shithub: lwext4

ref: a3d928e3777ab612ead4b903b4916558bffb040b
dir: /lwext4/ext4_bitmap.c/

/*
 * Copyright (c) 2013 Grzegorz Kostka (kostka.grzegorz@gmail.com)
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup lwext4
 * @{
 */
/**
 * @file  ext4_bitmap.c
 * @brief Block/inode bitmap allocator.
 */

#include <ext4_config.h>
#include <ext4_bitmap.h>

#include <ext4_errno.h>


void ext4_bmap_bits_free(uint8_t *bmap, uint32_t sbit, uint32_t bcnt)
{
    uint32_t i = sbit;

    while(i & 7){

        if(!bcnt)
            return;

        ext4_bmap_bit_clr(bmap, i);

        bcnt--;
        i++;
    }
    sbit  = i;
    bmap += (sbit >> 3);

    while(bcnt >= 32){
        *(uint32_t *)bmap = 0;
        bmap += 4;
        bcnt -= 32;
        sbit += 32;
    }

    while(bcnt >= 16){
        *(uint16_t *)bmap = 0;
        bmap += 2;
        bcnt -= 16;
        sbit += 16;
    }

    while(bcnt >= 8){
        *bmap = 0;
        bmap += 1;
        bcnt -= 8;
        sbit += 8;
    }

    for (i = 0; i < bcnt; ++i) {
        ext4_bmap_bit_clr(bmap, i);
    }
}



int ext4_bmap_bit_find_clr(uint8_t *bmap, uint32_t sbit, uint32_t ebit,
    uint32_t *bit_id)
{
    uint32_t i;
    uint32_t bcnt = ebit - sbit;

    i = sbit;

    while(i & 7){

        if(!bcnt)
            return ENOSPC;

        if(ext4_bmap_is_bit_clr(bmap, i)){
            *bit_id = sbit;
            return EOK;
        }

        i++;
        bcnt--;
    }

    sbit  = i;
    bmap += (sbit >> 3);


    while(bcnt >= 32){
        if(*(uint32_t *)bmap != 0xFFFFFFFF)
            goto finish_it;

        bmap += 4;
        bcnt -= 32;
        sbit += 32;
    }

    while(bcnt >= 16){
        if(*(uint16_t *)bmap != 0xFFFF)
            goto finish_it;

        bmap += 2;
        bcnt -= 16;
        sbit += 16;
    }

    finish_it:
    while(bcnt >= 8){
        if(*bmap != 0xFF){
            for (i = 0; i < 8; ++i) {
                if(ext4_bmap_is_bit_clr(bmap, i)){
                    *bit_id = sbit + i;
                    return EOK;
                }
            }
        }

        bmap += 1;
        bcnt -= 8;
        sbit += 8;
    }

    for (i = 0; i < bcnt; ++i) {
        if(ext4_bmap_is_bit_clr(bmap, i)){
            *bit_id = sbit + i;
            return EOK;
        }
    }

    return ENOSPC;
}

/**
 * @}
 */