bw_phase_gen

Phase generator with portamento and exponential frequency modulation.

It outputs a normalized phase signal (range [0.f, 1.f)).

Examples

Here you can download one or more example VST3 plugins for Windows, macOS and Linux. Source code of the audio engine(s) is included in the archive(s).

VST® is a trademark of Steinberg Media Technologies GmbH, registered in Europe and other countries.

API

Module type: DSP

bw_phase_gen_coeffs

typedef struct bw_phase_gen_coeffs bw_phase_gen_coeffs;

Coefficients and related.

bw_phase_gen_state

typedef struct bw_phase_gen_state bw_phase_gen_state;

Internal state and related.

bw_phase_gen_init()

static inline void bw_phase_gen_init(
	bw_phase_gen_coeffs * BW_RESTRICT coeffs);

Initializes input parameter values in coeffs.

bw_phase_gen_set_sample_rate()

static inline void bw_phase_gen_set_sample_rate(
	bw_phase_gen_coeffs * BW_RESTRICT coeffs,
	float                             sample_rate);

Sets the sample_rate (Hz) value in coeffs.

bw_phase_gen_reset_coeffs()

static inline void bw_phase_gen_reset_coeffs(
	bw_phase_gen_coeffs * BW_RESTRICT coeffs);

Resets coefficients in coeffs to assume their target values.

bw_phase_gen_reset_state()

static inline void bw_phase_gen_reset_state(
	const bw_phase_gen_coeffs * BW_RESTRICT coeffs,
	bw_phase_gen_state * BW_RESTRICT        state,
	float                                   phase_0,
	float * BW_RESTRICT                     y_0,
	float * BW_RESTRICT                     y_inc_0);

Resets the given state to its initial values using the given coeffs and the initial phase value phase_0.

The corresponding initial output and phase increment values are put into y_0 and y_inc_0 respectively.

phase_0 must be in [0.f, 1.f).

bw_phase_gen_reset_state_multi()

static inline void bw_phase_gen_reset_state_multi(
	const bw_phase_gen_coeffs * BW_RESTRICT              coeffs,
	bw_phase_gen_state * BW_RESTRICT const * BW_RESTRICT state,
	const float *                                        phase_0,
	float *                                              y_0,
	float *                                              y_inc_0,
	size_t                                               n_channels);

Resets each of the n_channels states to its initial values using the given coeffs and the corresponding initial phase value in the phase_0 array.

The corresponding initial output and phase increment values are put into the y_0 and y_inc_0 arrays, respectively, if they are not BW_NULL.

Values in phase_0 must be in [0.f, 1.f).

bw_phase_gen_update_coeffs_ctrl()

static inline void bw_phase_gen_update_coeffs_ctrl(
	bw_phase_gen_coeffs * BW_RESTRICT coeffs);

Triggers control-rate update of coefficients in coeffs.

bw_phase_gen_update_coeffs_audio()

static inline void bw_phase_gen_update_coeffs_audio(
	bw_phase_gen_coeffs * BW_RESTRICT coeffs);

Triggers audio-rate update of coefficients in coeffs.

bw_phase_gen_process1*()

static inline void bw_phase_gen_process1(
	const bw_phase_gen_coeffs * BW_RESTRICT coeffs,
	bw_phase_gen_state * BW_RESTRICT        state,
	float * BW_RESTRICT                     y,
	float * BW_RESTRICT                     y_inc);

static inline void bw_phase_gen_process1_mod(
	const bw_phase_gen_coeffs * BW_RESTRICT coeffs,
	bw_phase_gen_state * BW_RESTRICT        state,
	float                                   x_mod,
	float * BW_RESTRICT                     y,
	float * BW_RESTRICT                     y_inc);

These functions generate one output sample using coeffs, while using and updating state, putting its value in y and the corresponding phase increment value in y_inc.

