/*
 * Copyright (c) 2011 Jan Vesely
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/**  @addtogroup libusbhost
 * @{
 */
/** @file
 *
 * Bandwidth calculation functions. Shared among uhci, ohci and ehci drivers.
 */

#include <assert.h>
#include <stdlib.h>

#include "endpoint.h"
#include "bus.h"

#include "bandwidth.h"

/**
 * Calculate bandwidth that needs to be reserved for communication with EP.
 * Calculation follows USB 1.1 specification.
 * @param ep Registered endpoint
 * @param size Number of bytes to transfer.
 * @param max_packet_size Maximum bytes in one packet.
 */
ssize_t bandwidth_count_usb11(endpoint_t *ep, size_t size)
{
	assert(ep);
	assert(ep->device);

	const usb_transfer_type_t type = ep->transfer_type;

	/* We care about bandwidth only for interrupt and isochronous. */
	if ((type != USB_TRANSFER_INTERRUPT)
	    && (type != USB_TRANSFER_ISOCHRONOUS)) {
		return 0;
	}

	const size_t max_packet_size = ep->max_packet_size;

	const unsigned packet_count =
	    (size + max_packet_size - 1) / max_packet_size;
	/* TODO: It may be that ISO and INT transfers use only one packet per
	 * transaction, but I did not find text in USB spec to confirm this */
	/* NOTE: All data packets will be considered to be max_packet_size */
	switch (ep->device->speed)
	{
	case USB_SPEED_LOW:
		assert(type == USB_TRANSFER_INTERRUPT);
		/* Protocol overhead 13B
		 * (3 SYNC bytes, 3 PID bytes, 2 Endpoint + CRC bytes, 2
		 * CRC bytes, and a 3-byte interpacket delay)
		 * see USB spec page 45-46. */
		/* Speed penalty 8: low speed is 8-times slower*/
		return packet_count * (13 + max_packet_size) * 8;
	case USB_SPEED_FULL:
		/* Interrupt transfer overhead see above
		 * or page 45 of USB spec */
		if (type == USB_TRANSFER_INTERRUPT)
			return packet_count * (13 + max_packet_size);

		assert(type == USB_TRANSFER_ISOCHRONOUS);
		/* Protocol overhead 9B
		 * (2 SYNC bytes, 2 PID bytes, 2 Endpoint + CRC bytes, 2 CRC
		 * bytes, and a 1-byte interpacket delay)
		 * see USB spec page 42 */
		return packet_count * (9 + max_packet_size);
	default:
		return 0;
	}
}

/** 
 * Calculate bandwidth that needs to be reserved for communication with EP.
 * Calculation follows USB 2.0 specification, chapter 5.11.3.
 *
 * @param speed Device's speed.
 * @param type Type of the transfer.
 * @param size Number of byte to transfer.
 * @param max_packet_size Maximum bytes in one packet.
 * @return Number of nanoseconds transaction with @c size bytes payload will
 *         take.
 */
ssize_t bandwidth_count_usb20(endpoint_t *ep, size_t size)
{
	assert(ep);

	const usb_transfer_type_t type = ep->transfer_type;

	/* We care about bandwidth only for interrupt and isochronous. */
	if ((type != USB_TRANSFER_INTERRUPT)
	    && (type != USB_TRANSFER_ISOCHRONOUS)) {
		return 0;
	}

	// FIXME: Come up with some upper bound for these (in ns).
	const size_t host_delay = 0;
	const size_t hub_ls_setup = 0;

	// Approx. Floor(3.167 + BitStuffTime(Data_bc))
	const size_t base_time = (size * 8 + 19) / 6;

	switch (ep->device->speed) {
	case USB_SPEED_LOW:
		if (ep->direction == USB_DIRECTION_IN)
			return 64060 + (2 * hub_ls_setup) + (677 * base_time) + host_delay;
		else
			return 64107 + (2 * hub_ls_setup) + (667 * base_time) + host_delay;

	case USB_SPEED_FULL:
		if (ep->transfer_type == USB_TRANSFER_INTERRUPT)
			return 9107 + 84 * base_time + host_delay;

		if (ep->direction == USB_DIRECTION_IN)
			return 7268 + 84 * base_time + host_delay;
		else
			return 6265 + 84 * base_time + host_delay;

	case USB_SPEED_HIGH:
		if (ep->transfer_type == USB_TRANSFER_INTERRUPT)
			return (3648 + 25 * base_time + 11) / 12 + host_delay;
		else
			return (5280 + 25 * base_time + 11) / 12 + host_delay;

	default:
		return 0;
	}
}