/*
 * Copyright (c) 2011 Intel Corporation. All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
 * IN NO EVENT SHALL PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR
 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors:
 *    Waldo Bastian <waldo.bastian@intel.com>
 *
 */

#include "object_heap.h"

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

#include "psb_def.h"

#define LAST_FREE    -1
#define ALLOCATED    -2
#define SUSPENDED    -3

/*
 * Expands the heap
 * Return 0 on success, -1 on error
 */
static int object_heap_expand(object_heap_p heap)
{
    int i;
    int malloc_error = FALSE;
    object_base_p *new_heap_index;
    int next_free;
    int new_heap_size = heap->heap_size + heap->heap_increment;

    new_heap_index = (object_base_p *) realloc(heap->heap_index, new_heap_size * sizeof(object_base_p));
    if (NULL == new_heap_index) {
        return -1; /* Out of memory */
    }
    heap->heap_index = new_heap_index;
    next_free = heap->next_free;
    for (i = new_heap_size; i-- > heap->heap_size;) {
        object_base_p obj = (object_base_p) calloc(1, heap->object_size);
        heap->heap_index[i] = obj;
        if (NULL == obj) {
            malloc_error = TRUE;
            continue; /* Clean up after the loop is completely done */
        }
        obj->id = i + heap->id_offset;
        obj->next_free = next_free;
        next_free = i;
    }

    if (malloc_error) {
        /* Clean up the mess */
        for (i = new_heap_size; i-- > heap->heap_size;) {
            if (heap->heap_index[i]) {
                free(heap->heap_index[i]);
            }
        }
        /* heap->heap_index is left as is */
        return -1; /* Out of memory */
    }
    heap->next_free = next_free;
    heap->heap_size = new_heap_size;
    return 0; /* Success */
}

/*
 * Return 0 on success, -1 on error
 */
int object_heap_init(object_heap_p heap, int object_size, int id_offset)
{
    heap->object_size = object_size;
    heap->id_offset = id_offset & OBJECT_HEAP_OFFSET_MASK;
    heap->heap_size = 0;
    heap->heap_increment = 16;
    heap->heap_index = NULL;
    heap->next_free = LAST_FREE;
    return object_heap_expand(heap);
}

/*
 * Allocates an object
 * Returns the object ID on success, returns -1 on error
 */
int object_heap_allocate(object_heap_p heap)
{
    object_base_p obj;
    if (LAST_FREE == heap->next_free) {
        if (-1 == object_heap_expand(heap)) {
            return -1; /* Out of memory */
        }
    }
    ASSERT(heap->next_free >= 0);

    obj = heap->heap_index[heap->next_free];
    heap->next_free = obj->next_free;
    obj->next_free = ALLOCATED;
    return obj->id;
}

/*
 * Lookup an object by object ID
 * Returns a pointer to the object on success, returns NULL on error
 */
object_base_p object_heap_lookup(object_heap_p heap, int id)
{
    object_base_p obj;
    if ((id < heap->id_offset) || (id > (heap->heap_size + heap->id_offset))) {
        return NULL;
    }
    id &= OBJECT_HEAP_ID_MASK;
    obj = heap->heap_index[id];

    /* Check if the object has in fact been allocated */
    if (obj->next_free != ALLOCATED) {
        return NULL;
    }
    return obj;
}

/*
 * Iterate over all objects in the heap.
 * Returns a pointer to the first object on the heap, returns NULL if heap is empty.
 */
object_base_p object_heap_first(object_heap_p heap, object_heap_iterator *iter)
{
    *iter = -1;
    return object_heap_next(heap, iter);
}

/*
 * Iterate over all objects in the heap.
 * Returns a pointer to the next object on the heap, returns NULL if heap is empty.
 */
object_base_p object_heap_next(object_heap_p heap, object_heap_iterator *iter)
{
    object_base_p obj;
    int i = *iter + 1;
    while (i < heap->heap_size) {
        obj = heap->heap_index[i];
        if ((obj->next_free == ALLOCATED) || (obj->next_free == SUSPENDED)) {
            *iter = i;
            return obj;
        }
        i++;
    }
    *iter = i;
    return NULL;
}



/*
 * Frees an object
 */
void object_heap_free(object_heap_p heap, object_base_p obj)
{
    /* Don't complain about NULL pointers */
    if (NULL != obj) {
        /* Check if the object has in fact been allocated */
        ASSERT((obj->next_free == ALLOCATED) || (obj->next_free == SUSPENDED));

        obj->next_free = heap->next_free;
        heap->next_free = obj->id & OBJECT_HEAP_ID_MASK;
    }
}

/*
 * Destroys a heap, the heap must be empty.
 */
void object_heap_destroy(object_heap_p heap)
{
    object_base_p obj;
    int i;
    for (i = 0; i < heap->heap_size; i++) {
        /* Check if object is not still allocated */
        obj = heap->heap_index[i];
        ASSERT(obj->next_free != ALLOCATED);
        ASSERT(obj->next_free != SUSPENDED);
        /* Free object itself */
        free(obj);
    }
    free(heap->heap_index);
    heap->heap_size = 0;
    heap->heap_index = NULL;
    heap->next_free = LAST_FREE;
}

/*
 * Suspend an object
 * Suspended objects can not be looked up
 */
void object_heap_suspend_object(object_base_p obj, int suspend)
{
    if (suspend) {
        ASSERT(obj->next_free == ALLOCATED);
        obj->next_free = SUSPENDED;
    } else {
        ASSERT(obj->next_free == SUSPENDED);
        obj->next_free = ALLOCATED;
    }
}