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nuttx-bb/nuttx/fs/fat/fs_configfat.c

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/****************************************************************************
* fs/fat/fs_configfat.c
*
* Copyright (C) 2008 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "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
* COPYRIGHT OWNER OR CONTRIBUTORS 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <string.h>
#include <debug.h>
#include <errno.h>
#include <nuttx/fs.h>
#include <nuttx/fat.h>
#include <nuttx/mkfatfs.h>
#include "fs_internal.h"
#include "fs_fat32.h"
#include "fs_mkfatfs.h"
/****************************************************************************
* Definitions
****************************************************************************/
#define NDX12 0
#define NDX16 1
#define NDX32 2
#define fatconfig12 fatconfig[NDX12]
#define fatconfig16 fatconfig[NDX16]
#define fatconfig32 fatconfig[NDX32]
/* JMP rel8 and NOP opcodes */
#define OPCODE_JMP_REL8 0xeb
#define OPCODE_NOP 0x90
#define BOOTCODE_MSGOFFSET 29
/****************************************************************************
* Private Types
****************************************************************************/
struct fat_config_s
{
uint32 fc_navailsects; /* The number of available sectors */
uint32 fc_nfatsects; /* The number of sectors in one FAT */
uint32 fc_nclusters; /* The number of clusters in the filesystem */
uint32 fc_rsvdseccount; /* The number of reserved sectors */
};
/****************************************************************************
* Private Data
****************************************************************************/
/* Reverse engineered, generic boot message logic for non-bootable disk.
* Message begins at offset 29; Sector relative offset must be poked into
* offset 3.
*/
static ubyte g_bootcodeblob[] =
{
0x0e, 0x1f, 0xbe, 0x00, 0x7c, 0xac, 0x22, 0xc0, 0x74, 0x0b, 0x56,
0xb4, 0x0e, 0xbb, 0x07, 0x00, 0xcd, 0x10, 0x5e, 0xeb, 0xf0, 0x32,
0xe4, 0xcd, 0x16, 0xcd, 0x19, 0xeb, 0xfe, 0x54, 0x68, 0x69, 0x73,
0x20, 0x69, 0x73, 0x20, 0x6e, 0x6f, 0x74, 0x20, 0x61, 0x20, 0x62,
0x6f, 0x6f, 0x74, 0x61, 0x62, 0x6c, 0x65, 0x20, 0x64, 0x69, 0x73,
0x6b, 0x2e, 0x20, 0x20, 0x50, 0x6c, 0x65, 0x61, 0x73, 0x65, 0x20,
0x69, 0x6e, 0x73, 0x65, 0x72, 0x74, 0x20, 0x61, 0x20, 0x62, 0x6f,
0x6f, 0x74, 0x61, 0x62, 0x6c, 0x65, 0x20, 0x66, 0x6c, 0x6f, 0x70,
0x70, 0x79, 0x20, 0x61, 0x6e, 0x64, 0x0d, 0x0a, 0x70, 0x72, 0x65,
0x73, 0x73, 0x20, 0x61, 0x6e, 0x79, 0x20, 0x6b, 0x65, 0x79, 0x20,
0x74, 0x6f, 0x20, 0x74, 0x72, 0x79, 0x20, 0x61, 0x67, 0x61, 0x69,
0x6e, 0x20, 0x2e, 0x2e, 0x2e, 0x0d, 0x0a, 0x00
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: mkfatfs_nfatsect12
*
* Description:
* Calculate the number of sectors need for one fat in a FAT12 file system.
*
* Input:
* fmt - Caller specified format parameters
* var - Other format parameters that are not caller specifiable. (Most
* set by mkfatfs_configfatfs()).
* navailsects - The number of sectors available for both FAT and data.
* This is a precalculated value equal to the total number of sectors
* minus the number of root directory sectors and minus the number of
* reserved sectors.
*
* Return:
* 0: That calculation would have overflowed
* >0: The size of one FAT in sectors.
