controller/Output/pjrcUSB/arm/usb_keyboard.c

/* Teensyduino Core Library
 * http://www.pjrc.com/teensy/
 * Copyright (c) 2013 PJRC.COM, LLC.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * 1. The above copyright notice and this permission notice shall be 
 * included in all copies or substantial portions of the Software.
 *
 * 2. If the Software is incorporated into a build system that allows 
 * selection among a list of target devices, then similar target
 * devices manufactured by PJRC.COM must be included in the list of
 * target devices and selectable in the same manner.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "usb_dev.h"
#include "usb_keyboard.h"
#include <Lib/OutputLib.h>
#include <string.h> // for memcpy()


// Maximum number of transmit packets to queue so we don't starve other endpoints for memory
#define TX_PACKET_LIMIT 4

static uint8_t transmit_previous_timeout=0;

// When the PC isn't listening, how long do we wait before discarding data?
#define TX_TIMEOUT_MSEC 50

#if F_CPU == 96000000
  #define TX_TIMEOUT (TX_TIMEOUT_MSEC * 596)
#elif F_CPU == 48000000
  #define TX_TIMEOUT (TX_TIMEOUT_MSEC * 428)
#elif F_CPU == 24000000
  #define TX_TIMEOUT (TX_TIMEOUT_MSEC * 262)
#endif


// send the contents of keyboard_keys and keyboard_modifier_keys
int usb_keyboard_send(void)
{
	uint32_t wait_count=0;
	usb_packet_t *tx_packet;

	while (1) {
		if (!usb_configuration) {
			return -1;
		}
		if (usb_tx_packet_count(KEYBOARD_ENDPOINT) < TX_PACKET_LIMIT) {
			tx_packet = usb_malloc();
			if (tx_packet) break;
		}
		if (++wait_count > TX_TIMEOUT || transmit_previous_timeout) {
			transmit_previous_timeout = 1;
			return -1;
		}
		yield();
	}
	*(tx_packet->buf) = USBKeys_Modifiers;
	*(tx_packet->buf + 1) = 0;
	memcpy(tx_packet->buf + 2, USBKeys_Array, USB_MAX_KEY_SEND);
	tx_packet->len = 8;
	usb_tx(KEYBOARD_ENDPOINT, tx_packet);

	return 0;
}