megax4/uart: implement u2x (double uart transmission speed)

diff --git a/simavr/cores/sim_megax4.h b/simavr/cores/sim_megax4.h
index 4b6c463..5ff74fe 100644 (file)
--- a/simavr/cores/sim_megax4.h
+++ b/simavr/cores/sim_megax4.h
@@ -119,6 +119,7 @@ const struct mcu_t SIM_CORENAME = {
                .name = '0',
                .r_udr = UDR0,
 
+               .u2x = AVR_IO_REGBIT(UCSR0A, U2X0),
                .txen = AVR_IO_REGBIT(UCSR0B, TXEN0),
                .rxen = AVR_IO_REGBIT(UCSR0B, RXEN0),
                .ucsz = AVR_IO_REGBITS(UCSR0C, UCSZ00, 0x3), // 2 bits
@@ -150,6 +151,7 @@ const struct mcu_t SIM_CORENAME = {
                .name = '1',
                .r_udr = UDR1,
 
+               .u2x = AVR_IO_REGBIT(UCSR1A, U2X1),
                .txen = AVR_IO_REGBIT(UCSR1B, TXEN1),
                .rxen = AVR_IO_REGBIT(UCSR1B, RXEN1),
                .ucsz = AVR_IO_REGBITS(UCSR1C, UCSZ10, 0x3), // 2 bits

diff --git a/simavr/sim/avr_uart.c b/simavr/sim/avr_uart.c
index 9911787..c42edaf 100644 (file)
--- a/simavr/sim/avr_uart.c
+++ b/simavr/sim/avr_uart.c
@@ -192,9 +192,8 @@ static void avr_uart_write(struct avr_t * avr, avr_io_addr_t addr, uint8_t v, vo
                //uint8_t udre = avr_regbit_get(avr, p->udrc.raised);
                uint8_t txc = avr_regbit_get(avr, p->txc.raised);
 
-               // no need to write this value in here, only the
-               // interrupt flags need clearing!
-               // avr_core_watch_write(avr, addr, v);
+                // required for u2x (double uart transmission speed)
+               avr_core_watch_write(avr, addr, v);
 
                //avr_clear_interrupt_if(avr, &p->udrc, udre);
                avr_clear_interrupt_if(avr, &p->txc, txc);