timer.cpp File Reference

#include <Arch/i686/timer.hpp>
#include <Arch/i686/isr.hpp>

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Macros
#define	MAX_CALLBACKS   8

Typedefs
typedef void(*	voidfunc_t) ()

Functions
void	timer_init (uint32_t freq)
void	sleep (uint32_t ms)
void	timer_register_callback (void(*func)())

Variables
volatile uint32_t	timer_tick

Detailed Description

Programmable Interrupt Timer driver functions.

Author

Keeton Feavel (keeto.nosp@m.nfea.nosp@m.vel@c.nosp@m.edar.nosp@m.ville.nosp@m..edu)

Version

0.3

Date

2019-11-15

Copyright

Copyright the Xyris Contributors (c) 2019

Definition in file timer.cpp.

Macro Definition Documentation

MAX_CALLBACKS

#define MAX_CALLBACKS   8

Definition at line 19 of file timer.cpp.

Typedef Documentation

voidfunc_t

typedef void(* voidfunc_t) ()

Definition at line 17 of file timer.cpp.

Function Documentation

sleep()

void sleep

(

uint32_t

ms

)

Sleeps for a certain length of time.

Parameters

ms	Sleep length in milliseconds

Definition at line 52 of file timer.cpp.

                        {
    uint32_t start = timer_tick;
    uint32_t final = start + ms;
    // Waste CPU cycles like a slob
    while (timer_tick < final);
    // Return now that we've waited long enough
    return;
}

timer_init()

void timer_init

(

uint32_t

freq

)

Initialize the CPU timer with the given frequency.

Sleep Timer Non-Busy Waiting Idea: Create a struct that contains the end time and the callback function pointer that should be called when timer_tick = end After each timer_tick we check our end time and call the function if we're equal.

Definition at line 31 of file timer.cpp.

                               {
    /* Install the function we just wrote */
    Interrupts::registerHandler(Interrupts::INTERRUPT_0, timer_callback);
    /* Get the PIT value: hardware clock at 1193180 Hz */
    uint32_t divisor = 1193180 / freq;
    uint8_t low  = (uint8_t)(divisor & 0xFF);
    uint8_t high = (uint8_t)((divisor >> 8) & 0xFF);
    /* Send the command */
    writeByte(TIMER_COMMAND_PORT, 0x36);
    writeByte(TIMER_DATA_PORT, low);
    writeByte(TIMER_DATA_PORT, high);
}

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timer_register_callback()

void timer_register_callback

(

void(*)()

func

)

Definition at line 61 of file timer.cpp.

                                             {
    if (_callback_count < MAX_CALLBACKS - 1) {
        _callbacks[_callback_count] = func;
        _callback_count++;
    }
}

Variable Documentation

timer_tick

volatile uint32_t timer_tick

Definition at line 15 of file timer.cpp.