hos/src/hulk/pit.d

47 lines
1.3 KiB
D

/**
* PIT (Programmable Interval Timer) functionality.
*/
module hulk.pit;
import hulk.cpu;
import hulk.klog;
import hulk.console;
struct Pit
{
/** PIT input frequency in 1/1000 Hz. */
private enum ulong PIT_FREQUENCY_1000HZ = 1_193_181_667u;
private enum ulong TARGET_INTERRUPT_HZ = 1000u;
private enum ulong TARGET_INTERRUPT_1000HZ = TARGET_INTERRUPT_HZ * 1000u;
private enum ulong PIT_DIVIDER = (PIT_FREQUENCY_1000HZ + TARGET_INTERRUPT_1000HZ / 2u) / TARGET_INTERRUPT_1000HZ;
/** PIT channel 0 I/O port. */
private enum ubyte PORT_CH_0 = 0x40u;
/** PIT channel 1 I/O port. */
private enum ubyte PORT_CH_1 = 0x41u;
/** PIT channel 2 I/O port. */
private enum ubyte PORT_CH_2 = 0x42u;
/** PIT mode/command register I/O port. */
private enum ubyte PORT_MC = 0x43u;
private enum ubyte MC_CH_0 = 0x00u;
private enum ubyte MC_LO_HI = 0x30u;
private enum ubyte MC_RATE_GENERATOR = 0x04u;
private enum ubyte MC_BINARY = 0x00u;
private static __gshared ulong milliseconds;
public static void initialize()
{
Klog.writefln("\a3Initializing PIT");
out8(PORT_MC, MC_CH_0 | MC_LO_HI | MC_RATE_GENERATOR | MC_BINARY);
out8(PORT_CH_0, PIT_DIVIDER & 0xFFu);
out8(PORT_CH_0, PIT_DIVIDER >> 8u);
}
public static void isr()
{
milliseconds++;
}
}