/*
+ * (C) Copyright 2014 Leo C. <erbl259-lmu@yahoo.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
*/
#include <avr/io.h>
#include <errno.h>
#include <stdio.h>
+#include "ring.h"
#include "serial.h"
static int _write(char c, FILE *stream);
-static FILE mystdout = FDEV_SETUP_STREAM(_write,
+static FILE mystdout = FDEV_SETUP_STREAM(_write,
NULL, _FDEV_SETUP_WRITE);
-#define CTL_S ('S'-'@') /* DC3 (Stop) */
-#define CTL_Q ('Q'-'@') /* DC1 (Start) */
-typedef enum {
- IDLE,
- ACTIVE,
- REQ_STOP,
- REQ_CONT,
- STOPPED
-} xmit_stat_t;
-
-static volatile uint8_t stat_tx;
-static volatile uint8_t stat_rx;
-
-
-struct ring {
- uint8_t *data;
- uint_fast8_t mask;
- volatile uint_fast8_t begin;
- volatile uint_fast8_t end;
-};
-
-
-#define BUFFER_SIZE 256
+#define BUFFER_SIZE 128
#if ((BUFFER_SIZE-1) & BUFFER_SIZE)
# error: BUFFER_SIZE not power of 2
#endif
#if ((BUFFER_SIZE) > 256)
-# error: BUFFER_SIZE
+# error: BUFFER_SIZE
#endif
struct ring rx_ring;
uint8_t tx_ring_buffer[BUFFER_SIZE];
-static void ring_init(struct ring *ring, uint8_t *buf, int size)
-{
- ring->data = buf;
- ring->mask = (size-1) & 0xff;
- ring->begin = 0;
- ring->end = 0;
-}
-
-static int ring_write_ch(struct ring *ring, uint8_t ch)
-{
- uint_fast8_t ep = (ring->end + 1) & ring->mask;
-
- if ((ep) != ring->begin) {
- ring->data[ring->end] = ch;
- ring->end = ep;
- return 1;
- }
-
- return -1;
-}
-
-#if 0
-static int ring_write(struct ring *ring, uint8_t *data, int size)
-{
- int i;
-
- for (i = 0; i < size; i++) {
- if (ring_write_ch(ring, data[i]) < 0)
- return -i;
- }
-
- return i;
-}
-#endif
-
-static int ring_read_ch(struct ring *ring)
-{
- int ret = -1;
- uint_fast8_t i = ring->begin;
-
- if (i != ring->end) {
- ret = ring->data[i];
- ring->begin = (i +1) & ring->mask;
- }
-
- return ret;
-}
-
-
-static int_fast8_t ring_is_empty(struct ring *ring)
-{
- return ring->begin == ring->end;
-}
-
/* Initialize UART */
-void usart0_setup(void) {
+void usart0_setup(unsigned long baud) {
ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
ring_init(&rx_ring, rx_ring_buffer, BUFFER_SIZE);
ring_init(&tx_ring, tx_ring_buffer, BUFFER_SIZE);
- stat_tx = ACTIVE;
- stat_rx = ACTIVE;
-
- UCSR0A = _BV(U2X0);
- UBRR0L = F_CPU / BAUD / 8 - 1;
+ UCSR0A = 0;
+ UBRR0 = F_CPU / baud / 16 - 1;
UCSR0B = _BV(RXCIE0) | _BV(RXEN0) | _BV(TXEN0);
UCSR0C = 3 << UCSZ00;
};
}
-
+/*--------------------------------------------------------------------------*/
/* UART RXC interrupt */
uint8_t d;
d = UDR0;
-
- switch (d) {
- case CTL_S:
- stat_tx = REQ_STOP;
- break;
- case CTL_Q:
- if ((stat_tx == STOPPED) || stat_tx == REQ_STOP) {
- UCSR0B = _BV(RXCIE0) | _BV(RXEN0) | _BV(TXEN0) | _BV(UDRIE0);
- stat_tx = ACTIVE;
- }
- break;
- default:
- ring_write_ch(&rx_ring, d);
- break;
- }
+ ring_write_ch(&rx_ring, d);
}
/* UART UDRE interrupt */
ISR(USART0_UDRE_vect)
{
- uint8_t s;
+ int d = ring_read_ch(&tx_ring);
- s = !ring_is_empty(&tx_ring);
- if ((s == 0) || (stat_tx != ACTIVE)) {
+ if (d < 0) {
+ /* Disable TX empty interrupt. */
UCSR0B = _BV(RXCIE0) | _BV(RXEN0) | _BV(TXEN0);
- if (s)
- stat_tx = STOPPED;
} else {
- UDR0 = ring_read_ch(&tx_ring);
+ UDR0 = d;
}
}
-
-
/*--------------------------------------------------------------------------*/
-void serial_setup(void)
+void serial_setup(unsigned long baud)
{
stdout = &mystdout;
- usart0_setup();
+ usart0_setup(baud);
}
/*--------------------------------------------------------------------------*/
return ring_read_ch(&rx_ring);
}
-void serial_putc(uint8_t data)
+void serial_putc(char data)
{
while (ring_write_ch(&tx_ring, data) < 0)
;
- switch (stat_tx) {
- case ACTIVE:
- default:
- /* Enable the TXE interrupt. */
- UCSR0B = _BV(RXCIE0) | _BV(RXEN0) | _BV(TXEN0) | _BV(UDRIE0);
- break;
- }
+
+ /* Enable the TXE interrupt. */
+ UCSR0B = _BV(RXCIE0) | _BV(RXEN0) | _BV(TXEN0) | _BV(UDRIE0);
}
+uint_fast8_t serial_tstc(void)
+{
+ return !ring_is_empty(&rx_ring);
+}