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/*

    dos.c -- provides simple access to FAT (dos) partitions

    Copyright (C) 2002 Richard Herveille, rherveille@opencores.org

    This file is part of OpenRISC 1000 Reference Platform Monitor (ORPmon)

    This program is free software; you can redistribute it and/or modify

    it under the terms of the GNU General Public License as published by

    the Free Software Foundation; either version 2 of the License, or

    (at your option) any later version

    This program is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of

    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License

    along with this program; if not, write to the Free Software

    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

//#include "common.h"

#include <stddef.h>

#include <string.h>

#include "dos.h"

#include "ata.h"

/*

  D O S _ O P E N

*/

int dos_open(struct dosparam *params)

{

        int error, start_sector, partition;

        unsigned char buf[512];

        struct inode *inode = &params->inode;

        struct file *filp = &params->filp;

        struct request *request = &params->request;

        if ((error = ata_open(inode, filp)))

                return error;

        /* device opened, read MBR                                          */

        request->cmd = READ;

        request->sector = 0;

        request->nr_sectors = 1;

        request->buffer = buf;

        /* skip bootload (446) bytes                                        */

        /* currently only support the first partition (partition 4)         */

        /* This is OK, because CompactFLASH devices only have 1 partition   */

        if ((error = ata_request(inode, filp, request)))

                return error;

        partition = 0;           /* first partition                                */

        partition *= 16;        /* 16 bytes per partition table                   */

        partition += 446;       /* skip bootloader, go to partition table         */

        start_sector = buf[partition + 11] << 24 |

            buf[partition + 10] << 16 |

            buf[partition + 9] << 8 | buf[partition + 8];

        /* device opened, read boot-sector                                  */

        request->cmd = READ;

        request->sector = start_sector;

        request->nr_sectors = 1;

        request->buffer = buf;

        if ((error = ata_request(inode, filp, request)))

                return error;

        /* get the necessary data from the boot-sector                      */

        params->bytes_per_sector = (buf[12] << 8) | buf[11];

        params->fats = buf[16];

        params->sectors_per_fat = (buf[23] << 8) | buf[22];

        params->root_entries = (buf[18] << 8) | buf[17];

        params->sectors_per_cluster = buf[13];

        /* set start of current directory to start of root-directory        */

        params->ssector =

            start_sector + params->fats * params->sectors_per_fat + 1;

        /* set current sector to start of root-directory                    */

        params->csector = params->ssector;

        /* set start-entry number                                           */

        params->sentry = 0;

        return 0;

}

/*

  D O S _ R E L E A S E

*/

int dos_release(struct dosparam *params)

{

        return 0;

}

/*

  D O S _ N A M E C M P

*/

int dos_namecmp(const char *sname, const char *name, const char *ext)

{

        char fname[9], fext[4], *p;

        /* filename :                                                       */

        /* copy the filename                                                */

        strncpy(fname, sname, 8);

        /* check if we copied the '.' already, if so terminate string       */

        if ((p = strchr(fname, '.')))

                *p = '\0';

        /* fill remaining chars with ' '                                    */

        strncat(fname, "        ", 8 - strlen(fname));

        fname[9] = '\0';

        /* file-extension                                                   */

        /* search for the '.' in the filename                               */

        if ((p = strchr(sname, '.')))

                strncpy(fext, p, 3);

        else

                fext[0] = fext[1] = fext[2] = ' ';

        fext[4] = '\0';

        return (strcmp(fname, name) && strcmp(fext, ext));

}

/*

  D O S _ D I R _ F I N D _ E N T R Y

*/

struct dos_dir_entry *dos_dir_find_entry(struct dosparam *params,

                                         const char *name)

{

        struct dos_dir_entry *entry;

        unsigned long entry_no = 0;

        /* go to start of current directory                                 */

        if (params->csector != params->ssector)

                dos_dir_cluster_reset(params);

        /* search for the requested entry                                   */

        while ((entry = dos_dir_get_entry(params, entry_no))

               && dos_namecmp(name, entry->name, entry->ext))

                entry_no++;

        return entry;

}

/*

  D O S _ D I R _ G E T _ E N T R Y

*/

struct dos_dir_entry *dos_dir_get_entry(struct dosparam *params,

                                        unsigned long entry)

{

        char *buf = params->cbuf;

        if (entry < params->sentry)

                buf = dos_dir_cluster_reset(params);

        while (entry >= (params->sentry + entries_per_cluster(params)))

                if (!(buf = dos_dir_cluster_read_nxt(params)))

                        return NULL;

        return (struct dos_dir_entry *)(buf +

                                        ((entry -

                                          params->sentry) *

                                         sizeof(struct dos_dir_entry)));

}

/*

  D O S _ R E A D _ C L U S T E R

*/

char *dos_read_cluster(struct dosparam *params, unsigned long ssector)

{

        int error;

        struct inode *inode = &params->inode;

        struct file *filp = &params->filp;

        struct request *request = &params->request;

        request->cmd = READ;

        request->sector = ssector;

        request->nr_sectors = params->sectors_per_cluster;

        request->buffer = params->cbuf;

        if ((error = ata_request(inode, filp, request)))

                return NULL;

        params->csector = ssector;

        return params->cbuf;

}

/*

  D O S _ D I R _ C L U S T E R _ R E A D _ N X T

*/

char *dos_dir_cluster_read_nxt(struct dosparam *params)

{

        char *p;

        unsigned long nxt_cluster_start;

        /* TODO: add FAT lookup */

        nxt_cluster_start = params->csector + params->sectors_per_cluster;

        if (!(p = dos_read_cluster(params, nxt_cluster_start)))

                return NULL;

        params->sentry += entries_per_cluster(params);

        return p;

}

/*

  D O S _ D I R _ C L U S T E R _ R E S E T

*/

char *dos_dir_cluster_reset(struct dosparam *params)

{

        params->sentry = 0;

        return dos_read_cluster(params, params->ssector);

}