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/*
* src/uart.c
* (c) 2021 Jonas Gunz <himself@jonasgunz.de>
* License: All rights reserved.
*/
#include "uart.h"
struct ringbuff_s {
uint8_t buffer[256];
uint8_t read;
uint8_t write;
} rxc_buf, txc_buf ;
ISR(USART_RXC_vect) {
cli();
/* Discard if buffer full */
if( rxc_buf.read - 1 == rxc_buf.write )
goto end;
rxc_buf.buffer[rxc_buf.write] = UDR;
rxc_buf.write++;
end:
sei();
}
ISR(USART_UDRE_vect) {
cli();
/* Prevent interrupt loops */
if( txc_buf.read == txc_buf.write ) {
UCSRB &= ~(1<<UDRIE);
goto end;
}
UDR = txc_buf.buffer[txc_buf.read];
txc_buf.read++;
end:
sei();
}
void uart_init(){
memset( &txc_buf, 0, sizeof(txc_buf) );
memset( &rxc_buf, 0, sizeof(rxc_buf) );
UBRRH = (uint8_t)((UBRR)>>8);
UBRRL = (uint8_t)(UBRR);
UCSRB |= (1<<RXEN)|(1<<RXCIE)|(1<<TXEN);
}
uint8_t uart_putchar(char _c) {
if( txc_buf.read - 1 == txc_buf.write )
return 1;
txc_buf.buffer[txc_buf.write] = _c;
txc_buf.write ++;
UCSRB |= (1<<UDRIE);
return 0;
}
uint8_t uart_getchar(char *_c) {
if( rxc_buf.read == rxc_buf.write )
return 1;
*_c = rxc_buf.buffer[rxc_buf.read];
rxc_buf.read++;
return 0;
}
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