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Make XON/XOFF flow control actually work. Still disabled by default.

This commit is contained in:
Markus Hitter 2010-09-08 19:10:54 +02:00
parent b2e1cfd8b5
commit 8b5e21be51
2 changed files with 25 additions and 11 deletions
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12
dda_queue.c
View File

@ -21,6 +21,10 @@ uint8_t queue_empty() {
return ((mb_tail == mb_head) && (movebuffer[mb_tail].live == 0))?255:0; return ((mb_tail == mb_head) && (movebuffer[mb_tail].live == 0))?255:0;
} }
// -------------------------------------------------------
// This is the one function called by the timer interrupt.
// It calls a few other functions, though.
// -------------------------------------------------------
void queue_step() { void queue_step() {
disableTimerInterrupt(); disableTimerInterrupt();
@ -71,8 +75,9 @@ void enqueue(TARGET *t) {
mb_head = h; mb_head = h;
#ifdef XONXOFF #ifdef XONXOFF
// if queue is full, stop transmission // If the queue has only two slots remaining, stop transmission. More
if (queue_full()) // characters might come in until the stop takes effect.
if (((mb_tail - mb_head - 1) & (MOVEBUFFER_SIZE - 1)) < (MOVEBUFFER_SIZE - 2))
xoff(); xoff();
#endif #endif
@ -105,8 +110,7 @@ void enqueue_temp_wait() {
mb_head = h; mb_head = h;
#ifdef XONXOFF #ifdef XONXOFF
// if queue is full, stop transmission if (((mb_tail - mb_head - 1) & (MOVEBUFFER_SIZE - 1)) < (MOVEBUFFER_SIZE - 2))
if (queue_full())
xoff(); xoff();
#endif #endif

24
serial.c
View File

@ -48,8 +48,7 @@ volatile uint8_t txbuf[BUFSIZE];
#ifdef XONXOFF #ifdef XONXOFF
#define FLOWFLAG_SEND_XON 1 #define FLOWFLAG_SEND_XON 1
#define FLOWFLAG_SEND_XOFF 2 #define FLOWFLAG_SEND_XOFF 2
#define FLOWFLAG_SENT_XON 4 #define FLOWFLAG_STATE_XON 4
#define FLOWFLAG_SENT_XOFF 8
// initially, send an XON // initially, send an XON
volatile uint8_t flowflags = FLOWFLAG_SEND_XON; volatile uint8_t flowflags = FLOWFLAG_SEND_XON;
#endif #endif
@ -88,11 +87,11 @@ ISR(USART_UDRE_vect)
#ifdef XONXOFF #ifdef XONXOFF
if (flowflags & FLOWFLAG_SEND_XON) { if (flowflags & FLOWFLAG_SEND_XON) {
UDR0 = ASCII_XON; UDR0 = ASCII_XON;
flowflags = (flowflags & ~FLOWFLAG_SEND_XON) | FLOWFLAG_SENT_XON; flowflags = FLOWFLAG_STATE_XON;
} }
else if (flowflags & FLOWFLAG_SEND_XOFF) { else if (flowflags & FLOWFLAG_SEND_XOFF) {
UDR0 = ASCII_XOFF; UDR0 = ASCII_XOFF;
flowflags = (flowflags & ~FLOWFLAG_SEND_XOFF) | FLOWFLAG_SENT_XOFF; flowflags = 0;
} }
else else
#endif #endif
@ -193,15 +192,26 @@ void serial_writestr_P(PGM_P data)
#ifdef XONXOFF #ifdef XONXOFF
void xon() { void xon() {
if (flowflags & FLOWFLAG_SENT_XOFF) // disable TX interrupt
UCSR0B &= ~MASK(UDRIE0);
if ((flowflags & FLOWFLAG_STATE_XON) == 0)
flowflags = FLOWFLAG_SEND_XON; flowflags = FLOWFLAG_SEND_XON;
else
flowflags = FLOWFLAG_STATE_XON; // purge a possible FLOWFLAG_SEND_XOFF
// enable TX interrupt so we can send this character // enable TX interrupt so we can send this character
UCSR0B |= MASK(UDRIE0); UCSR0B |= MASK(UDRIE0);
} }
void xoff() { void xoff() {
flowflags = FLOWFLAG_SEND_XOFF; UCSR0B &= ~MASK(UDRIE0);
// enable TX interrupt so we can send this character
if (flowflags & FLOWFLAG_STATE_XON)
flowflags = FLOWFLAG_SEND_XOFF | FLOWFLAG_STATE_XON;
else
flowflags = 0;
UCSR0B |= MASK(UDRIE0); UCSR0B |= MASK(UDRIE0);
} }
#endif #endif