In particular:

• bw_phase_gen_process1() does not apply frequency modulation;
• bw_phase_gen_process1_mod() applies exponential frequency modulation using x_mod as modulation input (scale 1.f/octave).

bw_phase_gen_process()

static inline void bw_phase_gen_process(
	bw_phase_gen_coeffs * BW_RESTRICT coeffs,
	bw_phase_gen_state * BW_RESTRICT  state,
	const float *                     x_mod,
	float *                           y,
	float *                           y_inc,
	size_t                            n_samples);

Generates and fills the first n_samples of the output buffer y, while using and updating both coeffs and state (control and audio rate).

If x_mod is not BW_NULL, it is used as a source of exponential frequency modulation (scale 1.f/octave).

If y_inc is not BW_NULL, it is filled with phase increment values.

bw_phase_gen_process_multi()

static inline void bw_phase_gen_process_multi(
	bw_phase_gen_coeffs * BW_RESTRICT                    coeffs,
	bw_phase_gen_state * BW_RESTRICT const * BW_RESTRICT state,
	const float * const *                                x_mod,
	float * const *                                      y,
	float * const *                                      y_inc,
	size_t                                               n_channels,
	size_t                                               n_samples);

Generates and fills the first n_samples of the n_channels output buffers y, while using and updating both the common coeffs and each of the n_channels states (control and audio rate).

If x_mod and the channel-specific element are not BW_NULL, this is used as a source of exponential frequency modulation (scale 1.f/octave) for that channel.

If y_inc and the channel-specific element are not BW_NULL, this is filled with phase increment values for that channel.

bw_phase_gen_set_frequency()

static inline void bw_phase_gen_set_frequency(
	bw_phase_gen_coeffs * BW_RESTRICT coeffs,
	float                             value);

Sets the base frequency to value (Hz) in coeffs.

value must be finite.

Default value: 1.f.

bw_phase_gen_set_portamento_tau()

static inline void bw_phase_gen_set_portamento_tau(
	bw_phase_gen_coeffs * BW_RESTRICT coeffs,
	float                             value);

Sets the portamento time constant value (s) in coeffs.

value must be non-negative.

Default value: 0.f.

bw_phase_gen_set_phase_inc_min()

static inline void bw_phase_gen_set_phase_inc_min(
	bw_phase_gen_coeffs * BW_RESTRICT coeffs,
	float                             value);

Sets the minimum phase increment value in coeffs.

The algorithm will limit the actual phase increment accordingly, yet if the magnitude of the resulting phase increment is less than 6e-8f, it will be rounded to 0.f and such value will be reported by processing functions.

Valid range: [-INFINITY, INFINITY).

By the time bw_phase_gen_reset_\*(), bw_phase_gen_update_coeffs_\*(), or bw_peak_process\*() is called, phase_inc_min must be less than phase_inc_max.

Default value: -INFINITY.

bw_phase_gen_set_phase_inc_max()

static inline void bw_phase_gen_set_phase_inc_max(
	bw_phase_gen_coeffs * BW_RESTRICT coeffs,
	float                             value);

Sets the maximum phase increment value in coeffs.

The algorithm will limit the actual phase increment accordingly, yet if the magnitude of the resulting phase increment is less than 6e-8f, it will be rounded to 0.f and such value will be reported by processing functions.

Valid range: (-INFINITY, INFINITY].

By the time bw_phase_gen_reset_\*(), bw_phase_gen_update_coeffs_\*(), or bw_peak_process\*() is called, phase_inc_min must be less than phase_inc_max.

Default value: INFINITY.

bw_phase_gen_coeffs_is_valid()

static inline char bw_phase_gen_coeffs_is_valid(
	const bw_phase_gen_coeffs * BW_RESTRICT coeffs);

Tries to determine whether coeffs is valid and returns non-0 if it seems to be the case and 0 if it is certainly not. False positives are possible, false negatives are not.

coeffs must at least point to a readable memory block of size greater than or equal to that of bw_phase_gen_coeffs.

bw_phase_gen_state_is_valid()

static inline char bw_phase_gen_state_is_valid(
	const bw_phase_gen_coeffs * BW_RESTRICT coeffs,
	const bw_phase_gen_state * BW_RESTRICT  state);

Tries to determine whether state is valid and returns non-0 if it seems to be the case and 0 if it is certainly not. False positives are possible, false negatives are not.

