2.3-InternetRadio/nutos/nut/fs/phat32.c

/*
 * Copyright (C) 2005 by egnite Software GmbH. All rights reserved.
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 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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/*!
 * \file fs/phat32.c
 * \brief PHAT32 specific routines.
 *
 * \verbatim
 *
 * $Log$
 * Revision 1.6  2008/08/11 06:59:42  haraldkipp
 * BSD types replaced by stdint types (feature request #1282721).
 *
 * Revision 1.5  2006/02/23 15:45:21  haraldkipp
 * PHAT file system now supports configurable number of sector buffers.
 * This dramatically increased write rates of no-name cards.
 * AVR compile errors corrected.
 *
 * Revision 1.4  2006/01/23 19:52:10  haraldkipp
 * Added required typecasts before left shift.
 *
 * Revision 1.3  2006/01/23 17:33:47  haraldkipp
 * Avoid memory alignment errors.
 *
 * Revision 1.2  2006/01/22 17:43:46  haraldkipp
 * Bugfix. Deleting files sometimes corrupted a volume.
 *
 * Revision 1.1  2006/01/05 16:31:22  haraldkipp
 * First check-in.
 *
 *
 * \endverbatim
 */

#include <errno.h>

#include <fs/phatfs.h>
#include <fs/phatvol.h>
#include <fs/phatio.h>

/*!
 * \addtogroup xgPhat32
 */
/*@{*/

/*!
  * \brief Counts the number of free clusters in a fat32 volume, fast version.
  *
  * \param dev Specifies the file system device.
  *
  * \return The number of free clusters.
  */
uint32_t Phat32FreeClusters(NUTDEVICE * dev)
{
    PHATVOL *vol = (PHATVOL *) dev->dev_dcb;
    uint32_t rc = 0;
    uint32_t clust;
    uint32_t clustlast;
    uint32_t pos = -4;
    uint32_t sect;
    int sbn;
    uint8_t * sdata;

    /* Do not seek beyond the end of the chain. */
    clustlast = vol->vol_last_clust;
    if (clustlast >= (PHATEOC & PHAT32CMASK)) {
        clustlast = (PHATEOC & PHAT32CMASK) -1;
    }

    sect = vol->vol_tab_sect[0];
    sbn = PhatSectorLoad(dev, sect);
    if (sbn >= 0) {
        sdata = vol->vol_buf[sbn].sect_data;
        for (clust = 0; clust < clustlast; clust++) {
            pos += 4;
            /* Load the sector that contains the table entry. */
            if (pos >= vol->vol_sectsz) {
                PhatSectorBufferRelease(dev, sbn);
                pos = 0;
                sect++;
                sbn = PhatSectorLoad(dev, sect);
                if (sbn < 0) {
                    break;
                }
                sdata = vol->vol_buf[sbn].sect_data;
            }
            /* Check if the 32 bit link value is zero */
            if ((sdata[pos] | sdata[pos + 1] | sdata[pos + 2] | sdata[pos + 3]) == 0) {
                rc++;
            }
        }
        PhatSectorBufferRelease(dev, sbn);
    }
    return rc;
}

/*!
 * \brief Calculate table location of a specified cluster.
 *
 * \param vol    Mounted volume.
 * \param clust  Cluster number of the entry to locate.
 * \param tabnum Number of the table.
 * \param sect   Pointer to the variable that receives the sector of the
 *               table entry.
 * \param pos    Pointer to the variable that receives position within
 *               the sector.
 */
static void PhatTableLoc(PHATVOL * vol, uint32_t clust, int tabnum, uint32_t * sect, uint32_t * pos)
{
    uint32_t tabpos = clust * 4;

    *sect = vol->vol_tab_sect[tabnum] + tabpos / vol->vol_sectsz;
    *pos = tabpos % vol->vol_sectsz;
}

/*!
 * \brief Get link value of a specified cluster.
 *
 * \param dev   Specifies the file system device.
 * \param clust Get the link of this cluster.
 * \param link  Pointer to a variable which will receive the link.
 *
 * \return 0 on success or -1 on failure.
 */
int Phat32GetClusterLink(NUTDEVICE * dev, uint32_t clust, uint32_t * link)
{
    uint32_t sect, pos;
    int sbn;
    PHATVOL *vol = (PHATVOL *) dev->dev_dcb;

    /* Do not seek beyond the end of the chain. */
    if (clust >= (PHATEOC & PHAT32CMASK)) {
        return -1;
    }

    /* Load the sector that contains the table entry. */
    PhatTableLoc(vol, clust, 0, &sect, &pos);
    if ((sbn = PhatSectorLoad(dev, sect)) < 0) {
        return -1;
    }

    /* Get the 32 bit link value. */
    *link = vol->vol_buf[sbn].sect_data[pos];
    *link += (uint32_t)(vol->vol_buf[sbn].sect_data[pos + 1]) << 8;
    *link += (uint32_t)(vol->vol_buf[sbn].sect_data[pos + 2]) << 16;
    *link += (uint32_t)(vol->vol_buf[sbn].sect_data[pos + 3]) << 24;
    PhatSectorBufferRelease(dev, sbn);

    return 0;
}

/*!
 * \brief Set link value of a specified cluster.
 *
 * \param dev   Specifies the file system device.
 * \param clust This cluster will be linked.
 * \param link  Link to this cluster.
 *
 * \return 0 on success or -1 on failure.
 */
int Phat32SetClusterLink(NUTDEVICE * dev, uint32_t clust, uint32_t link)
{
    int tabnum;
    uint32_t sect;
    uint32_t pos;
    int sbn;
    PHATVOL *vol = (PHATVOL *) dev->dev_dcb;

    for (tabnum = 0; tabnum < 2 && vol->vol_tab_sect[tabnum]; tabnum++) {
        link &= PHAT32CMASK;

        PhatTableLoc(vol, clust, tabnum, &sect, &pos);
        if ((sbn = PhatSectorLoad(dev, sect)) < 0) {
            return -1;
        }
        vol->vol_buf[sbn].sect_data[pos] = (uint8_t) link;
        vol->vol_buf[sbn].sect_data[pos + 1] = (uint8_t) (link >> 8);
        vol->vol_buf[sbn].sect_data[pos + 2] = (uint8_t) (link >> 16);
        vol->vol_buf[sbn].sect_data[pos + 3] = (uint8_t) (link >> 24);
        vol->vol_buf[sbn].sect_dirty = 1;
        PhatSectorBufferRelease(dev, sbn);
    }
    return 0;
}

/*!
 * \brief Release a cluster chain.
 *
 * \param dev   Specifies the file system device.
 * \param first First cluster of the chain to release.
 *
 * \return 0 on success or -1 on failure.
 */
int Phat32ReleaseChain(NUTDEVICE * dev, uint32_t first)
{
    uint32_t next;
    PHATVOL *vol = (PHATVOL *) dev->dev_dcb;

    while (first < (PHATEOC & PHAT32CMASK)) {
        if (Phat32GetClusterLink(dev, first, &next)) {
            /* Read error. */
            return -1;
        }
        if (next < 2) {
            /* Incomplete chain, should not happen. */
            break;
        }
        if (Phat32SetClusterLink(dev, first, 0)) {
            /* Write error. */
            return -1;
        }
        vol->vol_numfree++;
        first = next;
    }
    return 0;
}

/*@}*/