*
****************************************************************************/
static inline uint32
mkfatfs_nfatsect12(FAR struct fat_format_s *fmt, FAR struct fat_var_s *var,
uint32 navailsects)
{
#ifdef CONFIG_HAVE_LONG_LONG
uint64 denom;
uint64 numer;
#else
uint32 denom;
uint32 numer;
#endif
/* For FAT12, the cluster number is held in a 12-bit number or 1.5 bytes per
* cluster reference. So each FAT sector will hold sectorsize/1.5 cluster
* references (except for the first sector of each FAT which has two reserved
* 12-bit values). And the total number of FAT sectors needed is:
*
* nfatsects = (1.5 * (ndataclust + 2) / sectorsize)
*
* where:
*
* ndataclust = ndatasect / clustsize
* nvailsects = nfatsects + ndatasect
*
* The solution to this set of linear equations is:
*
* nfatsects = (3 * navailsects + 6 * clustersize) /
* (3 * nfats + 2 * sectorsize * clustersize)
*
* The numerator would overflow uint32 if:
*
* 3 * navailsects + 6 * clustersize > 0xffffffff
*
* Or
*
* navailsects > 0x55555555 - 2 * clustersize
*/
#ifndef CONFIG_HAVE_LONG_LONG
if (navailsects <= (0x55555555 - (1 << (fmt->ff_clustshift + 1))))
{
#endif
denom = (fmt->ff_nfats << 1) + fmt->ff_nfats
+ (var->fv_sectorsize << (fmt->ff_clustshift + 1));
numer = (navailsects << 1) + navailsects
+ (1 << (fmt->ff_clustshift + 2)) + (1 << (fmt->ff_clustshift + 1));
return (uint32)((numer + denom - 1) / denom);
#ifndef CONFIG_HAVE_LONG_LONG
}
else
{
return 0;
}
#endif
}
/****************************************************************************
* Name: mkfatfs_nfatsect16
*
* Description:
* Calculate the number of sectors need for one fat in a FAT16 file system.
*
* Input:
* fmt - Caller specified format parameters
* var - Other format parameters that are not caller specifiable. (Most
* set by mkfatfs_configfatfs()).
* navailsects - The number of sectors available for both FAT and data.
* This is a precalculated value equal to the total number of sectors
* minus the number of root directory sectors and minus the number of
* reserved sectors.
*
* Return:
* The size of one FAT in sectors.
*
****************************************************************************/
static inline uint32
mkfatfs_nfatsect16(FAR struct fat_format_s *fmt, FAR struct fat_var_s *var,
uint32 navailsects)
{
#ifdef CONFIG_HAVE_LONG_LONG
uint64 denom;
uint64 numer;
#else
uint32 denom;
uint32 numer;
#endif
/* For FAT16, the cluster number is held in a 16-bit number or 2 bytes per
* cluster reference. So each FAT sector will hold sectorsize/2 cluster
* references (except for the first sector of each FAT which has two reserved
* 16-bit values). And the total number of FAT sectors needed is:
*
* nfatsects = (2 * (ndataclust + 2) / sectorsize)
*
* where:
*
* ndataclust = ndatasect / clustsize
* nvailsects = nfatsects + ndatasect
*
* The solution to this set of linear equations is:
*
* nfatsects = (navailsects + 2 * clustersize) /
* (nfats + sectorsize * clustersize / 2)
*
* Overflow in the calculation of the numerator could occur if:
*
* navailsects > 0xffffffff - 2 * clustersize
*/
if (fmt->ff_clustshift == 0)
{
denom = fmt->ff_nfats + (var->fv_sectorsize >> 1);
numer = navailsects + 2;
}
else
{
denom = fmt->ff_nfats + (var->fv_sectorsize << (fmt->ff_clustshift - 1));
numer = navailsects + (1 << (fmt->ff_clustshift + 1));
}
return (uint32)((numer + denom - 1) / denom);
}
/****************************************************************************
* Name: mkfatfs_nfatsect32
*
* Description:
* Calculate the number of sectors need for one fat in a FAT32 file system.
*
* Input:
* fmt - Caller specified format parameters
* var - Other format parameters that are not caller specifiable. (Most
* set by mkfatfs_configfatfs()).
* navailsects - The number of sectors available for both FAT and data.
* This is a precalculated value equal to the total number of sectors
* minus the number of root directory sectors and minus the number of
* reserved sectors.
*
* Return:
* The size of one FAT in sectors.
