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