usb_extra.c


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#include <avr/interrupt.h>
#include "usb_extra.h"

int8_t usb_extra_send(uint8_t bits)
{
	uint8_t intr_state, timeout;

	if (!usb_configured()) return -1;
	intr_state = SREG;
	cli();
	UENUM = EXTRA_ENDPOINT;
	timeout = UDFNUML + 50;
	while (1) {
		// are we ready to transmit?
		if (UEINTX & (1<<RWAL)) break;
		SREG = intr_state;
		// has the USB gone offline?
		if (!usb_configured()) return -1;
		// have we waited too long?
		if (UDFNUML == timeout) return -1;
		// get ready to try checking again
		intr_state = SREG;
		cli();
		UENUM = EXTRA_ENDPOINT;
	}

	UEDATX = 1; // report id
	UEDATX = bits;

	UEINTX = 0x3A;
	SREG = intr_state;
	return 0;
}