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uart.c: rx overflow fix and tx simplification 

* fixes the clearing of the rx ringbuffer on rx-overflow
* removes tx_level and tx_cts by restricting the ringbuffer
  to at least one slot empty
* agnostic of the details of the tx irq: works for uarts that
  generate tx interrupts on !tx-full or on tx-empty.
* only rx_produce and tx_consume need to be volatile
This commit is contained in:
Robert Jordens 2015-07-19 01:23:34 -06:00 committed by Sebastien Bourdeauducq
parent 35250f5b11
commit 097248bce9
1 changed files with 39 additions and 36 deletions
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57
software/libbase/uart.c
View File

@ -13,39 +13,37 @@
static char rx_buf[UART_RINGBUFFER_SIZE_RX]; static char rx_buf[UART_RINGBUFFER_SIZE_RX];
static volatile unsigned int rx_produce; static volatile unsigned int rx_produce;
static volatile unsigned int rx_consume; static unsigned int rx_consume;
#define UART_RINGBUFFER_SIZE_TX 128 #define UART_RINGBUFFER_SIZE_TX 128
#define UART_RINGBUFFER_MASK_TX (UART_RINGBUFFER_SIZE_TX-1) #define UART_RINGBUFFER_MASK_TX (UART_RINGBUFFER_SIZE_TX-1)
static char tx_buf[UART_RINGBUFFER_SIZE_TX]; static char tx_buf[UART_RINGBUFFER_SIZE_TX];
static unsigned int tx_produce; static unsigned int tx_produce;
static unsigned int tx_consume; static volatile unsigned int tx_consume;
static volatile int tx_cts;
static volatile int tx_level;
void uart_isr(void) void uart_isr(void)
{ {
unsigned int stat; unsigned int stat, rx_produce_next;
stat = uart_ev_pending_read(); stat = uart_ev_pending_read();
if(stat & UART_EV_RX) { if(stat & UART_EV_RX) {
while(!uart_rxempty_read()) { while(!uart_rxempty_read()) {
rx_produce_next = (rx_produce + 1) & UART_RINGBUFFER_MASK_RX;
if(rx_produce_next != rx_consume) {
rx_buf[rx_produce] = uart_rxtx_read(); rx_buf[rx_produce] = uart_rxtx_read();
rx_produce = (rx_produce + 1) & UART_RINGBUFFER_MASK_RX; rx_produce = rx_produce_next;
}
uart_ev_pending_write(UART_EV_RX); uart_ev_pending_write(UART_EV_RX);
} }
} }
if(stat & UART_EV_TX) { if(stat & UART_EV_TX) {
uart_ev_pending_write(UART_EV_TX); uart_ev_pending_write(UART_EV_TX);
if(tx_level == 0) while((tx_consume != tx_produce) && !uart_txfull_read()) {
tx_cts = 1;
while(tx_level > 0 && !uart_txfull_read()) {
uart_rxtx_write(tx_buf[tx_consume]); uart_rxtx_write(tx_buf[tx_consume]);
tx_consume = (tx_consume + 1) & UART_RINGBUFFER_MASK_TX; tx_consume = (tx_consume + 1) & UART_RINGBUFFER_MASK_TX;
tx_level--;
} }
} }
} }
@ -55,7 +53,12 @@ char uart_read(void)
{ {
char c; char c;
if(irq_getie()) {
while(rx_consume == rx_produce); while(rx_consume == rx_produce);
} else if (rx_consume == rx_produce) {
return 0;
}
c = rx_buf[rx_consume]; c = rx_buf[rx_consume];
rx_consume = (rx_consume + 1) & UART_RINGBUFFER_MASK_RX; rx_consume = (rx_consume + 1) & UART_RINGBUFFER_MASK_RX;
return c; return c;
@ -69,45 +72,45 @@ int uart_read_nonblock(void)
void uart_write(char c) void uart_write(char c)
{ {
unsigned int oldmask; unsigned int oldmask;
unsigned int tx_produce_next = (tx_produce + 1) & UART_RINGBUFFER_MASK_TX;
if(irq_getie()) { if(irq_getie()) {
while(tx_level == UART_RINGBUFFER_SIZE_TX); while(tx_produce_next == tx_consume);
} else if(tx_produce_next == tx_consume) {
return;
} }
oldmask = irq_getmask(); oldmask = irq_getmask();
irq_setmask(0); irq_setmask(oldmask & ~(1 << UART_INTERRUPT));
#if 0
if(tx_cts) { while((tx_consume != tx_produce) && !uart_txfull_read()) {
tx_cts = 0; uart_rxtx_write(tx_buf[tx_consume]);
uart_rxtx_write(c); tx_consume = (tx_consume + 1) & UART_RINGBUFFER_MASK_TX;
} else { }
#endif
if((tx_consume != tx_produce) || uart_txfull_read()) {
tx_buf[tx_produce] = c; tx_buf[tx_produce] = c;
tx_produce = (tx_produce + 1) & UART_RINGBUFFER_MASK_TX; tx_produce = tx_produce_next;
tx_level++; } else {
uart_rxtx_write(c);
} }
irq_setmask(oldmask); irq_setmask(oldmask);
} }
void uart_init(void) void uart_init(void)
{ {
unsigned int mask;
rx_produce = 0; rx_produce = 0;
rx_consume = 0; rx_consume = 0;
tx_produce = 0; tx_produce = 0;
tx_consume = 0; tx_consume = 0;
tx_cts = 1;
tx_level = 0;
uart_ev_pending_write(uart_ev_pending_read()); uart_ev_pending_write(uart_ev_pending_read());
uart_ev_enable_write(UART_EV_TX | UART_EV_RX); uart_ev_enable_write(UART_EV_TX | UART_EV_RX);
mask = irq_getmask(); irq_setmask(irq_getmask() | (1 << UART_INTERRUPT));
mask |= 1 << UART_INTERRUPT;
irq_setmask(mask);
} }
void uart_sync(void) void uart_sync(void)
{ {
while(!tx_cts); while(tx_consume != tx_produce);
} }