L4::Poll_timeout_counter Class Reference

Evaluate an expression for a maximum number of times. More...

#include <poll_timeout_counter.h>

Collaboration diagram for L4::Poll_timeout_counter:

Public Member Functions
	Poll_timeout_counter (unsigned counter_val)
	Constructor.
void	set (unsigned counter_val)
	Set the counter to a certain value.
bool	test (bool expression=true)
	Evaluate the expression for a maximum number of times.
bool	timed_out () const
	Indicator if the maximum number of tests was required.

Detailed Description

Evaluate an expression for a maximum number of times.

A typical use case is testing for a bit change in a hardware register for a maximum number of times (polling). For example:

Mmio_register_block regs;
Poll_timeout_counter i(3000000);
while (i.test(!(regs.read<l4_uint32_t>(0x04) & 1)))
  ;

The following usage is wrong:

...
Poll_timeout_counter i(3000000);
while (!i.test((regs.read<l4_uint32_t>(0x04) & 1)))
  ;

This loop would never terminate if the hardware register doesn't change!

Definition at line 34 of file poll_timeout_counter.h.

Constructor & Destructor Documentation

Poll_timeout_counter()

L4::Poll_timeout_counter::Poll_timeout_counter ( unsigned counter_val )

inline

Constructor.

Parameters

counter_val

Maximum number of times to repeat the test.

Definition at line 42 of file poll_timeout_counter.h.

References set().

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Member Function Documentation

set()

void L4::Poll_timeout_counter::set ( unsigned counter_val )

inline

Set the counter to a certain value.

Parameters

counter_val

New counter value for maximum number of times to repeat the test.

Definition at line 53 of file poll_timeout_counter.h.

Referenced by Poll_timeout_counter().

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timed_out()

bool L4::Poll_timeout_counter::timed_out ( ) const

inline

Indicator if the maximum number of tests was required.

Return values

true,if

the maximum number of tests was required or if the counter was initialized to zero.

Definition at line 81 of file poll_timeout_counter.h.

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The documentation for this class was generated from the following file:

• pkg/drivers-frst/include/poll_timeout_counter.h