luxos/SysCore/drivers/clock/pit.c

#include <system.h>
#include <time.h>
#include "clock.h"

volatile unsigned int ClockTicks = 0;
volatile unsigned int ClockFrequency = 0;
unsigned char PitInitialized = 0;
volatile TIME _InternalClock;


void PitSetFrequency(int frequency)
{
      int divisor = 1193180/frequency;           // Calculate the divisor
      outportb(0x43, 0x36);               // Set our command byte 0x36
      outportb(0x40, divisor&0xFF);       // Set low byte
      outportb(0x40, divisor>>8);         // Set high byte
      ClockFrequency = frequency;
}

void i86_PitHandler(ISR_stack_regs *r)
{
      ClockTicks++;                                  // count tick
      if (ClockTicks % ClockFrequency == 0)
                  _CLOCK_INC((TIME*)&_InternalClock);   // update internal clock
}

unsigned int ClockSetTickCount(unsigned int i)
{
      unsigned int r = ClockTicks;
      ClockTicks = i;
      return r;
}

unsigned int ClockGetTickCount()
{
      return ClockTicks;
}
unsigned int PitGetFrequency()
{
      return ClockFrequency;
}

void i86_PitInitialize(int freq)
{
      PitSetFrequency(freq);
      ClockTicks = 0;

      i86_GetRTC((TIME*) &_InternalClock);

      PitInitialized = 1;
}

TIME ClockGetTime()
{
    return _InternalClock;
}

unsigned char PitIsInitialized()
{
      return PitInitialized;
}


inline unsigned char CmosRead (unsigned char address)
{
      outportb(0x70, address); iowait();
      return inportb(0x71);
}

inline void CmosWrite (unsigned char address, unsigned char val)
{
      outportb(0x70, address); iowait();
      outportb(0x71, val);
}

void i86_SetRTC (const TIME* time)
{
      unsigned char BCD = ((CmosRead(0x0b)&4)==0) ? 1 : 0;
      unsigned char ampm = ((CmosRead(0x0b)&2)==0) ? 1 : 0;

      CmosWrite (0, (BCD) ? (time->second%10) | (time->second/10*16) : time->second);        // Seconds
      CmosWrite (2, (BCD) ? (time->minute%10) | (time->minute/10*16) : time->minute);        // Minutes

      if (ampm && time->hour > 12)                                                                // Hours
            CmosWrite (4, (BCD) ? (((time->hour - 12) % 10) | ((time->hour - 12)/10*16) | 0x80) : (time->hour | 0x80) );

      else if (ampm && time->hour == 0)                                                           // Midnight convention: 12 PM = 00:00
            CmosWrite (4, (BCD) ? 0x92 : 0x8C);

      else CmosWrite (4, (BCD) ? (time->hour%10) | (time->hour/10*16) : time->hour);         // 24h / AM

      CmosWrite (6, (BCD) ? (time->weekday%10) | (time->weekday/10*16) : time->weekday);     // Weekday
      CmosWrite (7, (BCD) ? (time->day%10) | (time->day/10*16) : time->day);                 // Day
      CmosWrite (8, (BCD) ? (time->month%10) | (time->month/10*16) : time->month);           // Month
      CmosWrite (9, (BCD) ? (time->year%10) | (time->year/10*16) : time->year);              // Year
      CmosWrite (0x32, (BCD) ? (time->century%10) | (time->century/10*16) : time->century);  // Century
}

void i86_GetRTC(TIME* tim)
{
      unsigned char BCD = ((CmosRead(0x0b)&4)==0) ? 1 : 0;
      unsigned char am_pm = ((CmosRead(0x0b)&2)==0) ? 1 : 0;

      tim->second = (BCD) ? (CmosRead(0x00)%16) + 10*(CmosRead(0x00)/16): CmosRead(0x00);
      tim->minute = (BCD) ? (CmosRead(0x02)%16) + 10*(CmosRead(0x02)/16): CmosRead(0x02);

      // Time is PM
      if (am_pm && CmosRead(0x04)&80) {
            tim->hour = (BCD) ? ((CmosRead(0x04)-0x80)%16) + 10*((CmosRead(0x04)-0x80)/16): CmosRead(0x04)-0x80;
            tim->hour += 12;
      }
      // 24Hour format, or AM
      else tim->hour = (BCD) ? (CmosRead(0x04)%16) + 10*(CmosRead(0x04)/16): CmosRead(0x04);

      tim->weekday = (BCD) ? (CmosRead(0x06)%16) + 10*(CmosRead(0x06)/16): CmosRead(0x06);
      tim->day = (BCD) ? (CmosRead(0x07)%16) + 10*(CmosRead(0x07)/16): CmosRead(0x07);
      tim->month = (BCD) ? (CmosRead(0x08)%16) + 10*(CmosRead(0x08)/16): CmosRead(0x08);
      tim->year = (BCD) ? (CmosRead(0x09)%16) + 10*(CmosRead(0x09)/16): CmosRead(0x09);
      tim->century = (BCD) ? (CmosRead(0x32)%16) + 10*(CmosRead(0x32)/16): CmosRead(0x32);
}