272 lines
6.6 KiB
C
272 lines
6.6 KiB
C
/*
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Copyright 2010,2011,2012,2013 Jun WAKO <wakojun@gmail.com>
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This software is licensed with a Modified BSD License.
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All of this is supposed to be Free Software, Open Source, DFSG-free,
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GPL-compatible, and OK to use in both free and proprietary applications.
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Additions and corrections to this file are welcome.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the
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distribution.
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* Neither the name of the copyright holders nor the names of
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* PS/2 protocol Pin interrupt version
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*/
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#include <stdbool.h>
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#include <avr/interrupt.h>
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#include <util/delay.h>
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#include "ps2.h"
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#include "ps2_io.h"
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#include "print.h"
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#define WAIT(stat, us, err) \
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do { \
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if (!wait_##stat(us)) { \
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ps2_error = err; \
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goto ERROR; \
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} \
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} while (0)
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uint8_t ps2_error = PS2_ERR_NONE;
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static inline uint8_t pbuf_dequeue(void);
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static inline void pbuf_enqueue(uint8_t data);
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static inline bool pbuf_has_data(void);
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static inline void pbuf_clear(void);
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void ps2_host_init(void) {
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idle();
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PS2_INT_INIT();
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PS2_INT_ON();
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// POR(150-2000ms) plus BAT(300-500ms) may take 2.5sec([3]p.20)
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//_delay_ms(2500);
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}
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uint8_t ps2_host_send(uint8_t data) {
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bool parity = true;
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ps2_error = PS2_ERR_NONE;
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PS2_INT_OFF();
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/* terminate a transmission if we have */
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inhibit();
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_delay_us(100); // 100us [4]p.13, [5]p.50
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/* 'Request to Send' and Start bit */
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data_lo();
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clock_hi();
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WAIT(clock_lo, 10000, 10); // 10ms [5]p.50
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/* Data bit[2-9] */
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for (uint8_t i = 0; i < 8; i++) {
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_delay_us(15);
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if (data & (1 << i)) {
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parity = !parity;
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data_hi();
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} else {
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data_lo();
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}
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WAIT(clock_hi, 50, 2);
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WAIT(clock_lo, 50, 3);
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}
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/* Parity bit */
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_delay_us(15);
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if (parity) {
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data_hi();
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} else {
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data_lo();
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}
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WAIT(clock_hi, 50, 4);
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WAIT(clock_lo, 50, 5);
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/* Stop bit */
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_delay_us(15);
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data_hi();
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/* Ack */
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WAIT(data_lo, 50, 6);
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WAIT(clock_lo, 50, 7);
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/* wait for idle state */
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WAIT(clock_hi, 50, 8);
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WAIT(data_hi, 50, 9);
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idle();
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PS2_INT_ON();
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return ps2_host_recv_response();
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ERROR:
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idle();
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PS2_INT_ON();
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return 0;
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}
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uint8_t ps2_host_recv_response(void) {
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// Command may take 25ms/20ms at most([5]p.46, [3]p.21)
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uint8_t retry = 25;
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while (retry-- && !pbuf_has_data()) {
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_delay_ms(1);
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}
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return pbuf_dequeue();
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}
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/* get data received by interrupt */
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uint8_t ps2_host_recv(void) {
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if (pbuf_has_data()) {
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ps2_error = PS2_ERR_NONE;
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return pbuf_dequeue();
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} else {
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ps2_error = PS2_ERR_NODATA;
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return 0;
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}
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}
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ISR(PS2_INT_VECT) {
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static enum {
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INIT,
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START,
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BIT0,
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BIT1,
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BIT2,
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BIT3,
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BIT4,
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BIT5,
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BIT6,
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BIT7,
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PARITY,
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STOP,
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} state = INIT;
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static uint8_t data = 0;
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static uint8_t parity = 1;
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// TODO: abort if elapse 100us from previous interrupt
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// return unless falling edge
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if (clock_in()) {
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goto RETURN;
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}
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state++;
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switch (state) {
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case START:
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if (data_in()) goto ERROR;
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break;
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case BIT0:
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case BIT1:
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case BIT2:
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case BIT3:
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case BIT4:
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case BIT5:
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case BIT6:
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case BIT7:
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data >>= 1;
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if (data_in()) {
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data |= 0x80;
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parity++;
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}
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break;
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case PARITY:
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if (data_in()) {
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if (!(parity & 0x01)) goto ERROR;
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} else {
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if (parity & 0x01) goto ERROR;
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}
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break;
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case STOP:
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if (!data_in()) goto ERROR;
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pbuf_enqueue(data);
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goto DONE;
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break;
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default:
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goto ERROR;
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}
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goto RETURN;
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ERROR:
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ps2_error = state;
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DONE:
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state = INIT;
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data = 0;
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parity = 1;
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RETURN:
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return;
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}
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/* send LED state to keyboard */
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void ps2_host_set_led(uint8_t led) {
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ps2_host_send(0xED);
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ps2_host_send(led);
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}
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/*--------------------------------------------------------------------
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* Ring buffer to store scan codes from keyboard
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*------------------------------------------------------------------*/
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#define PBUF_SIZE 32
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static uint8_t pbuf[PBUF_SIZE];
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static uint8_t pbuf_head = 0;
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static uint8_t pbuf_tail = 0;
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static inline void pbuf_enqueue(uint8_t data) {
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uint8_t sreg = SREG;
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cli();
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uint8_t next = (pbuf_head + 1) % PBUF_SIZE;
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if (next != pbuf_tail) {
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pbuf[pbuf_head] = data;
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pbuf_head = next;
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} else {
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print("pbuf: full\n");
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}
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SREG = sreg;
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}
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static inline uint8_t pbuf_dequeue(void) {
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uint8_t val = 0;
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uint8_t sreg = SREG;
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cli();
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if (pbuf_head != pbuf_tail) {
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val = pbuf[pbuf_tail];
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pbuf_tail = (pbuf_tail + 1) % PBUF_SIZE;
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}
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SREG = sreg;
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return val;
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}
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static inline bool pbuf_has_data(void) {
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uint8_t sreg = SREG;
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cli();
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bool has_data = (pbuf_head != pbuf_tail);
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SREG = sreg;
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return has_data;
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}
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static inline void pbuf_clear(void) {
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uint8_t sreg = SREG;
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cli();
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pbuf_head = pbuf_tail = 0;
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SREG = sreg;
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}
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