small positive values (0 to 5.0) increase treble.
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blip_eq_t( double treble_db = 0 );
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// See blip_buffer.txt
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blip_eq_t( double treble, long rolloff_freq, long sample_rate, long cutoff_freq = 0 );
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private:
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double treble;
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long rolloff_freq;
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long sample_rate;
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long cutoff_freq;
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void generate( float* out, int count ) const;
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friend class Blip_Synth_;
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};
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int const blip_sample_bits = 30;
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// Dummy Blip_Buffer to direct sound output to, for easy muting without
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// having to stop sound code.
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class Silent_Blip_Buffer : public Blip_Buffer {
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buf_t_ buf [blip_buffer_extra_ + 1];
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public:
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// The following cannot be used (an assertion will fail if attempted):
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blargg_err_t set_sample_rate( long samples_per_sec, int msec_length );
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blip_time_t count_clocks( long count ) const;
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void mix_samples( blip_sample_t const* buf, long count );
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Silent_Blip_Buffer();
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};
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#if defined (__GNUC__) || _MSC_VER >= 1100
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#define BLIP_RESTRICT __restrict
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#else
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#define BLIP_RESTRICT
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#endif
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// Optimized reading from Blip_Buffer, for use in custom sample output
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// Begin reading from buffer. Name should be unique to the current block.
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#define BLIP_READER_BEGIN( name, blip_buffer ) \
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const Blip_Buffer::buf_t_* BLIP_RESTRICT name##_reader_buf = (blip_buffer).buffer_;\
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blip_long name##_reader_accum = (blip_buffer).reader_accum_
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// Get value to pass to BLIP_READER_NEXT()
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#define BLIP_READER_BASS( blip_buffer ) ((blip_buffer).bass_shift_)
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// Constant value to use instead of BLIP_READER_BASS(), for slightly more optimal
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// code at the cost of having no bass control
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int const blip_reader_default_bass = 9;
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// Current sample
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#define BLIP_READER_READ( name ) (name##_reader_accum >> (blip_sample_bits - 16))
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// Current raw sample in full internal resolution
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#define BLIP_READER_READ_RAW( name ) (name##_reader_accum)
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// Advance to next sample
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#define BLIP_READER_NEXT( name, bass ) \
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(void) (name##_reader_accum += *name##_reader_buf++ - (name##_reader_accum >> (bass)))
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// End reading samples from buffer. The number of samples read must now be removed
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// using Blip_Buffer::remove_samples().
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#define BLIP_READER_END( name, blip_buffer ) \
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(void) ((blip_buffer).reader_accum_ = name##_reader_accum)
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// Compatibility with older version
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const long blip_unscaled = 65535;
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const int blip_low_quality = blip_med_quality;
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const int blip_best_quality = blip_high_quality;
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// Deprecated; use BLIP_READER macros as follows:
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// Blip_Reader r; r.begin( buf ); -> BLIP_READER_BEGIN( r, buf );
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// int bass = r.begin( buf ) -> BLIP_READER_BEGIN( r, buf ); int bass = BLIP_READER_BASS( buf );
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// r.read() -> BLIP_READER_READ( r )
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// r.read_raw() -> BLIP_READER_READ_RAW( r )
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// r.next( bass ) -> BLIP_READER_NEXT( r, bass )
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// r.next() -> BLIP_READER_NEXT( r, blip_reader_default_bass )
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// r.end( buf ) -> BLIP_READER_END( r, buf )
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class Blip_Reader {
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public:
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int begin( Blip_Buffer& );
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blip_long read() const { return accum >> (blip_sample_bits - 16); }
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blip_long read_raw() const { return accum; }
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void next( int bass_shift = 9 ) { accum += *buf++ - (accum >> bass_shift); }
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void end( Blip_Buffer& b ) { b.reader_accum_ = accum; }
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private:
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const Blip_Buffer::buf_t_* buf;
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blip_long accum;
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};
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// End of public interface
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#include <assert.h>
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template<int quality,int range>
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inline void Blip_Synth<quality,range>::offset_resampled( blip_resampled_time_t time,
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int delta, Blip_Buffer* blip_buf ) const
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{
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// Fails if time is beyond end of Blip_Buffer, due to a bug in caller code or the
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// need for a longer buffer as set by set_sample_rate().
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assert( (blip_long) (time >> BLIP_BUFFER_ACCURACY) < blip_buf->buffer_size_ );
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delta *= impl.delta_factor;
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blip_long* BLIP_RESTRICT buf = blip_buf->buffer_ + (time >> BLIP_BUFFER_ACCURACY);
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int phase = (int) (time >> (BLIP_BUFFER_ACCURACY - BLIP_PHASE_BITS) & (blip_res - 1));
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#if BLIP_BUFFER_FAST
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blip_long left = buf [0] + delta;
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// Kind of crappy, but doing shift after multiply results in overflow.
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// Alternate way of delaying multiply by delta_factor results in worse
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// sub-sample resolution.
