/*
 * Copyright 2009 Colin Günther, coling@gmx.de
 * Copyright 2018, Haiku, Inc.
 * All rights reserved. Distributed under the terms of the MIT license.
 */


/*! Implementation of a number allocator.*/


extern "C" {
#include <sys/mutex.h>

#include "unit.h"
}

#include <stdlib.h>
#include <util/RadixBitmap.h>


#define ID_STORE_FULL -1


extern struct mtx gIdStoreLock;


struct unrhdr*
new_unrhdr(int low, int high, struct mtx* mutex)
{
        struct unrhdr* idStore;
        uint32 maxIdCount = high - low + 1;

        KASSERT(low <= high,
                ("ID-Store: use error: %s(%u, %u)", __func__, low, high));

        idStore = (unrhdr*)malloc(sizeof *idStore);
        if (idStore == NULL)
                return NULL;

        idStore->idBuffer = radix_bitmap_create(maxIdCount);
        if (idStore->idBuffer == NULL) {
                free(idStore);
                return NULL;
        }

        if (mutex)
                idStore->storeMutex = mutex;
        else
                idStore->storeMutex = &gIdStoreLock;

        idStore->idBias = low;

        return idStore;
}


void
delete_unrhdr(struct unrhdr* idStore)
{
        KASSERT(idStore != NULL,
                ("ID-Store: %s: NULL pointer as argument.", __func__));

        mtx_lock(idStore->storeMutex);

        radix_bitmap_destroy(idStore->idBuffer);
        mtx_unlock(idStore->storeMutex);

        free(idStore);
        idStore = NULL;
}


int
alloc_unr(struct unrhdr* idStore)
{
        int id;

        KASSERT(idStore != NULL,
                ("ID-Store: %s: NULL pointer as argument.", __func__));

        mtx_lock(idStore->storeMutex);

        radix_slot_t slotIndex;
        id = ID_STORE_FULL;

        slotIndex = radix_bitmap_alloc(idStore->idBuffer, 1);
        if (slotIndex != RADIX_SLOT_NONE)
                id = slotIndex + idStore->idBias;

        mtx_unlock(idStore->storeMutex);

        return id;
}


void
free_unr(struct unrhdr* idStore, u_int identity)
{
        KASSERT(idStore != NULL,
                ("ID-Store: %s: NULL pointer as argument.", __func__));

        mtx_lock(idStore->storeMutex);

        uint32 slotIndex = (int32)identity - idStore->idBias;
        KASSERT(slotIndex >= 0, ("ID-Store: %s(%p, %u): second "
                "parameter is not in interval.", __func__, idStore, identity));

        radix_bitmap_dealloc(idStore->idBuffer, slotIndex, 1);

        mtx_unlock(idStore->storeMutex);
}