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- /*
- Copyright 2013 Jun WAKO <wakojun@gmail.com>
-
- This software is licensed with a Modified BSD License.
- All of this is supposed to be Free Software, Open Source, DFSG-free,
- GPL-compatible, and OK to use in both free and proprietary applications.
- Additions and corrections to this file are welcome.
-
-
- Redistribution and use in source and binary forms, with or without
- modification, are permitted provided that the following conditions are met:
-
- * Redistributions of source code must retain the above copyright
- notice, this list of conditions and the following disclaimer.
-
- * Redistributions in binary form must reproduce the above copyright
- notice, this list of conditions and the following disclaimer in
- the documentation and/or other materials provided with the
- distribution.
-
- * Neither the name of the copyright holders nor the names of
- contributors may be used to endorse or promote products derived
- from this software without specific prior written permission.
-
- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- POSSIBILITY OF SUCH DAMAGE.
- */
-
- #include <stdbool.h>
- #include <avr/io.h>
- #include <avr/interrupt.h>
- #include "serial.h"
-
- #ifndef SERIAL_UART_BAUD
- # define SERIAL_UART_BAUD 9600
- #endif
-
- #define SERIAL_UART_UBRR (F_CPU / (16UL * SERIAL_UART_BAUD) - 1)
- #define SERIAL_UART_TXD_READY (UCSR1A & _BV(UDRE1))
- #define SERIAL_UART_RXD_VECT USART1_RX_vect
-
- #ifndef SERIAL_UART_INIT_CUSTOM
- # define SERIAL_UART_INIT_CUSTOM \
- /* enable TX */ \
- UCSR1B = _BV(TXEN1); \
- /* 8-bit data */ \
- UCSR1C = _BV(UCSZ11) | _BV(UCSZ10);
- #endif
-
- #if defined(SERIAL_UART_RTS_LO) && defined(SERIAL_UART_RTS_HI)
- // Buffer state
- // Empty: RBUF_SPACE == RBUF_SIZE(head==tail)
- // Last 1 space: RBUF_SPACE == 2
- // Full: RBUF_SPACE == 1(last cell of rbuf be never used.)
- # define RBUF_SPACE() (rbuf_head < rbuf_tail ? (rbuf_tail - rbuf_head) : (RBUF_SIZE - rbuf_head + rbuf_tail))
- // allow to send
- # define rbuf_check_rts_lo() \
- do { \
- if (RBUF_SPACE() > 2) SERIAL_UART_RTS_LO(); \
- } while (0)
- // prohibit to send
- # define rbuf_check_rts_hi() \
- do { \
- if (RBUF_SPACE() <= 2) SERIAL_UART_RTS_HI(); \
- } while (0)
- #else
- # define rbuf_check_rts_lo()
- # define rbuf_check_rts_hi()
- #endif
-
- void serial_init(void) {
- do {
- // Set baud rate
- UBRR1L = SERIAL_UART_UBRR;
- UBRR1L = SERIAL_UART_UBRR >> 8;
- SERIAL_UART_INIT_CUSTOM;
- } while (0);
- }
-
- // RX ring buffer
- #define RBUF_SIZE 256
- static uint8_t rbuf[RBUF_SIZE];
- static uint8_t rbuf_head = 0;
- static uint8_t rbuf_tail = 0;
-
- uint8_t serial_recv(void) {
- uint8_t data = 0;
- if (rbuf_head == rbuf_tail) {
- return 0;
- }
-
- data = rbuf[rbuf_tail];
- rbuf_tail = (rbuf_tail + 1) % RBUF_SIZE;
- rbuf_check_rts_lo();
- return data;
- }
-
- int16_t serial_recv2(void) {
- uint8_t data = 0;
- if (rbuf_head == rbuf_tail) {
- return -1;
- }
-
- data = rbuf[rbuf_tail];
- rbuf_tail = (rbuf_tail + 1) % RBUF_SIZE;
- rbuf_check_rts_lo();
- return data;
- }
-
- void serial_send(uint8_t data) {
- while (!SERIAL_UART_TXD_READY)
- ;
- SERIAL_UART_DATA = data;
- }
-
- // USART RX complete interrupt
- ISR(SERIAL_UART_RXD_VECT) {
- uint8_t next = (rbuf_head + 1) % RBUF_SIZE;
- if (next != rbuf_tail) {
- rbuf[rbuf_head] = SERIAL_UART_DATA;
- rbuf_head = next;
- }
- rbuf_check_rts_hi();
- }
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