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/** @file

 *

 * Dynamic memory manager

 *

 */

/*

 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without modification,

 * are permitted provided that the following conditions are met:

 *

 * 1. Redistributions of source code must retain the above copyright notice,

 *    this list of conditions and the following disclaimer.

 * 2. 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.

 * 3. 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.

 *

 * This file is part of the lwIP TCP/IP stack.

 *

 * Author: Adam Dunkels <adam@sics.se>

 *

 */

#include <string.h>

#include "lwip/arch.h"

#include "lwip/opt.h"

#include "lwip/def.h"

#include "lwip/mem.h"

#include "lwip/sys.h"

#include "lwip/stats.h"

struct mem {

  mem_size_t next, prev;

#if MEM_ALIGNMENT == 1

  u8_t used;

#elif MEM_ALIGNMENT == 2

  u16_t used;

#elif MEM_ALIGNMENT == 4

  u32_t used;

#elif MEM_ALIGNMENT == 8

  u64_t used;

#else

#error "unhandled MEM_ALIGNMENT size"

#endif /* MEM_ALIGNMENT */

};

static struct mem *ram_end;

static u8_t ram[MEM_SIZE + sizeof(struct mem) + MEM_ALIGNMENT];

#define MIN_SIZE 12

#if 0 /* this one does not align correctly for some, resulting in crashes */

#define SIZEOF_STRUCT_MEM (unsigned int)MEM_ALIGN_SIZE(sizeof(struct mem))

#else

#define SIZEOF_STRUCT_MEM (sizeof(struct mem) + \

                          (((sizeof(struct mem) % MEM_ALIGNMENT) == 0)? 0 : \

                          (4 - (sizeof(struct mem) % MEM_ALIGNMENT))))

#endif

static struct mem *lfree;   /* pointer to the lowest free block */

static sys_sem_t mem_sem;

static void

plug_holes(struct mem *mem)

{

  struct mem *nmem;

  struct mem *pmem;

  LWIP_ASSERT("plug_holes: mem >= ram", (u8_t *)mem >= ram);

  LWIP_ASSERT("plug_holes: mem < ram_end", (u8_t *)mem < (u8_t *)ram_end);

  LWIP_ASSERT("plug_holes: mem->used == 0", mem->used == 0);

  /* plug hole forward */

  LWIP_ASSERT("plug_holes: mem->next <= MEM_SIZE", mem->next <= MEM_SIZE);

  nmem = (struct mem *)&ram[mem->next];

  if (mem != nmem && nmem->used == 0 && (u8_t *)nmem != (u8_t *)ram_end) {

    if (lfree == nmem) {

      lfree = mem;

    }

    mem->next = nmem->next;

    ((struct mem *)&ram[nmem->next])->prev = (u8_t *)mem - ram;

  }

  /* plug hole backward */

  pmem = (struct mem *)&ram[mem->prev];

  if (pmem != mem && pmem->used == 0) {

    if (lfree == mem) {

      lfree = pmem;

    }

    pmem->next = mem->next;

    ((struct mem *)&ram[mem->next])->prev = (u8_t *)pmem - ram;

  }

}

void

mem_init(void)

{

  struct mem *mem;

  memset(ram, 0, MEM_SIZE);

  mem = (struct mem *)ram;

  mem->next = MEM_SIZE;

  mem->prev = 0;

  mem->used = 0;

  ram_end = (struct mem *)&ram[MEM_SIZE];

  ram_end->used = 1;

  ram_end->next = MEM_SIZE;

  ram_end->prev = MEM_SIZE;

  mem_sem = sys_sem_new(1);

  lfree = (struct mem *)ram;

#if MEM_STATS

  lwip_stats.mem.avail = MEM_SIZE;

#endif /* MEM_STATS */

}

void

mem_free(void *rmem)

{

  struct mem *mem;

  if (rmem == NULL) {

    LWIP_DEBUGF(MEM_DEBUG | DBG_TRACE | 2, ("mem_free(p == NULL) was called.\n"));

    return;

  }

  sys_sem_wait(mem_sem);

  LWIP_ASSERT("mem_free: legal memory", (u8_t *)rmem >= (u8_t *)ram &&

    (u8_t *)rmem < (u8_t *)ram_end);

  if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) {

    LWIP_DEBUGF(MEM_DEBUG | 3, ("mem_free: illegal memory\n"));

#if MEM_STATS

    ++lwip_stats.mem.err;

#endif /* MEM_STATS */

    sys_sem_signal(mem_sem);

    return;

  }

  mem = (struct mem *)((u8_t *)rmem - SIZEOF_STRUCT_MEM);

  LWIP_ASSERT("mem_free: mem->used", mem->used);

  mem->used = 0;

  if (mem < lfree) {

    lfree = mem;

  }

#if MEM_STATS

  lwip_stats.mem.used -= mem->next - ((u8_t *)mem - ram);

#endif /* MEM_STATS */

  plug_holes(mem);

  sys_sem_signal(mem_sem);