*
****************************************************************************/
static inline uint32
mkfatfs_nfatsect32(FAR struct fat_format_s *fmt, FAR struct fat_var_s *var,
uint32 navailsects)
{
#ifdef CONFIG_HAVE_LONG_LONG
uint64 denom;
uint64 numer;
#else
uint32 denom;
uint32 numer;
#endif
/* For FAT32, the cluster number is held in a 32-bit number or 4 bytes per
* cluster reference. So each FAT sector will hold sectorsize/4 cluster
* references (except for the first sector of each FAT which has three reserved
* 32-bit values). And the total number of FAT sectors needed is:
*
* nfatsects = (4 * (ndataclust + 3) / sectorsize)
*
* where:
*
* ndataclust = ndatasect / clustsize
* nvailsects = nfatsects + ndatasect
*
* The solution to this set of linear equations is:
*
* nfatsects = (navailsects + 3 * clustersize) /
* (nfats + sectorsize * clustersize / 4)
*
* Overflow in the 32-bit calculation of the numerator could occur if:
*
* navailsects > 0xffffffff - 3 * clustersize
*/
if (fmt->ff_clustshift == 0)
{
denom = fmt->ff_nfats + (var->fv_sectorsize >> 2);
numer = navailsects + 3;
}
else if (fmt->ff_clustshift == 1)
{
denom = fmt->ff_nfats + (var->fv_sectorsize >> 1);
numer = navailsects + 6;
}
else
{
denom = fmt->ff_nfats + (var->fv_sectorsize << (fmt->ff_clustshift - 2));
numer = navailsects + (1 << (fmt->ff_clustshift + 1)) + (1 << fmt->ff_clustshift);
}
return (uint32)((numer + denom - 1) / denom);
}
/****************************************************************************
* Name: mkfatfs_clustersearchlimits
*
* Description:
* Pick the starting and ending cluster size to use in the search for the
* the optimal cluster size.
*
* Input:
* fmt - Caller specified format parameters
* var - Other format parameters that are not caller specifiable. (Most
* set by mkfatfs_configfatfs()).
*
* Return:
* Starting cluster size is set in fmt->ff_clustshift; Final cluster
* size is the returned value.
*
****************************************************************************/
static inline ubyte
mkfatfs_clustersearchlimits(FAR struct fat_format_s *fmt, FAR struct fat_var_s *var)
{
ubyte mxclustshift;
/* Did the caller already pick the cluster size? If not, the clustshift value
* will be 0xff
*/
if (fmt->ff_clustshift == 0xff)
{
/* Pick a starting size based on the number of sectors on the device */
if (fmt->ff_nsectors < 2048)
{
/* 2k sectors, start wit 1 sector/cluster. */
fmt->ff_clustshift = 0;
}
else if (fmt->ff_nsectors < 4096)
{
/* 4k sectors, start with 2 sector/cluster. */
fmt->ff_clustshift = 1;
}
else if (fmt->ff_nsectors < 8192)
{
/* 8k sectors, start with 4 sector/cluster. */
fmt->ff_clustshift = 2;
}
else if (fmt->ff_nsectors < 16384)
{
/* 16k sectors, start with 8 sector/cluster. */
fmt->ff_clustshift = 3;
}
else if (fmt->ff_nsectors < 32768)
{
/* 32k sectors, start with 16 sector/cluster. */
fmt->ff_clustshift = 4;
}
else
{
/* Otherwise, 32 sector/cluster. */
fmt->ff_clustshift = 5;
}
/* Wherever the search starts, it will end with the maximum of
* 128 sectors per cluster
*/
mxclustshift = 7;
}
else
{
/* The caller has selected a cluster size. There will be no search!
* Just set the maximum to the caller specificed value.
*/
mxclustshift = fmt->ff_clustshift;
}
return mxclustshift;
}
/****************************************************************************
* Name: mkfatfs_try12
*
* Description:
* Try to define a FAT12 filesystem on the device using the candidate
* sectors per cluster
*
* Input:
* fmt - Caller specified format parameters
* var - Other format parameters that are not caller specifiable. (Most
* set by mkfatfs_configfatfs()).
* fatconfig - FAT12-specific configuration
*
* Return:
* Zero on success configuration of a FAT12 file system; negated errno
* on failure
*
****************************************************************************/
static inline int
mkfatfs_tryfat12(FAR struct fat_format_s *fmt, FAR struct fat_var_s *var,
FAR struct fat_config_s *config)
{
uint32 maxnclusters;
/* Calculate the number sectors in one FAT required to access all of the
* available sectors.
