Timing functions. More...

#include <Library/UefiBootServicesTableLib.h>
#include <UEFIStarter/core/timestamp.h>
#include <UEFIStarter/core/logger.h>
#include <UEFIStarter/core/string.h>

Functions
int	init_timestamps ()
	Initializes the timestamp features. More...

UINT64	get_timestamp ()
	Fetches and returns the current timestamp. More...

double	timestamp_diff_seconds (UINT64 start, UINT64 end)
	Calculates the number of seconds between two timestamps. More...

UINT64	get_timestamp_ticks_per_second ()
	Returns the number of timestamp ticks per second. More...

Variables
UINT64	_rdtsc_ticks_per_second =0
	internal storage for the number of timestamp ticks per second

Detailed Description

Timing functions.

Author: Richard Nusser

Copyright: 2017-2018 Richard Nusser

License: GPLv3 (see http://www.gnu.org/licenses/)

See also: https://github.com/rinusser/UEFIStarter

Function Documentation

◆ init_timestamps()

int init_timestamps ( )

Initializes the timestamp features.

This will take ~2 seconds at current settings. This function takes the naive approach and simply measures how many ticks pass in 2 seconds. This tick frequency will be used later when converting ticks to seconds.

Make sure to call this function before you attempt to determine elapsed wallclock time.

Returns: 0 on success, an error code otherwise.

◆ get_timestamp()

UINT64 get_timestamp ( )

Fetches and returns the current timestamp.

Returns: the current timestamp

Todo:: this could be made inline for improved timing accuracy

◆ timestamp_diff_seconds()

double timestamp_diff_seconds	(	UINT64	start,
		UINT64	end
	)

Calculates the number of seconds between two timestamps.

This will only work if init_timestamps() has been called first.

Parameters

start	the start of the timestamp interval
end	the end of the timestamp interval

Returns: the difference in seconds

Todo:: this doesn't check for division by 0 errors on purpose, maybe check performance hit and add it if insignificant

◆ get_timestamp_ticks_per_second()

UINT64 get_timestamp_ticks_per_second ( )

Returns the number of timestamp ticks per second.

Returns: timestamp ticks per second