80 lines
1.7 KiB
C
80 lines
1.7 KiB
C
#include <avr/interrupt.h>
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#include "sendchar.h"
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#include "usb_debug.h"
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// the time remaining before we transmit any partially full
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// packet, or send a zero length packet.
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volatile uint8_t debug_flush_timer=0;
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int8_t sendchar(uint8_t c)
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{
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static uint8_t previous_timeout=0;
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uint8_t timeout, intr_state;
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// if we're not online (enumerated and configured), error
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if (!usb_configured()) return -1;
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// interrupts are disabled so these functions can be
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// used from the main program or interrupt context,
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// even both in the same program!
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intr_state = SREG;
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cli();
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UENUM = DEBUG_TX_ENDPOINT;
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// if we gave up due to timeout before, don't wait again
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if (previous_timeout) {
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if (!(UEINTX & (1<<RWAL))) {
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SREG = intr_state;
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return -1;
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}
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previous_timeout = 0;
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}
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// wait for the FIFO to be ready to accept data
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timeout = UDFNUML + 4;
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while (1) {
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// are we ready to transmit?
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if (UEINTX & (1<<RWAL)) break;
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SREG = intr_state;
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// have we waited too long?
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if (UDFNUML == timeout) {
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previous_timeout = 1;
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return -1;
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}
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// has the USB gone offline?
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if (!usb_configured()) return -1;
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// get ready to try checking again
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intr_state = SREG;
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cli();
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UENUM = DEBUG_TX_ENDPOINT;
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}
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// actually write the byte into the FIFO
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UEDATX = c;
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// if this completed a packet, transmit it now!
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if (!(UEINTX & (1<<RWAL))) {
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UEINTX = 0x3A;
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debug_flush_timer = 0;
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} else {
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debug_flush_timer = 2;
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}
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SREG = intr_state;
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return 0;
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}
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// immediately transmit any buffered output.
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void usb_debug_flush_output(void)
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{
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uint8_t intr_state;
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intr_state = SREG;
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cli();
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if (debug_flush_timer) {
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UENUM = DEBUG_TX_ENDPOINT;
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while ((UEINTX & (1<<RWAL))) {
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UEDATX = 0;
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}
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UEINTX = 0x3A;
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debug_flush_timer = 0;
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}
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SREG = intr_state;
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}
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