*/
config->fc_nfatsects = mkfatfs_nfatsect12(fmt, var, config->fc_navailsects);
if (config->fc_nfatsects > 0)
{
/* Calculate the number of clusters available given the number of available
* sectors and the number of those that will be used for FAT:
*/
config->fc_nclusters =
(config->fc_navailsects -
fmt->ff_nfats * config->fc_nfatsects) >> fmt->ff_clustshift;
/* Calculate the maximum number of clusters that could be supported by a
* FAT of this size.
*
* maxnclusters = nfatsects * sectorsize / 1.5 - 2
*/
maxnclusters = (config->fc_nfatsects >> (var->fv_sectshift + 1)) / 3;
if (maxnclusters > FAT_MAXCLUST12)
{
maxnclusters = FAT_MAXCLUST12;
}
fvdbg("nfatsects=%u nclusters=%u (max=%u)\n",
config->fc_nfatsects, config->fc_nclusters, maxnclusters);
/* Check if this number of clusters would overflow the maximum for
* FAT12 (remembering that two FAT cluster slots are reserved).
*/
if (config->fc_nclusters > maxnclusters - 2)
{
fvdbg("Too many clusters for FAT12\n");
return -ENFILE;
}
}
return 0;
}
/****************************************************************************
* Name: mkfatfs_try16
*
* Description:
* Try to define a FAT16 filesystem on the device using the candidate
* sectors per cluster
*
* Input:
* fmt - Caller specified format parameters
* var - Other format parameters that are not caller specifiable. (Most
* set by mkfatfs_configfatfs()).
* fatconfig - FAT16-specific configuration
*
* Return:
* Zero on success configuration of a FAT16 file system; negated errno
* on failure
*
****************************************************************************/
static inline int
mkfatfs_tryfat16(FAR struct fat_format_s *fmt, FAR struct fat_var_s *var,
FAR struct fat_config_s *config)
{
uint32 maxnclusters;
/* Calculate the number sectors in one FAT required to access all of the
* available sectors.
*/
config->fc_nfatsects = mkfatfs_nfatsect16(fmt, var, config->fc_navailsects);
if (config->fc_nfatsects > 0)
{
/* Calculate the number of clusters available given the number of available
* sectors and the number of those that will be used for FAT:
*/
config->fc_nclusters =
(config->fc_navailsects -
fmt->ff_nfats * config->fc_nfatsects) >> fmt->ff_clustshift;
/* Calculate the maximum number of clusters that could be supported by a
* FAT of this size.
*
* maxnclusters = nfatsects * sectorsize / 2 - 2
*/
maxnclusters = config->fc_nfatsects << (var->fv_sectorsize - 1);
if (maxnclusters > FAT_MAXCLUST16)
{
maxnclusters = FAT_MAXCLUST16;
}
fvdbg("nfatsects=%u nclusters=%u (min=%u max=%u)\n",
config->fc_nfatsects, config->fc_nclusters, FAT_MINCLUST16, maxnclusters);
/* Check if this number of clusters would overflow the maximum for
* FAT16 (remembering that two FAT cluster slots are reserved).
* Check the lower limit as well. The FAT12 is distinguished from FAT16
* by comparing the number of clusters on the device agains a known
* threshold. If a small FAT16 file system were created, then it would
* be confused as a FAT12 at mount time.
*/
if ((config->fc_nclusters > maxnclusters - 2) ||
(config->fc_nclusters < FAT_MINCLUST16))
{
fvdbg("Too few or too many clusters for FAT16\n");
return -ENFILE;
}
}
return 0;
}
/****************************************************************************
* Name: mkfatfs_try32
*
* Description:
* Try to define a FAT32 filesystem on the device using the candidate
* sectors per cluster
*
* Input:
* fmt - Caller specified format parameters
* var - Other format parameters that are not caller specifiable. (Most
* set by mkfatfs_configfatfs()).
* fatconfig - FAT32-specific configuration
*
* Return:
* Zero on success configuration of a FAT32 file system; negated errno
* on failure
*
****************************************************************************/
static inline int
mkfatfs_tryfat32(FAR struct fat_format_s *fmt, FAR struct fat_var_s *var,
FAR struct fat_config_s *config)
{
uint32 maxnclusters;
/* Calculate the number sectors in one FAT required to access all of the
* available sectors.
