X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=common%2Fserial.c;h=6bf730c8c7a4640fbac5f4730a79f578b2da3da8;hb=HEAD;hp=2bf6901836064ece4517047dcb8d94f70838d99f;hpb=9c37d18b9c70fdb70dfec453398c4649e9e57586;p=model-railway-devices.git

diff --git a/common/serial.c b/common/serial.c
index 2bf6901..6bf730c 100644
--- a/common/serial.c
+++ b/common/serial.c
@@ -1,22 +1,120 @@
+#include <avr/interrupt.h>
 #include <avr/io.h>
+#include "delay.h"
+#include "ringbuffer.h"
 #include "serial.h"
 
 #define BIT(n) (1<<(n))
 
+#ifndef SERIAL_BUFSIZE
+#define SERIAL_BUFSIZE 16
+#endif
+
+#ifdef SERIAL_ASYNC
+static RINGBUFFER(rx, SERIAL_BUFSIZE);
+static RINGBUFFER(tx, SERIAL_BUFSIZE);
+static uint8_t rx_overrun;
+#define INTERRUPTS BIT(RXCIE0)
+#else
+#define INTERRUPTS 0
+#endif
+
+static inline void set_baud(uint16_t baud)
+{
+	baud = (F_CPU/16+baud/2)/baud-1;
+	UBRR0H = baud>>8;
+	UBRR0L = baud;
+}
+
 void serial_init(uint16_t baud)
 {
 	DDRD = (DDRD&~0x03) | 0x02;
 	PORTD &= ~0x03;
 
-	baud = (F_CPU/16+baud/2)/baud-1;
-	UBRR0H = baud>>8;
-	UBRR0L = baud;
+	set_baud(baud);
+	UCSR0A = 0;
 	UCSR0C = BIT(UCSZ00) | BIT(UCSZ01);  // 8N1
-	UCSR0B = BIT(RXEN0) | BIT(TXEN0) | BIT(RXCIE0);
+	UCSR0B = BIT(RXEN0) | BIT(TXEN0) | INTERRUPTS;
+}
+
+void serial_set_baud(uint16_t baud)
+{
+#ifdef SERIAL_ASYNC
+	while(!(UCSR0A&BIT(UDRE0))) ;
+#endif
+	/* It's impossible to reliably find out when transmission has finished.
+	Wait for one character duration to be safe. */
+	uint16_t delay = (UBRR0H<<8)|UBRR0L;
+	for(uint8_t i=0; i<40; ++i)
+		delay_loop16(delay);
+	set_baud(baud);
+}
+
+uint8_t serial_read()
+{
+#ifdef SERIAL_ASYNC
+	return ringbuffer_blocking_pop(rx);
+#else
+	while(!(UCSR0A&BIT(RXC0))) ;
+	return UDR0;
+#endif
+}
+
+uint8_t serial_read_available()
+{
+#ifdef SERIAL_ASYNC
+	return ringbuffer_fill(rx);
+#else
+	return (UCSR0A&BIT(RXC0))!=0;
+#endif
+}
+
+uint8_t serial_read_overrun()
+{
+#ifdef SERIAL_ASYNC
+	uint8_t o = rx_overrun;
+	rx_overrun = 0;
+	return o;
+#else
+	return (UCSR0A&BIT(DOR0))!=0;
+#endif
 }
 
 void serial_write(uint8_t c)
 {
-	while(!(UCSR0A&(1<<UDRE0))) ;
+#ifdef SERIAL_ASYNC
+	ringbuffer_blocking_push(tx, c);
+	UCSR0B |= BIT(UDRIE0);
+#else
+	while(!(UCSR0A&BIT(UDRE0))) ;
 	UDR0 = c;
+#endif
+}
+
+uint8_t serial_write_space()
+{
+#ifdef SERIAL_ASYNC
+	return ringbuffer_space(tx);
+#else
+	return (UCSR0A&BIT(UDRE0))!=0;
+#endif
+}
+
+#ifdef SERIAL_ASYNC
+ISR(USART_UDRE_vect)
+{
+	if(ringbuffer_fill(tx))
+		UDR0 = ringbuffer_pop(tx);
+	else
+		UCSR0B &= ~BIT(UDRIE0);
+}
+
+ISR(USART_RX_vect)
+{
+	uint8_t c = UDR0;
+	if(!ringbuffer_space(rx))
+		rx_overrun = 1;
+	else
+		ringbuffer_push(rx, c);
 }
+#endif