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blip_long right = (delta >> BLIP_PHASE_BITS) * phase;
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left -= right;
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right += buf [1];
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buf [0] = left;
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buf [1] = right;
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#else
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int const fwd = (blip_widest_impulse_ - quality) / 2;
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int const rev = fwd + quality - 2;
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int const mid = quality / 2 - 1;
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imp_t const* BLIP_RESTRICT imp = impulses + blip_res - phase;
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#if defined (_M_IX86) || defined (_M_IA64) || defined (__i486__) || \
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defined (__x86_64__) || defined (__ia64__) || defined (__i386__)
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// straight forward implementation resulted in better code on GCC for x86
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#define ADD_IMP( out, in ) \
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buf [out] += (blip_long) imp [blip_res * (in)] * delta
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#define BLIP_FWD( i ) {\
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ADD_IMP( fwd + i, i );\
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ADD_IMP( fwd + 1 + i, i + 1 );\
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}
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#define BLIP_REV( r ) {\
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ADD_IMP( rev - r, r + 1 );\
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ADD_IMP( rev + 1 - r, r );\
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}
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BLIP_FWD( 0 )
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if ( quality > 8 ) BLIP_FWD( 2 )
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if ( quality > 12 ) BLIP_FWD( 4 )
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{
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ADD_IMP( fwd + mid - 1, mid - 1 );
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ADD_IMP( fwd + mid , mid );
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imp = impulses + phase;
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}
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if ( quality > 12 ) BLIP_REV( 6 )
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if ( quality > 8 ) BLIP_REV( 4 )
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BLIP_REV( 2 )
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ADD_IMP( rev , 1 );
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ADD_IMP( rev + 1, 0 );
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#else
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// for RISC processors, help compiler by reading ahead of writes
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#define BLIP_FWD( i ) {\
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blip_long t0 = i0 * delta + buf [fwd + i];\
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blip_long t1 = imp [blip_res * (i + 1)] * delta + buf [fwd + 1 + i];\
|
||
|
i0 = imp [blip_res * (i + 2)];\
|
||
|
buf [fwd + i] = t0;\
|
||
|
buf [fwd + 1 + i] = t1;\
|
||
|
}
|
||
|
#define BLIP_REV( r ) {\
|
||
|
blip_long t0 = i0 * delta + buf [rev - r];\
|
||
|
blip_long t1 = imp [blip_res * r] * delta + buf [rev + 1 - r];\
|
||
|
i0 = imp [blip_res * (r - 1)];\
|
||
|
buf [rev - r] = t0;\
|
||
|
buf [rev + 1 - r] = t1;\
|
||
|
}
|
||
|
|
||
|
blip_long i0 = *imp;
|
||
|
BLIP_FWD( 0 )
|
||
|
if ( quality > 8 ) BLIP_FWD( 2 )
|
||
|
if ( quality > 12 ) BLIP_FWD( 4 )
|
||
|
{
|
||
|
blip_long t0 = i0 * delta + buf [fwd + mid - 1];
|
||
|
blip_long t1 = imp [blip_res * mid] * delta + buf [fwd + mid ];
|
||
|
imp = impulses + phase;
|
||
|
i0 = imp [blip_res * mid];
|
||
|
buf [fwd + mid - 1] = t0;
|
||
|
buf [fwd + mid ] = t1;
|
||
|
}
|
||
|
if ( quality > 12 ) BLIP_REV( 6 )
|
||
|
if ( quality > 8 ) BLIP_REV( 4 )
|
||
|
BLIP_REV( 2 )
|
||
|
|
||
|
blip_long t0 = i0 * delta + buf [rev ];
|
||
|
blip_long t1 = *imp * delta + buf [rev + 1];
|
||
|
buf [rev ] = t0;
|
||
|
buf [rev + 1] = t1;
|
||
|
#endif
|
||
|
|
||
|
#endif
|
||
|
}
|
||
|
|
||
|
#undef BLIP_FWD
|
||
|
#undef BLIP_REV
|
||
|
|
||
|
template<int quality,int range>
|
||
|
#if BLIP_BUFFER_FAST
|
||
|
inline
|
||
|
#endif
|
||
|
void Blip_Synth<quality,range>::offset( blip_time_t t, int delta, Blip_Buffer* buf ) const
|
||
|
{
|
||
|
offset_resampled( t * buf->factor_ + buf->offset_, delta, buf );
|
||
|
}
|
||
|
|
||
|
template<int quality,int range>
|
||
|
#if BLIP_BUFFER_FAST
|
||
|
inline
|
||
|
#endif
|
||
|
void Blip_Synth<quality,range>::update( blip_time_t t, int amp )
|
||
|
{
|
||
|
int delta = amp - impl.last_amp;
|
||
|
impl.last_amp = amp;
|
||
|
offset_resampled( t * impl.buf->factor_ + impl.buf->offset_, delta, impl.buf );
|
||
|
}
|
||
|
|
||
|
inline blip_eq_t::blip_eq_t( double t ) :
|
||
|
treble( t ), rolloff_freq( 0 ), sample_rate( 44100 ), cutoff_freq( 0 ) { }
|
||
|
inline blip_eq_t::blip_eq_t( double t, long rf, long sr, long cf ) :
|
||
|
treble( t ), rolloff_freq( rf ), sample_rate( sr ), cutoff_freq( cf ) { }
|
||
|
|
||
|
inline int Blip_Buffer::length() const { return length_; }
|
||
|
inline long Blip_Buffer::samples_avail() const { return (long) (offset_ >> BLIP_BUFFER_ACCURACY); }
|
||
|
inline long Blip_Buffer::sample_rate() const { return sample_rate_; }
|
||
|
inline int Blip_Buffer::output_latency() const { return blip_widest_impulse_ / 2; }
|
||
|
inline long Blip_Buffer::clock_rate() const { return clock_rate_; }
|
||
|
inline void Blip_Buffer::clock_rate( long cps ) { factor_ = clock_rate_factor( clock_rate_ = cps ); }
|
||
|
|
||
|
inline int Blip_Reader::begin( Blip_Buffer& blip_buf )
|
||
|
{
|
||
|
buf = blip_buf.buffer_;
|
||
|
accum = blip_buf.reader_accum_;
|
||
|
return blip_buf.bass_shift_;
|
||
|
}
|
||
|
|
||
|
int const blip_max_length = 0;
|
||
|
int const blip_default_length = 250;
|
||
|
|
||
|
#endif
|