167 lines
2.3 KiB
C
167 lines
2.3 KiB
C
#include "kbd.h"
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include <util/delay.h>
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#include <stdbool.h>
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#include <stdint.h>
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static volatile int8_t kbd_state = 0;
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static volatile uint8_t kbd_input = 0;
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static volatile uint8_t kbd_output = 0;
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static volatile uint8_t kbd_flags = 0;
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static volatile uint8_t ts = 10;
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static inline bool kbd_data() {
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return (PINC & (1 << 0));
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}
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static inline bool kbd_clock() {
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return (PINC & (1 << 1));
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}
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static inline void kbd_clock_down() {
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DDRC |= 0x02;
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PORTC &= ~0x02;
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}
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static inline void kbd_clock_in() {
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DDRC &= ~0x02;
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PORTC |= 0x02;
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}
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static inline void kbd_data_set(bool state) {
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if (state)
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PORTC |= 0x01;
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else
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PORTC &= ~0x01;
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}
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static inline void kbd_data_out() {
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DDRC |= 0x01;
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}
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static inline void kbd_data_in() {
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DDRC &= ~0x01;
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PORTC |= 0x01;
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}
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static inline void kbd_wait() {
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while (kbd_state) {}
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}
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ISR(PCINT1_vect) {
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if (kbd_clock())
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return;
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if (kbd_state < 0) {
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if (kbd_state >= -8) {
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kbd_data_set(kbd_output & _BV(-1-kbd_state));
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}
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else if (kbd_state == -9) {
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kbd_data_set(!(__builtin_popcount(kbd_output) & 1));
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}
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else if (kbd_state == -10) {
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kbd_data_in();
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}
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else {
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kbd_state = 0;
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return;
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}
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kbd_state--;
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return;
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}
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bool data = kbd_data();
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if (kbd_state == 0) {
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if (!data) { /* start bit */
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kbd_input = 0;
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kbd_state++;
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}
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return;
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}
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if (kbd_state <= 8) {
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if (data)
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kbd_input |= _BV(kbd_state-1);
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kbd_state++;
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return;
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}
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if (kbd_state == 9) {
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if ((__builtin_popcount(kbd_input) & 1) == data)
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kbd_flags |= KBD_FLAG_ERROR;
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kbd_state++;
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return;
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}
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kbd_state = 0;
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if (kbd_flags & KBD_FLAG_ERROR) {
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/* Retry */
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return;
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}
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if (kbd_input == 0xe0) {
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kbd_flags |= KBD_FLAG_EXT;
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return;
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}
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if (kbd_input == 0xf0) {
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kbd_flags |= KBD_FLAG_BREAK;
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return;
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}
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uint16_t code = kbd_input;
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if (kbd_flags & KBD_FLAG_EXT)
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code |= 0xe000;
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kbd_handle(code, !(kbd_flags & KBD_FLAG_BREAK));
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kbd_flags = 0;
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}
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void kbd_send(uint8_t command) {
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kbd_wait();
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kbd_clock_down();
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_delay_us(100);
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kbd_data_out();
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kbd_data_set(false);
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_delay_us(10);
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kbd_clock_in();
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kbd_output = command;
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kbd_state = -1;
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kbd_wait();
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/* wait for ack */
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while (!kbd_state) {}
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kbd_wait();
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}
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void kbd_init(void) {
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DDRC &= ~0x03;
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PORTC |= 0x03;
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PCMSK1 = (1 << PCINT9);
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PCICR = (1 << PCIE1);
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}
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