Timer namespace. More...

Enumerations
enum	PORT : uint8_t { CHANNEL_O = 0x40, CHANNEL_1 = 0x41, CHANNEL_2 = 0x42, COMMAND = 0x43 }

enum	CHANNEL : uint8_t { TIMER0 = 0x00, TIMER1 = 0x40, TIMER2 = 0x80 }

enum	ACCESSMODE : uint8_t { LATCH = 0x00, LO_ONLY = 0x10, HI_ONLY = 0x20, HI_LO = 0x30 }

enum	OPMODE : uint8_t { COUNTDOWN = 0x0, ONESHOT = 0x2, RATE_GENERATOR = 0x4, SQUAREWAVE_GENERATOR = 0x6, SOFTWARE_STROBE = 0x8, HARDWARE_STROBE = 0xA, RATE_GENERATOR2 = 0xC, SQUAREWAVE_GENERATOR2 = 0xE }

enum	DECIMALMODE : uint8_t { BINARY = 0x0, BCD = 0x1 }

Functions
void	PIT_825x ()

Variables
uint64_t	timer_ticks

const uint32_t	BASE_FREQ = 1'193'182
	14.31818 MHz / 12 (due to hardware historical reason) More...

const uint16_t	TICKS_PER_SECOND = 1'000

Detailed Description

Timer namespace.

Programmable Interval Timer (PIT) 8253/8254 chip.

See also: https://wiki.osdev.org/Programmable_Interval_Timer, www.osdever.net/bkerndev/Docs/pit.htm

Mode/Command byte
| 07 | 06 | 05 | 04 | 03 | 02 | 01 |     00     |
| Channel |  Access |   Operating  | BCD/Binary |

Enumeration Type Documentation

◆ ACCESSMODE

enum TIMER::ACCESSMODE : uint8_t

Enumerator
LATCH	00(00)'0000 Latch count value
LO_ONLY	00(01)'0000 Low byte only
HI_ONLY	00(10)'0000 Low byte only
HI_LO	00(11)'0000 Low byte only

Definition at line 47 of file pit.cpp.

◆ CHANNEL

enum TIMER::CHANNEL : uint8_t

Enumerator
TIMER0	(00)00'0000 Channel 0
TIMER1	(01)00'0000 Channel 1
TIMER2	(10)00'0000 Channel 2

Definition at line 40 of file pit.cpp.

◆ DECIMALMODE

enum TIMER::DECIMALMODE : uint8_t

Enumerator
BINARY	0000'000(0) 16 bit binary
BCD	0000'000(1) 4 digit binary coded decimal

Definition at line 67 of file pit.cpp.

◆ OPMODE

enum TIMER::OPMODE : uint8_t

Enumerator
COUNTDOWN	0000'(000)0
ONESHOT	0000'(001)0
RATE_GENERATOR	0000'(010)0
SQUAREWAVE_GENERATOR	0000'(011)0
SOFTWARE_STROBE	0000'(100)0
HARDWARE_STROBE	0000'(101)0
RATE_GENERATOR2	0000'(110)0
SQUAREWAVE_GENERATOR2	0000'(111)0

Definition at line 55 of file pit.cpp.

◆ PORT

enum TIMER::PORT : uint8_t

Enumerator
CHANNEL_O	I/O port for channel 0 data port.
CHANNEL_1	I/O port for channel 1 data port.
CHANNEL_2	I/O port for channel 2 data port.
COMMAND	Mode/command register.

Definition at line 32 of file pit.cpp.

Function Documentation

◆ PIT_825x()

void TIMER::PIT_825x ( )

Definition at line 76 of file pit.cpp.

Variable Documentation

◆ BASE_FREQ

const uint32_t TIMER::BASE_FREQ = 1'193'182

14.31818 MHz / 12 (due to hardware historical reason)

Definition at line 73 of file pit.cpp.

◆ TICKS_PER_SECOND

const uint16_t TIMER::TICKS_PER_SECOND = 1'000

Definition at line 74 of file pit.cpp.

◆ timer_ticks

uint64_t TIMER::timer_ticks

Definition at line 30 of file pit.cpp.

Enumerations

Functions

Variables