*/
config->fc_nfatsects = mkfatfs_nfatsect32(fmt, var, config->fc_navailsects);
if (config->fc_nfatsects > 0)
{
/* Calculate the number of clusters available given the number of available
* sectors and the number of those that will be used for FAT:
*/
config->fc_nclusters =
(config->fc_navailsects -
fmt->ff_nfats * config->fc_nfatsects) >> fmt->ff_clustshift;
/* Calculate the maximum number of clusters that could be supported by a
* FAT of this size.
*
* maxnclusters = nfatsects * sectorsize / 4 - 2
*/
maxnclusters = (config->fc_nfatsects >> (var->fv_sectshift - 2));
if (maxnclusters > FAT_MAXCLUST32)
{
maxnclusters = FAT_MAXCLUST32;
}
fvdbg("nfatsects=%u nclusters=%u (max=%u)\n",
config->fc_nfatsects, config->fc_nclusters, maxnclusters);
/* Check if this number of clusters would overflow the maximum for
* FAT32 (remembering that two FAT cluster slots are reserved).
*/
if ((config->fc_nclusters > maxnclusters - 3) ||
(config->fc_nclusters < FAT_MINCLUST32 && fmt->ff_fattype != 32))
{
fvdbg("Too few or too many clusters for FAT32\n");
return -ENFILE;
}
}
return 0;
}
/****************************************************************************
* Name: mkfatfs_selectfat
*
* Description:
* The cluster search has succeeded, select the specified FAT FS
*
* Input:
* fattype - The FAT size selected
* fmt - Caller specified format parameters
* var - Format parameters that are not caller specifiable.
*
* Return:
* None
*
****************************************************************************/
static inline void
mkfatfs_selectfat(int fattype, FAR struct fat_format_s *fmt,
FAR struct fat_var_s *var, FAR struct fat_config_s *config)
{
/* Return the appropriate information about the selected file system. */
fdbg("Selected FAT%d\n", fattype);
var->fv_fattype = fattype;
var->fv_nclusters = config->fc_nclusters;
var->fv_nfatsects = config->fc_nfatsects;
fmt->ff_rsvdseccount = config->fc_rsvdseccount;
}
/****************************************************************************
* Name: mkfatfs_clustersearch
*
* Description:
* Search to find the smallest (reasonable) cluster size for the FAT file
* system.
*
* Input:
* fmt - Caller specified format parameters
* var - Other format parameters that are not caller specifiable. (Most
* set by mkfatfs_configfatfs()).
*
* Return:
* Zero on success; negated errno on failure
*
****************************************************************************/
static inline int
mkfatfs_clustersearch(FAR struct fat_format_s *fmt, FAR struct fat_var_s *var)
{
struct fat_config_s fatconfig[3];
ubyte mxclustshift;
memset(fatconfig, 0, 3*sizeof(struct fat_config_s));
/* Select the reserved sector count for each FAT size */
if (fmt->ff_rsvdseccount)
{
fatconfig12.fc_rsvdseccount = fmt->ff_rsvdseccount;
fatconfig16.fc_rsvdseccount = fmt->ff_rsvdseccount;
if (fmt->ff_rsvdseccount < 2)
{
fvdbg("At least 2 reserved sectors needed by FAT32\n");
fatconfig32.fc_rsvdseccount = 2;
}
else
{
fatconfig32.fc_rsvdseccount = fmt->ff_rsvdseccount;
}
}
else
{
fatconfig12.fc_rsvdseccount = 1;
fatconfig16.fc_rsvdseccount = 1;
fatconfig32.fc_rsvdseccount = 32;
}
/* Determine the number of sectors needed by the root directory.
