upkie::cpp::utils Namespace Reference

Utility functions. More...

Classes
class	SynchronousClock
	Synchronous (blocking) clock. More...

Functions
int	clear_shared_memory (const std::string &name)
	Clear an existing shared-memory file. More...
std::string	datetime_now_string ()
	Generate a date-time string. More...
const std::string	get_log_path (const std::string &log_dir, const std::string &spine_name)
	Get path to a fresh log file. More...
const bool &	handle_interrupts ()
	Redirect interrupts to setting a global interrupt boolean. More...
double	low_pass_filter (double prev_output, double cutoff_period, double new_input, double dt)
	Low-pass filter as an inline function. More...
bool	divides (uint32_t number, uint32_t divisor)
	True if and only if divisor divides number.
std::string	random_string (unsigned length=16)
	Generate a random string. More...
void	configure_cpu (int cpu)
	Set the current thread to run on a given CPU core. More...
void	configure_scheduler (int priority)
	Configure the scheduler policy to round-robin for this thread. More...
bool	lock_memory ()
	Lock all memory to RAM so that the kernel doesn't page it to swap. More...

Detailed Description

Utility functions.

Function Documentation

clear_shared_memory()

int upkie::cpp::utils::clear_shared_memory

(

const std::string &

name

)

Clear an existing shared-memory file.

Parameters

[in]

name

Name of the shared-memory file to remove if it exists.

Returns

EXIT_SUCCESS if the file is cleared, EXIT_FAILURE otherwise.

configure_cpu()

void upkie::cpp::utils::configure_cpu ( int  cpu )

inline

Set the current thread to run on a given CPU core.

Parameters

cpu	CPU core for this thread (on the Pi, CPUID in {0, 1, 2, 3}).

Exceptions

std::runtime_error

If the operation failed.

configure_scheduler()

void upkie::cpp::utils::configure_scheduler ( int  priority )

inline

Configure the scheduler policy to round-robin for this thread.

Parameters

priority

Priority of this thread for the scheduler, ranging from 1 (low) to 99 (high). See man sched. For agents, this priority should be lower than that of the spine.

Exceptions

std::runtime_error

If the operation failed.

datetime_now_string()

std::string upkie::cpp::utils::datetime_now_string ( )

inline

Generate a date-time string.

Returns

Date-time string at the time the function is called.

Uses the same format as the Python utility function.

get_log_path()

const std::string upkie::cpp::utils::get_log_path ( const std::string &  log_dir, const std::string &  spine_name  )

inline

Get path to a fresh log file.

Parameters

[in]	log_dir	Path to the logging directory.
[in]	spine_name	Name of the spine.

Returns

Path to a fresh log file.

Uses the same format as the Python utility function.

handle_interrupts()

const bool & upkie::cpp::utils::handle_interrupts

(

)

Redirect interrupts to setting a global interrupt boolean.

Direct interrupts (e.g.

Returns

Reference to the interrupt boolean.

Ctrl-C) to a boolean flag.

Returns

Reference to a boolean flag, which is initially false and becomes true the first time an interruption is caught.

lock_memory()

bool upkie::cpp::utils::lock_memory ( )

inline

Lock all memory to RAM so that the kernel doesn't page it to swap.

The Linux man pages have a great NOTES section on this. Worth a read!

low_pass_filter()

double upkie::cpp::utils::low_pass_filter ( double  prev_output, double  cutoff_period, double  new_input, double  dt  )

inline

Low-pass filter as an inline function.

Parameters

prev_output	Previous filter output, or initial value.
cutoff_period	Cutoff period in [s].
new_input	New filter input.
dt	Sampling period in [s].

Returns

New filter output.

random_string()

std::string upkie::cpp::utils::random_string ( unsigned  length = 16 )

inline

Generate a random string.

Parameters

[in]

length

String length.

Returns

Random string.

The generated string contains only alphanumeric characters with no repetition.