Macros | Functions
pit8254.h File Reference

8254 Programmable Interval Timer More...

Go to the source code of this file.


#define PIT8254_CH_IRQ0   0
 IRQ0 channel. More...
#define PIT8254_CH_SPKR   2
 PC speaker channel. More...
#define PIT8254_HZ   1193182UL
 Timer frequency (1.193182MHz) More...
#define PIT8254_DATA(channel)   ( 0x40 + (channel) )
 Data port. More...
#define PIT8254_CMD   0x43
 Mode/command register. More...
#define PIT8254_CMD_CHANNEL(channel)   ( (channel) << 6 )
 Select channel. More...
#define PIT8254_CMD_ACCESS_LATCH   0x00
 Access modes. More...
#define PIT8254_CMD_ACCESS_LO   0x10
 Low byte only. More...
#define PIT8254_CMD_ACCESS_HI   0x20
 High byte only. More...
#define PIT8254_CMD_ACCESS_LOHI   0x30
 Low-byte, high-byte pair. More...
#define PIT8254_CMD_OP_TERMINAL   0x00
 Interrupt on terminal count. More...
#define PIT8254_CMD_OP_ONESHOT   0x02
 Hardware re-triggerable one-shot. More...
#define PIT8254_CMD_OP_RATE   0x04
 Rate generator. More...
#define PIT8254_CMD_OP_SQUARE   0x06
 Square wave generator. More...
#define PIT8254_CMD_OP_SWSTROBE   0x08
 Software triggered strobe. More...
#define PIT8254_CMD_OP_HWSTROBE   0x0a
 Hardware triggered strobe. More...
#define PIT8254_CMD_OP_RATE2   0x0c
 Rate generator (duplicate) More...
#define PIT8254_CMD_OP_SQUARE2   0x0e
 Square wave generator (duplicate) More...
#define PIT8254_CMD_BINARY   0x00
 Binary mode. More...
#define PIT8254_CMD_BCD   0x01
 BCD mode. More...
#define PIT8254_SPKR   0x61
 PC speaker control register. More...
#define PIT8254_SPKR_GATE   0x01
 PC speaker channel gate. More...
#define PIT8254_SPKR_ENABLE   0x02
 PC speaker enabled. More...
#define PIT8254_SPKR_OUT   0x20
 PC speaker channel output. More...


void pit8254_speaker_delay (unsigned int ticks)
 Delay for a fixed number of timer ticks using the speaker channel. More...
static __attribute__ ((always_inline)) void pit8254_udelay(unsigned long usecs)
 Delay for a fixed number of microseconds. More...

Detailed Description

8254 Programmable Interval Timer

Definition in file pit8254.h.

Macro Definition Documentation

◆ PIT8254_CH_IRQ0

#define PIT8254_CH_IRQ0   0

IRQ0 channel.

Definition at line 13 of file pit8254.h.


#define PIT8254_CH_SPKR   2

PC speaker channel.

Definition at line 16 of file pit8254.h.

◆ PIT8254_HZ

#define PIT8254_HZ   1193182UL

Timer frequency (1.193182MHz)

Definition at line 19 of file pit8254.h.

◆ PIT8254_DATA

#define PIT8254_DATA (   channel)    ( 0x40 + (channel) )

Data port.

Definition at line 22 of file pit8254.h.

◆ PIT8254_CMD

#define PIT8254_CMD   0x43

Mode/command register.

Definition at line 25 of file pit8254.h.


#define PIT8254_CMD_CHANNEL (   channel)    ( (channel) << 6 )

Select channel.

Definition at line 28 of file pit8254.h.


#define PIT8254_CMD_ACCESS_LATCH   0x00

Access modes.

Latch count value command

Definition at line 31 of file pit8254.h.


#define PIT8254_CMD_ACCESS_LO   0x10

Low byte only.

Definition at line 32 of file pit8254.h.


#define PIT8254_CMD_ACCESS_HI   0x20

High byte only.

Definition at line 33 of file pit8254.h.


#define PIT8254_CMD_ACCESS_LOHI   0x30

Low-byte, high-byte pair.

Definition at line 34 of file pit8254.h.


#define PIT8254_CMD_OP_TERMINAL   0x00

Interrupt on terminal count.

Definition at line 37 of file pit8254.h.


#define PIT8254_CMD_OP_ONESHOT   0x02

Hardware re-triggerable one-shot.

Definition at line 38 of file pit8254.h.


#define PIT8254_CMD_OP_RATE   0x04

Rate generator.

Definition at line 39 of file pit8254.h.


#define PIT8254_CMD_OP_SQUARE   0x06

Square wave generator.

Definition at line 40 of file pit8254.h.


#define PIT8254_CMD_OP_SWSTROBE   0x08

Software triggered strobe.

Definition at line 41 of file pit8254.h.


#define PIT8254_CMD_OP_HWSTROBE   0x0a

Hardware triggered strobe.

Definition at line 42 of file pit8254.h.


