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clock.c File Reference

The system clock manager. More...

#include <const.h>
#include <arch/i386.h>
#include <kernel/floppy.h>
#include <kernel/task.h>
#include <kernel/clock.h>

Go to the source code of this file.

Functions
void	init_clock ()
	Initialize channel 0 of the 8253A timer.
void	stop_clock ()
	Reset the clock for rebooting.
void	delay (dword millisec)
	Delay some milliseconds Parameters: millisec  How many milliseconds you want to delay.
void	set_timeout (timeout_t *t, unsigned int millisec)
	Initialize a timeout variable. Parameters: t  The timeout variable. millisec  How many milliseconds have to elapse before the timeout occurs.
bool	is_timeout (timeout_t *t)
	Check if a timeout has been elapsed. Parameters: t  The timeout variable.
dword	sys_get_ticks ()
	Return the system ticks. Returns: The system ticks.
void	clock_thread ()
	This is a task that occurs at every clock tick.
Variables
volatile dword	ticks = 0
	System ticks.

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Detailed Description

The system clock manager.

Author:

Andrea Righi <drizzt@inwind.it>

Date:

Last update: 2003-08-23

Note:

Copyright (©) 2003 Andrea Righi

Definition in file clock.c.

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Function Documentation

void clock_thread (    )

This is a task that occurs at every clock tick. Into this routine you can put every periodical task. You can change the frequency of the ticks changing the value of the HZ definition. This thread is invoked at every clock tick by the dispatcher(). Definition at line 109 of file clock.c. { ticks++; floppy_thread(); }

void delay (  dword    millisec )

Delay some milliseconds Parameters: millisec  How many milliseconds you want to delay. Definition at line 51 of file clock.c. { dword count, elapsed; dword IF = GET_IF(); // Start timer // elapsed = 0; while (elapsed < millisec) { // Poll ticks in memory // count = ticks; // Auto-sleep // enable(); idle(); // Update elapsed time // elapsed += (ticks - count)*1000/HZ; } SET_IF(IF); }

void init_clock (    )

Initialize channel 0 of the 8253A timer. Definition at line 21 of file clock.c. { dword IF = GET_IF(); disable(); outportb(TIMER_MODE, SQUARE_WAVE); // set timer on outportb(TIMER0, TIMER_COUNT & 0xFF); // timer low byte outportb(TIMER0, TIMER_COUNT >> 8); // timer high byte SET_IF(IF); }

bool is_timeout (  timeout_t *    t )

Check if a timeout has been elapsed. Parameters: t  The timeout variable. Definition at line 87 of file clock.c. { // Check if a timeout has gone // uint32_t elapsed; elapsed = ticks - t->start_ticks; return( elapsed >= t->ticks_to_wait ); }

void set_timeout (  timeout_t *    t, unsigned int    millisec )

Initialize a timeout variable. Parameters: t  The timeout variable. millisec  How many milliseconds have to elapse before the timeout occurs. Definition at line 79 of file clock.c. { t->start_ticks = ticks; t->ticks_to_wait = millisec * HZ / 1000; }

void stop_clock (    )

Reset the clock for rebooting. Definition at line 35 of file clock.c. { dword IF = GET_IF(); disable(); outportb(TIMER_MODE, SQUARE_WAVE); // set timer on outportb(TIMER0, 0); // timer low byte outportb(TIMER0, 0); // timer high byte SET_IF(IF); }

dword sys_get_ticks (  void    )

Return the system ticks. Returns: The system ticks. Definition at line 97 of file clock.c. { return(ticks); }

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Variable Documentation

volatile dword ticks = 0

System ticks. Definition at line 18 of file clock.c.

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