/*
 *  VAS_EBOOT  --  GRand Unified Bootloader
 *  Copyright (C) 2010 Free Software Foundation, Inc.
 *
 *  VAS_EBOOT is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  VAS_EBOOT is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with VAS_EBOOT.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <VasEBoot/err.h>
#include <VasEBoot/misc.h>
#include <VasEBoot/mm.h>
#include <VasEBoot/net/netbuff.h>

VasEBoot_err_t
VasEBoot_netbuff_put (struct VasEBoot_net_buff *nb, VasEBoot_size_t len)
{
  nb->tail += len;
  if (nb->tail > nb->end)
    return VasEBoot_error (VAS_EBOOT_ERR_BUG, "put out of the packet range.");
  return VAS_EBOOT_ERR_NONE;
}

VasEBoot_err_t
VasEBoot_netbuff_unput (struct VasEBoot_net_buff *nb, VasEBoot_size_t len)
{
  nb->tail -= len;
  if (nb->tail < nb->head)
    return VasEBoot_error (VAS_EBOOT_ERR_BUG,
		       "unput out of the packet range.");
  return VAS_EBOOT_ERR_NONE;
}

VasEBoot_err_t
VasEBoot_netbuff_push (struct VasEBoot_net_buff *nb, VasEBoot_size_t len)
{
  nb->data -= len;
  if (nb->data < nb->head)
    return VasEBoot_error (VAS_EBOOT_ERR_BUG,
		       "push out of the packet range.");
  return VAS_EBOOT_ERR_NONE;
}

VasEBoot_err_t
VasEBoot_netbuff_pull (struct VasEBoot_net_buff *nb, VasEBoot_size_t len)
{
  nb->data += len;
  if (nb->data > nb->end || nb->data > nb->tail)
    return VasEBoot_error (VAS_EBOOT_ERR_BUG,
		       "pull out of the packet range.");
  return VAS_EBOOT_ERR_NONE;
}

VasEBoot_err_t
VasEBoot_netbuff_reserve (struct VasEBoot_net_buff *nb, VasEBoot_size_t len)
{
  nb->data += len;
  nb->tail += len;
  if ((nb->tail > nb->end) || (nb->data > nb->end))
    return VasEBoot_error (VAS_EBOOT_ERR_BUG,
		       "reserve out of the packet range.");
  return VAS_EBOOT_ERR_NONE;
}

struct VasEBoot_net_buff *
VasEBoot_netbuff_alloc (VasEBoot_size_t len)
{
  struct VasEBoot_net_buff *nb;
  void *data;

  COMPILE_TIME_ASSERT (NETBUFF_ALIGN % sizeof (VasEBoot_properly_aligned_t) == 0);

  /*
   * The largest size of a TCP packet is 64 KiB, and everything else
   * should be a lot smaller - most MTUs are 1500 or less. Cap data
   * size at 64 KiB + a buffer.
   */
  if (len > 0xffffUL + 0x1000UL)
    {
      VasEBoot_error (VAS_EBOOT_ERR_BUG,
                  "attempted to allocate a packet that is too big");
      return NULL;
    }

  if (len < NETBUFFMINLEN)
    len = NETBUFFMINLEN;

  len = ALIGN_UP (len, NETBUFF_ALIGN);

#ifdef VAS_EBOOT_MACHINE_EMU
  data = VasEBoot_malloc (len + sizeof (*nb));
#else
  data = VasEBoot_memalign (NETBUFF_ALIGN, len + sizeof (*nb));
#endif
  if (!data)
    return NULL;
  nb = (struct VasEBoot_net_buff *) ((VasEBoot_properly_aligned_t *) data
				 + len / sizeof (VasEBoot_properly_aligned_t));
  nb->head = nb->data = nb->tail = data;
  nb->end = (VasEBoot_uint8_t *) nb;
  return nb;
}

struct VasEBoot_net_buff *
VasEBoot_netbuff_make_pkt (VasEBoot_size_t len)
{
  struct VasEBoot_net_buff *nb;
  VasEBoot_err_t err;
  nb = VasEBoot_netbuff_alloc (len + 512);
  if (!nb)
    return NULL;
  err = VasEBoot_netbuff_reserve (nb, len + 512);
  if (err)
    goto fail;
  err = VasEBoot_netbuff_push (nb, len);
  if (err)
    goto fail;
  return nb;
 fail:
  VasEBoot_netbuff_free (nb);
  return NULL;
}

void
VasEBoot_netbuff_free (struct VasEBoot_net_buff *nb)
{
  if (!nb)
    return;
  VasEBoot_free (nb->head);
}

VasEBoot_err_t
VasEBoot_netbuff_clear (struct VasEBoot_net_buff *nb)
{
  nb->data = nb->tail = nb->head;
  return VAS_EBOOT_ERR_NONE;
}