* This is a constant value, independent of cluster size for FAT12/16
*/
if (var->fv_fattype != 32)
{
/* Calculate the number of sectors reqired to contain the selected
* number of root directory entries. This value is save in the var
* structure but will be overwritten if FAT32 is selected. FAT32 uses
* a cluster chain for the root directory, so the concept of the number
* of root directory entries does not apply to FAT32
*/
var->fv_nrootdirsects =
((fmt->ff_rootdirentries << DIR_SHIFT) + var->fv_sectorsize - 1) >> var->fv_sectshift;
/* The number of data sectors available (includes the fat itself)
* This value is a constant for FAT12/16, but not FAT32 because the
* size of the root directory cluster changes
*/
fatconfig12.fc_navailsects =
fatconfig16.fc_navailsects =
fmt->ff_nsectors - var->fv_nrootdirsects - fatconfig12.fc_rsvdseccount;
}
/* Select an initial and terminal clustersize to use in the search (if these
* values were not provided by the caller)
*/
mxclustshift = mkfatfs_clustersearchlimits(fmt, var);
do
{
fvdbg("Configuring with %d sectors/cluster...\n", 1 << fmt->ff_clustshift);
/* Check if FAT12 has not been excluded */
if (var->fv_fattype == 0 || var->fv_fattype == 12)
{
/* Try to configure a FAT12 filesystem with this cluster size */
if (mkfatfs_tryfat12(fmt, var, &fatconfig12) != 0)
{
{
fvdbg("Cannot format FAT12 at %u sectors/cluster\n", 1 << fmt->ff_clustshift);
fatconfig12.fc_nfatsects = 0;
fatconfig12.fc_nclusters = 0;
}
}
}
/* Check if FAT16 has not been excluded */
if (var->fv_fattype == 0 || var->fv_fattype == 16)
{
/* Try to configure a FAT16 filesystem with this cluster size */
if (mkfatfs_tryfat16(fmt, var, &fatconfig16) != 0)
{
{
fvdbg("Cannot format FAT16 at %u sectors/cluster\n", 1 << fmt->ff_clustshift);
fatconfig16.fc_nfatsects = 0;
fatconfig16.fc_nclusters = 0;
}
}
}
/* If either FAT12 or 16 was configured at this sector/cluster setting,
* then finish the configuration and break out now
*/
if (fatconfig12.fc_nclusters || fatconfig16.fc_nclusters)
{
if ((!var->fv_fattype && fatconfig16.fc_nclusters > fatconfig12.fc_nclusters) ||
(var ->fv_fattype == 16))
{
/* The caller has selected FAT16 -OR- no FAT type has been selected, but
* the FAT16 selection has more clusters. Select FAT16.
*/
mkfatfs_selectfat(16, fmt, var, &fatconfig16);
}
else
{
/* The caller has selected FAT12 -OR- no FAT type has been selected, but
* the FAT12 selected has more clusters. Selected FAT12
*/
mkfatfs_selectfat(12, fmt, var, &fatconfig12);
}
return OK;
}
/* Check if FAT32 has not been excluded */
if (var->fv_fattype == 0 || var->fv_fattype == 32)
{
/* The number of data sectors available (includes the fat itself)
* This value is a constant with respect to cluster sizefor FAT12/16, but not FAT32
* because the size of the root directory cluster changes with cluster size.
*/
fatconfig32.fc_navailsects = fmt->ff_nsectors - (1 << fmt->ff_clustshift) - fatconfig32.fc_rsvdseccount;
/* Try to configure a FAT32 filesystem with this cluster size */
if (mkfatfs_tryfat32(fmt, var, &fatconfig32) != 0)
{
{
fvdbg("Cannot format FAT32 at %u sectors/cluster\n", 1 << fmt->ff_clustshift);
fatconfig32.fc_nfatsects = 0;
fatconfig32.fc_nclusters = 0;
}
}
else
{
/* Select FAT32 if we have not already done so */
mkfatfs_selectfat(32, fmt, var, &fatconfig32);
return OK;
}
}
/* Otherwise, bump up the sectors/cluster for the next time around the loop. */
fmt->ff_clustshift++;
}
while (fmt->ff_clustshift <= mxclustshift);
return -ENFILE;
}
/****************************************************************************
* Global Functions
****************************************************************************/
/****************************************************************************
* Name: mkfatfs_configfatfs
*
* Description:
* Based on the geometry of the block device and upon the caller-selected
* values, configure the FAT filesystem for the device.
