/*
 * Yet Another Malloc
 * ya_freelist.h
 */

/* Block layout:
 *
 * -2     -1     0                               size-4 size-3
 * +------+------+-------- - - - - - - - --------+------+------+
 * | prev | size | data...                       | size | next |
 * +------+------+-------- - - - - - - - --------+------+------+
 *
 */

#ifndef YA_FREELIST_H
#define YA_FREELIST_H

/*----------*/
/* Includes */
/*----------*/

#include <stdint.h> // for intptr_t

#include "ya_block.h"
#include "ya_debug.h"

/*---------*/
/* Inlines */
/*---------*/

static inline intptr_t *fl_prev(intptr_t *block) {
    return (intptr_t *) block[-2];
}

static inline intptr_t *fl_next(intptr_t *block) {
    return (intptr_t *) block[block_size(block)-3];
}

static inline void fl_set_prev(intptr_t *block, intptr_t *prev) {
    block[-2] = (intptr_t) prev;   
}

static inline void fl_set_next(intptr_t *block, intptr_t *next) {
    block[block_size(block)-3] = (intptr_t) next;
}

/*--------------*/
/* Declarations */
/*--------------*/

#ifdef YA_DEBUG

/* Prints debug information about the free list. */
void fl_debug_print();

/* Checks the free list for consistency.
 * Returns -1 on error, the total number of free blocks otherwise. */
int fl_check();

#endif

/* Splices the allocated block out of the free list. */
void fl_alloc(intptr_t *block);

/* Adds the freed block to the appropriate place in free list. */
void fl_free(intptr_t *block);

/* Returns the first block in the free list at min_size words long.
 * Returns NULL if no adequate block is found. Does not grow the heap. */
intptr_t *fl_find(intptr_t min_size);

/* Mends the free list after a free block has just been split into two blocks,
 * block and new_next. */
void fl_mend_split(intptr_t *block, intptr_t *new_next);

void fl_join_prev(intptr_t *block);

void fl_join_next(intptr_t *block);

void fl_join(intptr_t *block);

/* Returns a pointer to the first free block. */
intptr_t *fl_get_start();

/* Returns a pointer to the last free block. */
intptr_t *fl_get_end();

#endif