timer

Functions
int	timer_set_square (unsigned long timer, unsigned long freq)
	Configures a timer to generate a square wave.
int	timer_subscribe_int (void)
	Subscribes and enables Timer 0 interrupts.
int	timer_unsubscribe_int ()
	Unsubscribes Timer 0 interrupts.
void	timer_int_handler ()
	Timer 0 interrupt handler.
int	timer_test_square (unsigned long freq)
	Tests programming timer in square wave mode.
int	timer_test_int (unsigned long time)
	Tests Timer 0 interrupt handling.

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Detailed Description

Functions for using the i8254 timers

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Function Documentation

int timer_set_square	(	unsigned long	timer,
		unsigned long	freq
	)

Configures a timer to generate a square wave.

Parameters:

timer	Timer to configure. (Ranges from 0 to 2)
freq	Frequency of the square wave to generate

Returns:

Return 0 upon success and non-zero otherwise

int timer_subscribe_int

(

void

)

Subscribes and enables Timer 0 interrupts.

Returns:

Returns bit order in interrupt mask; negative value on failure

int timer_unsubscribe_int

(

)

Unsubscribes Timer 0 interrupts.

Returns:

Return 0 upon success and non-zero otherwise

void timer_int_handler

(

)

Timer 0 interrupt handler.

Increments counter

int timer_test_square

(

unsigned long

freq

)

Tests programming timer in square wave mode.

Programs Timer 0 to generate square mode with input frequency

Parameters:

freq	Frequency of square wave to generate

Returns:

Return 0 upon success and non-zero otherwise

int timer_test_int

(

unsigned long

time

)

Tests Timer 0 interrupt handling.

Subscribes Timer 0 interrupts and prints a message once per second for the specified time interval

Parameters:

time	Length of time interval while interrupts are subscribed

Returns:

Return 0 upon success and non-zero otherwise