*
* Input:
* fmt - Caller specified format parameters
* var - Holds disk geomtry data. Also, the location to return FAT
* configuration data
*
* Return:
* Zero on success; negated errno on failure
*
****************************************************************************/
int mkfatfs_configfatfs(FAR struct fat_format_s *fmt,
FAR struct fat_var_s *var)
{
int ret;
/* Select the number of root directory entries (FAT12/16 only). If FAT32 is selected,
* this value will be cleared later
*/
if (!fmt->ff_rootdirentries)
{
/* The caller did not specify the number of root directory entries; use a default of 512. */
fmt->ff_rootdirentries = 512;
}
/* Search to determine the smallest (reasonable) cluster size. A by-product
* of this search will be the selection of the FAT size (12/16/32) if the
* caller has not specified the FAT size
*/
ret = mkfatfs_clustersearch(fmt, var);
if (ret < 0)
{
fdbg("Failed to set cluster size\n");
return ret;
}
/* Perform FAT specific initialization */
/* Set up boot jump assuming FAT 12/16 offset to bootcode */
var->fv_jump[0] = OPCODE_JMP_REL8;
var->fv_jump[2] = OPCODE_NOP;
var->fv_bootcode = g_bootcodeblob;
var->fv_bootcodesize = sizeof(g_bootcodeblob);
if (var->fv_fattype != 32)
{
/* Set up additional, non-zero FAT12/16 fields */
/* Patch in the correct offset to the boot code */
var->fv_jump[1] = BS16_BOOTCODE - 2;
g_bootcodeblob[3] = BS16_BOOTCODE + BOOTCODE_MSGOFFSET;
}
else
{
/* Patch in the correct offset to the boot code */
var->fv_jump[1] = BS32_BOOTCODE - 2;
g_bootcodeblob[3] = BS32_BOOTCODE + BOOTCODE_MSGOFFSET;
/* The root directory is a cluster chain... its is initialize size is one cluster */
var->fv_nrootdirsects = 1 << fmt->ff_clustshift;
/* The number of reported root directory entries should should be zero for
* FAT32 because the root directory is a cluster chain.
*/
fmt->ff_rootdirentries = 0;
/* Verify the caller's backupboot selection */
if (fmt->ff_backupboot <= 1 || fmt->ff_backupboot >= fmt->ff_rsvdseccount)
{
fdbg("Invalid backup boot sector: %d\n", fmt->ff_backupboot);
fmt->ff_backupboot = 0;
}
/* Check if the caller has selected a location for the backup boot record */
if (!fmt->ff_backupboot)
{
/* There must be reserved sectors in order to have a backup boot sector */
if (fmt->ff_rsvdseccount > 0 && fmt->ff_rsvdseccount >= 2)
{
/* Sector 0 is the MBR; 1... ff_rsvdseccount are reserved. Try the next
* the last reserved sector.
*/
fmt->ff_backupboot = fmt->ff_rsvdseccount - 1;
if (fmt->ff_backupboot > 6)
{
/* Limit the location to within the first 7 */
fmt->ff_backupboot = 6;
}
}
}
}
/* Report the selected fat type */
fmt->ff_fattype = var->fv_fattype;
/* Describe the configured filesystem */
#ifdef CONFIG_DEBUG
fdbg("Sector size: %d bytes\n", var->fv_sectorsize);
fdbg("Number of sectors: %d sectors\n", fmt->ff_nsectors);
fdbg("FAT size: %d bits\n", var->fv_fattype);
fdbg("Number FATs: %d\n", fmt->ff_nfats);
fdbg("Sectors per cluster: %d sectors\n", 1 << fmt->ff_clustshift);
fdbg("FS size: %d sectors\n", var->fv_nfatsects);
fdbg(" %d clusters\n", var->fv_nclusters);
if (var->fv_fattype != 32)
{
fdbg("Root directory slots: %d\n", fmt->ff_rootdirentries);
}
fdbg("Volume ID: %08x\n", fmt->ff_volumeid);
fdbg("Volume Label: \"%c%c%c%c%c%c%c%c%c%c%c\"\n",
fmt->ff_volumelabel[0], fmt->ff_volumelabel[1], fmt->ff_volumelabel[2],
fmt->ff_volumelabel[3], fmt->ff_volumelabel[4], fmt->ff_volumelabel[5],
fmt->ff_volumelabel[6], fmt->ff_volumelabel[7], fmt->ff_volumelabel[8],
fmt->ff_volumelabel[9], fmt->ff_volumelabel[10]);
#endif
return OK;
}
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