If coeffs is not BW_NULL extra cross-checks might be performed (state is supposed to be associated to coeffs).

state must at least point to a readable memory block of size greater than or equal to that of bw_phase_gen_state.

C++ wrapper

Brickworks::PhaseGen

template<size_t N_CHANNELS>
class PhaseGen {
public:
	PhaseGen();

	void setSampleRate(
		float sampleRate);

	void reset(
		float               phase0 = 0.f,
		float * BW_RESTRICT y0 = nullptr,
		float * BW_RESTRICT yInc0 = nullptr);

# ifndef BW_CXX_NO_ARRAY
	void reset(
		float                                       phase0,
		std::array<float, N_CHANNELS> * BW_RESTRICT y0,
		std::array<float, N_CHANNELS> * BW_RESTRICT yInc0);
# endif

	void reset(
		const float * phase0,
		float *       y0 = nullptr,
		float *       yInc0 = nullptr);

# ifndef BW_CXX_NO_ARRAY
	void reset(
		std::array<float, N_CHANNELS>               phase0,
		std::array<float, N_CHANNELS> * BW_RESTRICT y0 = nullptr,
		std::array<float, N_CHANNELS> * BW_RESTRICT yInc0 = nullptr);
# endif

	void process(
		const float * const * xMod,
		float * const *       y,
		float * const *       yInc,
		size_t                nSamples);

# ifndef BW_CXX_NO_ARRAY
	void process(
		std::array<const float *, N_CHANNELS> xMod,
		std::array<float *, N_CHANNELS>       y,
		std::array<float *, N_CHANNELS>       yInc,
		size_t                                nSamples);
# endif

	void setFrequency(
		float value);

	void setPortamentoTau(
		float value);

	void setPhaseIncMin(
		float value);

	void setPhaseIncMax(
		float value);
...
}

Changelog

• Version 1.2.0:
  • Added phase_inc_min and phase_inc_max parameters.
  • Added support for BW_INCLUDE_WITH_QUOTES, BW_NO_CXX, and BW_CXX_NO_EXTERN_C.
  • Fixed rounding bug when frequency is tiny (again).
  • Added debugging checks from bw_phase_gen_process() to bw_phase_gen_process_multi().
  • Added debugging check in bw_phase_reset_state() to ensure that phase_0 is in [0.f, 1.f) and indicated such range in the documentation.
  • Added debugging checks in bw_phase_gen_process_multi() to ensure that buffers used for both input and output appear at the same channel indices.
  • Fixed bug in bw_phase_gen_process_multi() by which debugging code could report false negatives when BW_NULL buffers are used.
  • Fixed typo in the module description regarding output range.
• Version 1.1.0:
  • Fixed rounding bug when frequency is tiny and negative.
  • Now using BW_NULL and BW_CXX_NO_ARRAY.
• Version 1.0.0:
  • Added initial input value to bw_phase_gen_reset_state().
  • Added bw_phase_gen_reset_state_multi() and updated C++ API in this regard.
  • Now bw_phase_gen_reset_state() returns the initial output values.
  • Added overloaded C++ reset() functions taking arrays as arguments.
  • bw_phase_gen_process() and bw_phase_gen_process_multi() now use size_t to count samples and channels.
  • Added more const and BW_RESTRICT specifiers to input arguments and implementation.
  • Moved C++ code to C header.
  • Added overloaded C++ process() function taking C-style arrays as arguments.
  • Fixed smoothing coefficients update in bw_phase_gen_reset_coeffs().
  • Removed usage of reserved identifiers.
  • Clearly specified parameter validity ranges.
  • Added debugging code.
• Version 0.6.0:
  • Removed dependency on bw_config.
• Version 0.5.0:
  • Added bw_phase_gen_process_multi().
  • Added C++ wrapper.
• Version 0.4.0:
  • Fixed unused parameter warnings.
• Version 0.3.0:
  • Added BW_RESTRICT to bw_phase_gen_process1*().
• Version 0.2.0:
  • Refactored API.
• Version 0.1.0:
  • First release.