timestamp.h File Reference

Timing functions. More...

#include <Uefi.h>

Go to the source code of this file.

Functions
double	timestamp_diff_seconds (UINT64 start, UINT64 end)
	Calculates the number of seconds between two timestamps. More...
int	init_timestamps ()
	Initializes the timestamp features. More...
UINT64	get_timestamp ()
	Fetches and returns the current timestamp. More...
UINT64	get_timestamp_ticks_per_second ()
	Returns the number of timestamp ticks per second. More...

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

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

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

get_timestamp_ticks_per_second()

UINT64 get_timestamp_ticks_per_second

(

)

Returns the number of timestamp ticks per second.

Returns

timestamp ticks per second