From 5b1830d85cd06020f50290b5e5b8e9e5e7049dae Mon Sep 17 00:00:00 2001
From: Michel Pollet <buserror@gmail.com>
Date: Tue, 15 Mar 2011 13:33:54 +0000
Subject: [PATCH] uart: Added logic to regulate data rate
Now uses a data rate thst is proportional to speed.
Could be made a bit better by using the cycle clock count directly,
but this method is a bit clearer
Signed-off-by: Michel Pollet <buserror@gmail.com>
---
simavr/sim/avr_uart.c | 24 ++++++++++++++++++------
simavr/sim/avr_uart.h | 4 ++++
2 files changed, 22 insertions(+), 6 deletions(-)
diff --git a/simavr/sim/avr_uart.c b/simavr/sim/avr_uart.c
index f6000e6..7cb019a 100644
--- a/simavr/sim/avr_uart.c
+++ b/simavr/sim/avr_uart.c
@@ -97,8 +97,9 @@ static uint8_t avr_uart_read(struct avr_t * avr, avr_io_addr_t addr, void * para
// made to trigger potential watchpoints
v = avr_core_watch_read(avr, addr);
- if (!uart_fifo_isempty(&p->input))
- avr_cycle_timer_register_usec(avr, 100, avr_uart_rxc_raise, p); // should be uart speed dependent
+ // should always trigger that timer
+// if (!uart_fifo_isempty(&p->input))
+ avr_cycle_timer_register_usec(avr, p->usec_per_byte, avr_uart_rxc_raise, p);
return v;
}
@@ -113,7 +114,17 @@ static void avr_uart_baud_write(struct avr_t * avr, avr_io_addr_t addr, uint8_t
baud /= 8;
else
baud /= 16;
- printf("UART-%c configured to %04x = %d baud\n", p->name, val, baud);
+
+ const int databits[] = { 5,6,7,8, /* 'reserved', assume 8 */8,8,8, 9 };
+ int db = databits[avr_regbit_get(avr, p->ucsz) | (avr_regbit_get(avr, p->ucsz2) << 2)];
+ int sb = 1 + avr_regbit_get(avr, p->usbs);
+ int word_size = 1 /* start */ + db /* data bits */ + 1 /* parity */ + sb /* stops */;
+
+ printf("UART-%c configured to %04x = %d bps, %d data %d stop\n",
+ p->name, val, baud, db, sb);
+ // TODO: Use the divider value and calculate the straight number of cycles
+ p->usec_per_byte = 1000000 / (baud / word_size);
+ printf("Roughtly %d usec per bytes\n", (int)p->usec_per_byte);
}
static void avr_uart_write(struct avr_t * avr, avr_io_addr_t addr, uint8_t v, void * param)
@@ -124,7 +135,8 @@ static void avr_uart_write(struct avr_t * avr, avr_io_addr_t addr, uint8_t v, vo
avr_core_watch_write(avr, addr, v);
avr_regbit_clear(avr, p->udrc.raised);
- avr_cycle_timer_register_usec(avr, 100, avr_uart_txc_raise, p); // should be uart speed dependent
+ avr_cycle_timer_register_usec(avr,
+ p->usec_per_byte, avr_uart_txc_raise, p); // should be uart speed dependent
if (p->flags & AVR_UART_FLAG_STDIO) {
static char buf[128];
@@ -180,7 +192,7 @@ static void avr_uart_irq_input(struct avr_irq_t * irq, uint32_t value, void * pa
return;
if (uart_fifo_isempty(&p->input))
- avr_cycle_timer_register_usec(avr, 100, avr_uart_rxc_raise, p); // should be uart speed dependent
+ avr_cycle_timer_register_usec(avr, p->usec_per_byte, avr_uart_rxc_raise, p); // should be uart speed dependent
uart_fifo_write(&p->input, value); // add to fifo
// printf("UART IRQ in %02x (%d/%d) %s\n", value, p->input.read, p->input.write, uart_fifo_isfull(&p->input) ? "FULL!!" : "");
@@ -201,7 +213,7 @@ void avr_uart_reset(struct avr_io_t *io)
// DEBUG allow printf without fidding with enabling the uart
avr_regbit_set(avr, p->txen);
-
+ p->usec_per_byte = 100;
}
static int avr_uart_ioctl(struct avr_io_t * port, uint32_t ctl, void * io_param)
diff --git a/simavr/sim/avr_uart.h b/simavr/sim/avr_uart.h
index 4764e72..dc9e805 100644
--- a/simavr/sim/avr_uart.h
+++ b/simavr/sim/avr_uart.h
@@ -92,6 +92,9 @@ typedef struct avr_uart_t {
avr_regbit_t rxen; // receive enabled
avr_regbit_t txen; // transmit enable
avr_regbit_t u2x; // double UART speed
+ avr_regbit_t usbs; // stop bits
+ avr_regbit_t ucsz; // data bits
+ avr_regbit_t ucsz2; // data bits, continued
avr_io_addr_t r_ubrrl,r_ubrrh;
@@ -102,6 +105,7 @@ typedef struct avr_uart_t {
uart_fifo_t input;
uint32_t flags;
+ avr_cycle_count_t usec_per_byte;
} avr_uart_t;
/* takes a uint32_t* as parameter */
--
2.39.5