compatibility_feature.hpp File Reference

Maintain compatibility with Arduino API, etc. More...

#include <type_traits>

Go to the source code of this file.

Namespaces
namespace	m5
	Top level namespace of M5.

Functions
Arduino API
IRAM_ATTR unsigned long	m5::utility::millis ()
	Returns the number of milliseconds passed since the Arduino board began running the current program.
IRAM_ATTR unsigned long	m5::utility::micros ()
	Returns the number of microseconds since the Arduino board began running the current program.
void	m5::utility::delay (const unsigned long ms)
	Pauses the program for the amount of time (in milliseconds) specified as parameter.
void	m5::utility::delayMicroseconds (const unsigned int us)
	Pauses the program for the amount of time (in microseconds) specified by the parameter.

Elapsed time
using	m5::utility::elapsed_time_t = unsigned long
	Elapsed time unit (ms)
template<typename T >
T	m5::utility::elapsedSince (const T start_at, const T now)
	Gets the elapsed time between start_at and now.
elapsed_time_t	m5::utility::elapsedSince (const elapsed_time_t start_at)
	Gets the elapsed time since start_at.
template<typename T >
bool	m5::utility::hasElapsed (const T start_at, const typename std::common_type< T >::type duration, const T now)
	Has the duration passed between start_at and now?
bool	m5::utility::hasElapsed (const elapsed_time_t start_at, const elapsed_time_t duration)
	Has the duration passed since start_at?

Detailed Description

Maintain compatibility with Arduino API, etc.

Typedef Documentation

elapsed_time_t

using m5::utility::elapsed_time_t = unsigned long

Elapsed time unit (ms)

Note

Identical to the return type of millis(), so the elapsed time is computed at the width at which millis() itself wraps. Code driven by a clock of a different width should keep that width instead (see elapsedSince(const T, const T))

Function Documentation

delay()

void m5::utility::delay

(

const unsigned long

ms

)

Pauses the program for the amount of time (in milliseconds) specified as parameter.

Parameters

ms	delay time (ms)

Warning

Accuracy varies depending on the environment.

delayMicroseconds()

void m5::utility::delayMicroseconds

(

const unsigned int

us

)

Pauses the program for the amount of time (in microseconds) specified by the parameter.

Parameters

us	delay time (us)

Warning

Accuracy varies depending on the environment.

elapsedSince() [1/2]

elapsed_time_t m5::utility::elapsedSince ( const elapsed_time_t start_at )

inline

Gets the elapsed time since start_at.

Parameters

start_at

Time obtained by millis()

Returns

Elapsed time (ms)

elapsedSince() [2/2]

template<typename T >

T m5::utility::elapsedSince ( const T start_at, const T now )

inline

Gets the elapsed time between start_at and now.

Parameters

start_at	Earlier time
now	Current time

Returns

Elapsed time (ms)

Note

Unsigned subtraction yields the correct elapsed time even across the wrap of the clock

Overload for code that takes its current time from somewhere other than millis(), such as an injected clock that unit tests can drive

Warning

The subtraction happens in the caller's own type T, because modular arithmetic is only correct when its width matches the width at which the clock wraps. Widening a 32-bit clock to a 64-bit type before subtracting breaks the wrap, so T is deduced rather than fixed to elapsed_time_t

hasElapsed() [1/2]

bool m5::utility::hasElapsed ( const elapsed_time_t start_at, const elapsed_time_t duration )

inline

Has the duration passed since start_at?

Parameters

start_at	Time obtained by millis()
duration	Duration to wait for (ms)

Returns

True if the duration has passed

hasElapsed() [2/2]

template<typename T >

bool m5::utility::hasElapsed ( const T start_at, const typename std::common_type< T >::type duration, const T now )

inline

Has the duration passed between start_at and now?

Parameters

start_at	Earlier time
duration	Duration to wait for (ms)
now	Current time

Returns

True if the duration has passed

Note

Compares the elapsed time rather than a precomputed deadline. A deadline such as (start_at + duration) overflows near the wrap of the clock and cuts the wait short, so compare the elapsed time instead

Overload for code that takes its current time from somewhere other than millis(), such as an injected clock that unit tests can drive. The current time is the trailing argument so that the shorter form is a prefix of this one and cannot be called by mistake

Warning

The elapsed time is computed in the caller's own type T; see elapsedSince(const T, const T). duration is not deduced, so an integer literal may be passed without making the deduction ambiguous