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#include "timer.h"
#include "interrupts.h"
#include "kernel.h"
#include "log.h"
#include "asm_x86.h"
#include "asm_pit.h"
static volatile uint64_t task_system_clock_start=0;
// CMOS RTC
// read real time clock register
static unsigned char get_rtc_reg(int reg) {
x86_outb(0x70, reg); //cmos at addr 0x70
return x86_inb(0x71); //cmos data at addr 0x71
}
// check if cmos rtc update in progress
static int get_rtc_update_flag() {
x86_outb(0x70, 0x0A);
return (x86_inb(0x71) & 0x80);
}
// get real time clock rom cmos (seconds since jan)
static uint64_t get_rtc_time()
{
int CURRENT_YEAR = 2018; // Change this each year!
int century_register = 0x00; // Set by ACPI table parsing code if possible
unsigned char second;
unsigned char minute;
unsigned char hour;
unsigned char day;
unsigned char month;
unsigned int year;
unsigned char century;
unsigned char last_second;
unsigned char last_minute;
unsigned char last_hour;
unsigned char last_day;
unsigned char last_month;
unsigned char last_year;
unsigned char last_century;
unsigned char registerB;
// Note: This uses the "read registers until you get the same values twice in a row" technique
// to avoid getting dodgy/inconsistent values due to RTC updates
while (get_rtc_update_flag()); // Make sure an update isn't in progress
second = get_rtc_reg(0x00);
minute = get_rtc_reg(0x02);
hour = get_rtc_reg(0x04);
day = get_rtc_reg(0x07);
month = get_rtc_reg(0x08);
year = get_rtc_reg(0x09);
if(century_register != 0) {
century = get_rtc_reg(century_register);
}
do {
last_second = second;
last_minute = minute;
last_hour = hour;
last_day = day;
last_month = month;
last_year = year;
last_century = century;
while (get_rtc_update_flag()); // Make sure an update isn't in progress
second = get_rtc_reg(0x00);
minute = get_rtc_reg(0x02);
hour = get_rtc_reg(0x04);
day = get_rtc_reg(0x07);
month = get_rtc_reg(0x08);
year = get_rtc_reg(0x09);
if(century_register != 0) {
century = get_rtc_reg(century_register);
}
} while( (last_second != second) || (last_minute != minute) || (last_hour != hour) ||
(last_day != day) || (last_month != month) || (last_year != year) ||
(last_century != century) );
registerB = get_rtc_reg(0x0B);
// Convert BCD to binary values if necessary
if (!(registerB & 0x04)) {
second = (second & 0x0F) + ((second / 16) * 10);
minute = (minute & 0x0F) + ((minute / 16) * 10);
hour = ( (hour & 0x0F) + (((hour & 0x70) / 16) * 10) ) | (hour & 0x80);
day = (day & 0x0F) + ((day / 16) * 10);
month = (month & 0x0F) + ((month / 16) * 10);
year = (year & 0x0F) + ((year / 16) * 10);
if(century_register != 0) {
century = (century & 0x0F) + ((century / 16) * 10);
}
}
// Convert 12 hour clock to 24 hour clock if necessary
if (!(registerB & 0x02) && (hour & 0x80)) {
hour = ((hour & 0x7F) + 12) % 24;
}
// Calculate the full (4-digit) year
if(century_register != 0) {
year += century * 100;
} else {
year += (CURRENT_YEAR / 100) * 100;
if(year < CURRENT_YEAR) year += 100;
}
// thank you doug16k @ #osdev
// https://github.com/doug65536/dgos/blob/eab7080e69360493381669e7ce0ff27587d3127a/kernel/lib/time.cc
int days[] = {
31,
(year-1900) % 4 ? 28 :
(year-1900) % 100 ? 29 :
(year-1900) % 400 ? 28 :
29,
31,
30,
31,
30,
31,
31,
30,
31,
30,
31
};
int yday = 0;
for (int m = 1; m < month; ++m)
yday += days[m-1];
yday += day - 1;
uint64_t epoch_seconds= ((uint64_t)(second)) +
minute * 60 +
hour * 3600 +
(yday) * 86400 +
(year-1900 - 70) * 365 * 86400 +
((year-1900 - 69) / 4) * 86400 -
((year-1900 - 1) / 100) * 86400 +
((year-1900 + 299) / 400) * 86400;
return epoch_seconds;
}
uint32_t timer_interrupt(uint32_t esp)
{
asm_pit_tick();
return esp;
}
// PIT
uint64_t timer_init()
{
uint64_t epoch_time=get_rtc_time();
task_system_clock_start=epoch_time*25; // since pit ticks 25times a second
asm_pit_rate_40ms(); //tick at 25hz
fixme("pit rate does only seem to work occasionally.. 1/25 seconds???" );
interrupt_register(INTERRUPT_PIT_TIMER,&timer_interrupt);
return epoch_time;
}
uint64_t timer_get_ms()
{
return (asm_pit_get_ticks()+task_system_clock_start)*40;
}
uint64_t timer_get_uptime_ms()
{
return asm_pit_get_ticks()*40;
}
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