#define PIT8254_CMD_OP_RATE2   0x0c

Rate generator (duplicate)

Definition at line 43 of file pit8254.h.


#define PIT8254_CMD_OP_SQUARE2   0x0e

Square wave generator (duplicate)

Definition at line 44 of file pit8254.h.


#define PIT8254_CMD_BINARY   0x00

Binary mode.

Definition at line 47 of file pit8254.h.


#define PIT8254_CMD_BCD   0x01

BCD mode.

Definition at line 50 of file pit8254.h.

◆ PIT8254_SPKR

#define PIT8254_SPKR   0x61

PC speaker control register.

Definition at line 53 of file pit8254.h.


#define PIT8254_SPKR_GATE   0x01

PC speaker channel gate.

Definition at line 56 of file pit8254.h.


#define PIT8254_SPKR_ENABLE   0x02

PC speaker enabled.

Definition at line 59 of file pit8254.h.


#define PIT8254_SPKR_OUT   0x20

PC speaker channel output.

Definition at line 62 of file pit8254.h.

Function Documentation



◆ pit8254_speaker_delay()

void pit8254_speaker_delay ( unsigned int  ticks)

Delay for a fixed number of timer ticks using the speaker channel.

ticksNumber of timer ticks for which to delay

Definition at line 41 of file pit8254.c.

41  {
42  uint8_t spkr;
43  uint8_t cmd;
44  uint8_t low;
45  uint8_t high;
47  /* Sanity check */
48  assert ( ticks <= 0xffff );
50  /* Disable speaker, set speaker channel gate input high */
51  spkr = inb ( PIT8254_SPKR );
52  spkr &= ~PIT8254_SPKR_ENABLE;
53  spkr |= PIT8254_SPKR_GATE;
54  outb ( spkr, PIT8254_SPKR );
56  /* Program speaker channel to "interrupt" on terminal count */
60  low = ( ( ticks >> 0 ) & 0xff );
61  high = ( ( ticks >> 8 ) & 0xff );
62  outb ( cmd, PIT8254_CMD );
66  /* Wait for channel to "interrupt" */
67  do {
68  spkr = inb ( PIT8254_SPKR );
69  } while ( ! ( spkr & PIT8254_SPKR_OUT ) );
70 }
#define PIT8254_CMD_CHANNEL(channel)
Select channel.
Definition: pit8254.h:28
Low-byte, high-byte pair.
Definition: pit8254.h:34
#define PIT8254_SPKR_ENABLE
PC speaker enabled.
Definition: pit8254.h:59
#define PIT8254_CMD
Mode/command register.
Definition: pit8254.h:25
Interrupt on terminal count.
Definition: pit8254.h:37
#define PIT8254_SPKR_OUT
PC speaker channel output.
Definition: pit8254.h:62
#define PIT8254_SPKR
PC speaker control register.
Definition: pit8254.h:53
assert((readw(&hdr->flags) &(GTF_reading|GTF_writing))==0)
#define PIT8254_DATA(channel)
Data port.
Definition: pit8254.h:22
uint32_t low
Low 16 bits of address.
Definition: intel.h:21
#define PIT8254_CH_SPKR
PC speaker channel.
Definition: pit8254.h:16
#define PIT8254_CMD_BINARY
Binary mode.
Definition: pit8254.h:47
unsigned char uint8_t
Definition: stdint.h:10
uint8_t inb(volatile uint8_t *io_addr)
Read byte from I/O-mapped device.
#define outb(data, io_addr)
Definition: io.h:309
#define PIT8254_SPKR_GATE
PC speaker channel gate.
Definition: pit8254.h:56
uint32_t high
High 32 bits of address.
Definition: intel.h:22
struct golan_eqe_cmd cmd
Definition: CIB_PRM.h:29

References assert(), cmd, high, inb(), low, outb, PIT8254_CH_SPKR, PIT8254_CMD, PIT8254_CMD_ACCESS_LOHI, PIT8254_CMD_BINARY, PIT8254_CMD_CHANNEL, PIT8254_CMD_OP_TERMINAL, PIT8254_DATA, PIT8254_SPKR, PIT8254_SPKR_ENABLE, PIT8254_SPKR_GATE, and PIT8254_SPKR_OUT.

Referenced by __attribute__().

◆ __attribute__()

static __attribute__ ( (always_inline)  )

Delay for a fixed number of microseconds.

usecsNumber of microseconds for which to delay

Definition at line 71 of file pit8254.h.

72  {
74  /* Delays are invariably compile-time constants; force the
75  * multiplication and division to take place at compilation
76  * time rather than runtime.
77  */
78  pit8254_speaker_delay ( ( usecs * PIT8254_HZ ) / 1000000 );
79 }
#define PIT8254_HZ
Timer frequency (1.193182MHz)
Definition: pit8254.h:19
void pit8254_speaker_delay(unsigned int ticks)
Delay for a fixed number of timer ticks using the speaker channel.
Definition: pit8254.c:41

References PIT8254_HZ, and pit8254_speaker_delay().