phase_iterator

Overview

Read phase first for prerequisite information.

440Hz Phase Increments phase_iterator is a class that iterates over the phase with an iteration step size specified by the given frequency and sampling rate. phase_iterator holds two phase members, the phase accumulator and the phase step size.

The phase accumulator, keeps track of the current phase value for the waveform. Initially, the accumulator is set to an arbitrary starting phase, usually 0. For each sample of the waveform, the phase step size value is added to the current phase accumulator, which inherently rewraps the value when the next phase exceeds 2π.

Include

#include <q/support/phase.hpp>

Declaration

struct phase_iterator
{
   constexpr                     phase_iterator();
   constexpr                     phase_iterator(frequency freq, float sps);

   constexpr phase_iterator      operator++(int);
   constexpr phase_iterator&     operator++();
   constexpr phase_iterator      operator--(int);
   constexpr phase_iterator&     operator--();

   constexpr phase_iterator&     operator=(phase rhs);
   constexpr phase_iterator&     operator=(phase_iterator const& rhs) = default;

   constexpr void                set(frequency freq, float sps);

   constexpr bool                first() const;
   constexpr bool                last() const;
   constexpr phase_iterator      begin() const;
   constexpr phase_iterator      end() const;
   constexpr phase_iterator      middle() const;

   phase                         _phase, _step;
};

Expressions

Notation

freq

Object of type frequency

sps

Floating point value representing samples per second

i, a, b

Objects of type phase_iterator

p

Objects of type phase

Constructors and Assignments

Expression Semantics

phase_iterator()

Default construct a phase_iterator.

phase_iterator(freq, sps)

Construct a phase_iterator from the freq and sps

phase_iterator(i)

Copy construct from phase_iterator i.

a = b

Assign phase_iterator b, to phase_iterator a.

i = p

Assign phase p, to phase_iterator i. See Modifying The State.
C++ brace initialization may also be used.

Iteration

Expression Semantics Return Type

i++

Post increment. Returns a copy of the iterator made prior to increment.

phase_iterator

++i

Pre increment. Increment and return a reference to the iterator.

phase_iterator&

i--

Post decrement. Returns a copy of the iterator made prior to decrement.

phase_iterator

--i

Pre decrement. Decrement and return a reference to the iterator.

phase_iterator&

Mutator

Expression Semantics Return Type

set(freq, sps)

Modify a phase_iterator given a new freq and sps. See Modifying The State.

void

Modifying The State

When modifying a phase_iterator with a new frequency, freq, and sampling rate, sps, only the phase step size will be changed. To prevent discontinuities, the phase accumulator will not be touched. This means that the phase accumulator will continue to count up from its previous value, while the updated phase step size will determine the new frequency.

Accessors

Expression Semantics Return Type

i.first()

Returns true if the phase_iterator is at the start of the waveform cycle (0° or 0 rad). I.e. the phase accumulator is within 0 to phase step size.

bool

i.last()

Returns true if the phase_iterator is at the end of the waveform cycle (360° or 2π rad). I.e. the phase accumulator is within phase step size below 2π.

bool

i.begin()

Return a new phase_iterator with the same frequency, but with the phase accumulator set at the start of the waveform cycle (0° or 0 rad).

phase_iterator

i.end()

Return a new phase_iterator with the same frequency, but with the phase accumulator set at the end of the waveform cycle (360° or 2π rad).

phase_iterator

i.middle()

Return a new phase_iterator with the same frequency, but with the phase accumulator set at the middle of the waveform cycle (180° or π rad)

phase_iterator

i._phase

Direct access to the phase accumulator.

phase&

i._step

Direct access to the phase step size.

phase&