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Use interrupts and buffer the UART receive side too.

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This commit is contained in:
Gavan Fantom
2011-05-23 21:41:17 +00:00
parent 4eaff797c9
commit f0efc593ea
1 changed files with 51 additions and 21 deletions
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72
uart.c
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@@ -26,11 +26,15 @@
#define U0THRE ((UREG(LSR) & (1<<5))) /* UART0 transmitter holding register is empty */ #define U0THRE ((UREG(LSR) & (1<<5))) /* UART0 transmitter holding register is empty */
#define U0DR ((UREG(LSR) & (1<<0))) /* UART0 data ready */ #define U0DR ((UREG(LSR) & (1<<0))) /* UART0 data ready */
#define UART_BUFSIZE 128 #define UART_TXBUFSIZE 128
#define UART_RXBUFSIZE 128
char uart_txbuf[UART_BUFSIZE]; char uart_txbuf[UART_TXBUFSIZE];
char uart_rxbuf[UART_RXBUFSIZE];
volatile int uart_txread; volatile int uart_txread;
volatile int uart_txwrite; volatile int uart_txwrite;
volatile int uart_rxread;
volatile int uart_rxwrite;
volatile bool tx_running; volatile bool tx_running;
void __attribute__((interrupt("IRQ"))) uart_interrupt_handler(void); void __attribute__((interrupt("IRQ"))) uart_interrupt_handler(void);
@@ -47,15 +51,17 @@ void init_uart(void)
uart_txread = 0; uart_txread = 0;
uart_txwrite = 0; uart_txwrite = 0;
uart_rxread = 0;
uart_rxwrite = 0;
tx_running = FALSE; tx_running = FALSE;
interrupt_register(UART0, uart_interrupt_handler); interrupt_register(UART0, uart_interrupt_handler);
UREG(IER) = 0x02; /* THRE interrupt enable */ UREG(IER) = 0x03; /* RBR and THRE interrupt enable */
} }
void putch(char c) { void putch(char c) {
/* Wait for space in the buffer */ /* Wait for space in the buffer */
while (uart_txread == ((uart_txwrite+1) % UART_BUFSIZE)); while (uart_txread == ((uart_txwrite+1) % UART_TXBUFSIZE));
if (uart_txread == uart_txwrite) { if (uart_txread == uart_txwrite) {
if (U0THRE) { if (U0THRE) {
@@ -66,12 +72,12 @@ void putch(char c) {
} }
uart_txbuf[uart_txwrite] = c; uart_txbuf[uart_txwrite] = c;
uart_txwrite = (uart_txwrite + 1) % UART_BUFSIZE; uart_txwrite = (uart_txwrite + 1) % UART_TXBUFSIZE;
if (!tx_running) { if (!tx_running) {
if (uart_txread != uart_txwrite) { if (uart_txread != uart_txwrite) {
tx_running = TRUE; tx_running = TRUE;
uart_txread = (uart_txread + 1) % UART_BUFSIZE; uart_txread = (uart_txread + 1) % UART_TXBUFSIZE;
UREG(THR) = c; UREG(THR) = c;
} }
} }
@@ -86,29 +92,48 @@ void __attribute__((interrupt("IRQ"))) uart_interrupt_handler(void)
* to treat them as such in this handler, so let the compiler * to treat them as such in this handler, so let the compiler
* have an easier time. * have an easier time.
*/ */
int local_txwrite = uart_txwrite; int local_txwrite;
int local_txread = uart_txread; int local_txread;
int local_rxwrite;
int local_rxread;
source = UREG(IIR); source = UREG(IIR);
/* For now we assume that all interrupts are actually THR empty switch (source & 0x0e) {
* interrupts. Actually check this when we do more things with case 0x4: /* Receive Data Available */
* the UART case 0xc: /* Character Time-out Indicator */
*/ local_rxwrite = uart_rxwrite;
local_rxread = uart_rxread;
while (U0DR) {
unsigned char c = UREG(RBR);
if (local_rxread !=
((local_rxwrite+1) % UART_RXBUFSIZE)) {
uart_rxbuf[local_rxwrite] = c;
local_rxwrite = (local_rxwrite + 1) %
UART_RXBUFSIZE;
}
}
uart_rxwrite = local_rxwrite;
break;
if (U0THRE) { case 0x2: /* THRE interrupt */
local_txwrite = uart_txwrite;
local_txread = uart_txread;
for (i = 0; (i < 16) && (local_txwrite != local_txread); i++) { for (i = 0; (i < 16) && (local_txwrite != local_txread); i++) {
UREG(THR) = uart_txbuf[local_txread]; UREG(THR) = uart_txbuf[local_txread];
local_txread = (local_txread + 1) % UART_BUFSIZE; local_txread = (local_txread + 1) % UART_TXBUFSIZE;
active = TRUE; active = TRUE;
} }
uart_txread = local_txread;
if (!active)
tx_running = FALSE;
break;
case 0x6: /* Receive Line Status */
default: /* Anything else */
break;
} }
uart_txread = local_txread;
if (!active)
tx_running = FALSE;
interrupt_clear(); interrupt_clear();
} }
@@ -148,8 +173,13 @@ void puthex(unsigned int n) {
} }
char getch(void) { char getch(void) {
while (!U0DR) { char c;
while (uart_rxread == uart_rxwrite) {
FP0XVAL ^= 0x04000000; FP0XVAL ^= 0x04000000;
} }
return UREG(RBR);
c = uart_rxbuf[uart_rxread];
uart_rxread = (uart_rxread + 1) % UART_RXBUFSIZE;
return c;
} }