#include <stddef.h>
#include "alloc.h"
#include "list.h"

#ifndef FALSE
#define FALSE 0
#endif
#ifndef TRUE
#define TRUE 1
#endif

struct block_t
{
    link_t      link;
    uint8_t     data[1];
};

void
allocator_init (allocator_t *allocator)
{
    list_init (&allocator->blocks);
}

void *
allocator_alloc (allocator_t *allocator, size_t size)
{
    block_t *block = malloc (sizeof (block_t) - 1 + size);

    if (!block)
        return NULL;
    
    list_prepend (&allocator->blocks, &block->link);

    return &(block->data[1]);
}

#define GET_BLOCK(mem)                                                  \
    ((block_t *)(((uint8_t *)mem) - offsetof (block_t, data)))

void *
allocator_realloc (allocator_t *allocator, void *mem, size_t size)
{
    block_t *old_block, *new_block;

    if (mem == NULL)
        return allocator_alloc (allocator, size);
    
    old_block = GET_BLOCK (mem);
    list_unlink (&old_block->link);

    new_block = realloc (old_block, sizeof (block_t) - 1 + size);
    if (!new_block)
    {
        list_prepend (&allocator->blocks, &old_block->link);
        return NULL;
    }
    else
    {
        list_prepend (&allocator->blocks, &new_block->link);
        return new_block->data;
    }
}

void
allocator_free (allocator_t *allocator, void *mem)
{
    block_t *block = GET_BLOCK (mem);

    list_unlink (&block->link);

    free (block);
}

void
allocator_fini (allocator_t *allocator)
{
    while (!list_is_empty (&allocator->blocks))
    {
        block_t *block = CONTAINER_OF (block_t, link, allocator->blocks.head);

        list_unlink (&block->link);

        free (block);
    }
}