}

void *

mem_reallocm(void *rmem, mem_size_t newsize)

{

  void *nmem;

  nmem = mem_malloc(newsize);

  if (nmem == NULL) {

    return mem_realloc(rmem, newsize);

  }

  memcpy(nmem, rmem, newsize);

  mem_free(rmem);

  return nmem;

}

void *

mem_realloc(void *rmem, mem_size_t newsize)

{

  mem_size_t size;

  mem_size_t ptr, ptr2;

  struct mem *mem, *mem2;

  /* Expand the size of the allocated memory region so that we can

     adjust for alignment. */

  if ((newsize % MEM_ALIGNMENT) != 0) {

   newsize += MEM_ALIGNMENT - ((newsize + SIZEOF_STRUCT_MEM) % MEM_ALIGNMENT);

  }

  if (newsize > MEM_SIZE) {

    return NULL;

  }

  sys_sem_wait(mem_sem);

  LWIP_ASSERT("mem_realloc: legal memory", (u8_t *)rmem >= (u8_t *)ram &&

   (u8_t *)rmem < (u8_t *)ram_end);

  if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) {

    LWIP_DEBUGF(MEM_DEBUG | 3, ("mem_realloc: illegal memory\n"));

    return rmem;

  }

  mem = (struct mem *)((u8_t *)rmem - SIZEOF_STRUCT_MEM);

  ptr = (u8_t *)mem - ram;

  size = mem->next - ptr - SIZEOF_STRUCT_MEM;

#if MEM_STATS

  lwip_stats.mem.used -= (size - newsize);

#endif /* MEM_STATS */

  if (newsize + SIZEOF_STRUCT_MEM + MIN_SIZE < size) {

    ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize;

    mem2 = (struct mem *)&ram[ptr2];

    mem2->used = 0;

    mem2->next = mem->next;

    mem2->prev = ptr;

    mem->next = ptr2;

    if (mem2->next != MEM_SIZE) {

      ((struct mem *)&ram[mem2->next])->prev = ptr2;

    }

    plug_holes(mem2);

  }

  sys_sem_signal(mem_sem);

  return rmem;

}

void *

mem_malloc(mem_size_t size)

{

  mem_size_t ptr, ptr2;

  struct mem *mem, *mem2;

  if (size == 0) {

    return NULL;

  }

  /* Expand the size of the allocated memory region so that we can

     adjust for alignment. */

  if ((size % MEM_ALIGNMENT) != 0) {

    size += MEM_ALIGNMENT - ((size + SIZEOF_STRUCT_MEM) % MEM_ALIGNMENT);

  }

  if (size > MEM_SIZE) {

    return NULL;

  }

  sys_sem_wait(mem_sem);

  for (ptr = (u8_t *)lfree - ram; ptr < MEM_SIZE; ptr = ((struct mem *)&ram[ptr])->next) {

    mem = (struct mem *)&ram[ptr];

    if (!mem->used &&

       mem->next - (ptr + SIZEOF_STRUCT_MEM) >= size + SIZEOF_STRUCT_MEM) {

      ptr2 = ptr + SIZEOF_STRUCT_MEM + size;

      mem2 = (struct mem *)&ram[ptr2];

      mem2->prev = ptr;

      mem2->next = mem->next;

      mem->next = ptr2;

      if (mem2->next != MEM_SIZE) {

        ((struct mem *)&ram[mem2->next])->prev = ptr2;

      }

      mem2->used = 0;

      mem->used = 1;

#if MEM_STATS

      lwip_stats.mem.used += (size + SIZEOF_STRUCT_MEM);

      /*      if (lwip_stats.mem.max < lwip_stats.mem.used) {

        lwip_stats.mem.max = lwip_stats.mem.used;

  } */

      if (lwip_stats.mem.max < ptr2) {

        lwip_stats.mem.max = ptr2;

      }

#endif /* MEM_STATS */

      if (mem == lfree) {

  /* Find next free block after mem */

        while (lfree->used && lfree != ram_end) {

    lfree = (struct mem *)&ram[lfree->next];

        }

        LWIP_ASSERT("mem_malloc: !lfree->used", !lfree->used);

      }

      sys_sem_signal(mem_sem);

      LWIP_ASSERT("mem_malloc: allocated memory not above ram_end.",

       (mem_ptr_t)mem + SIZEOF_STRUCT_MEM + size <= (mem_ptr_t)ram_end);

      LWIP_ASSERT("mem_malloc: allocated memory properly aligned.",

       (unsigned long)((u8_t *)mem + SIZEOF_STRUCT_MEM) % MEM_ALIGNMENT == 0);

      return (u8_t *)mem + SIZEOF_STRUCT_MEM;

    }

  }

  LWIP_DEBUGF(MEM_DEBUG | 2, ("mem_malloc: could not allocate %"S16_F" bytes\n", (s16_t)size));

#if MEM_STATS

  ++lwip_stats.mem.err;

#endif /* MEM_STATS */  

  sys_sem_signal(mem_sem);

  return NULL;

}