#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <stdlib.h>
#include <string.h>

#include "Evas_Data.h"
#include "evas_mempool.h"

//#define NOPOOL

typedef struct _Pool Pool;

struct _Pool
{
   int usage;
   void *base;
   Pool *prev, *next;
};


Pool *
_evas_mp_pool_new(Evas_Mempool *pool)
{
#ifdef NOPOOL
   static Pool thepool;
   return &thepool;
#else
   Pool *p;
   void **ptr;
   int item_alloc, i;

   item_alloc =
      ((pool->item_size + sizeof(void *) - 1) / sizeof(void *)) * sizeof(void *);
   p = malloc(sizeof(Pool) + (pool->pool_size * item_alloc));
   ptr = (void **)(((unsigned char *)p) + sizeof(Pool));
   p->usage = 0;
   p->base = ptr;
   for (i = 0; i < pool->pool_size - 1; i++)
     {
        *ptr = (void **)(((unsigned char *)ptr) + item_alloc);
        ptr = *ptr;
     }
   *ptr = NULL;
   return p;
#endif
}

void
_evas_mp_pool_free(Pool *p)
{
#if !defined(NOPOOL)
   free(p);
#endif
}

void *
evas_mempool_malloc(Evas_Mempool *pool, int size)
{
#ifdef NOPOOL
   return malloc(size);
#else
   Pool *p;
   void *mem;

   for (p = pool->first; p; p = p->next) // look 4 pool from 2nd bucket on
     {
        if (p->base) // base is not NULL - has a free slot
          {
             if (p->prev)
               {
                  if (pool->last == p)
                     pool->last = p->prev;

                  p->prev->next = p->next;
                  p->prev = NULL;
                  p->next = pool->first;
                  p->next->prev = p;
                  pool->first = p;
               }

             break;
          }
     }
   if (!p) // we have reached the end of the list - no free pools
     {
        p = _evas_mp_pool_new(pool);
        if (!p)
           return NULL;

        p->prev = NULL;
        p->next = pool->first;
        if (p->next)
           p->next->prev = p;

        if (!pool->last)
           pool->last = p;

        pool->first = p;
     }

   mem = p->base; // this points to the next free block - so take it
   p->base = *((void **)mem); // base now points to the next free block
   if (!p->base) // move to end - it just filled up
      if (p->next)
        {
           if (p->prev)
              p->prev->next = p->next;
           else
              pool->first = p->next;

           p->next->prev = p->prev;
           ((Pool *)pool->last)->next = p;
           p->prev = pool->last;
           p->next = NULL;
           pool->last = p;
        }

   p->usage++;
   pool->usage++;
   return mem;
#endif
}

void
evas_mempool_free(Evas_Mempool *pool, void *ptr)
{
#ifdef NOPOOL
   free(ptr);
#else
   Pool *p;
   void *pmem;
   int item_alloc, psize;

   item_alloc =
      ((pool->item_size + sizeof(void *) - 1) / sizeof(void *)) * sizeof(void *);
   psize = item_alloc * pool->pool_size;
   for (p = (Pool *)(pool->first); p; p = p->next) // look 4 pool
     {
        pmem = (void *)(((unsigned char *)p) + sizeof(Pool)); // pool mem base
        if ((ptr >= pmem) &&
            ((unsigned char *)ptr < (((unsigned char *)pmem) + psize))) // is it in pool mem?
          {
             *((void **)ptr) = p->base; // freed node points to prev free node
             p->base = ptr; // next free node is now the one we freed
             p->usage--;
             pool->usage--;
             if (p->usage == 0) // free bucket
               {
                  if (p->prev)
                     p->prev->next = p->next;

                  if (p->next)
                     p->next->prev = p->prev;

                  if (pool->last == p)
                     pool->last = p->prev;

                  if (pool->first == p)
                     pool->first = p->next;

                  _evas_mp_pool_free(p);
               }
             else if (p->prev) // if not the first - move to front
               {
                  p->prev->next = p->next;
                  if (p->next)
                     p->next->prev = p->prev;

                  if (pool->last == p)
                     pool->last = p->prev;

                  p->prev = NULL;
                  p->next = pool->first;
                  p->next->prev = p;
                  pool->first = p;
               }

             break;
          }
     }
#endif
}


void *
evas_mempool_calloc(Evas_Mempool *pool, int size)
{
#ifdef NOPOOL
   return calloc(1, size);
#else
   void *mem;

   mem = evas_mempool_malloc(pool, size);
   memset(mem, 0, size);
   return mem;
#endif
}