diff options
Diffstat (limited to 'nuttx/fs/fat/fs_fat32.h')
| -rw-r--r-- | nuttx/fs/fat/fs_fat32.h | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/nuttx/fs/fat/fs_fat32.h b/nuttx/fs/fat/fs_fat32.h index 3dfc0aae2..9e76f9ff9 100644 --- a/nuttx/fs/fat/fs_fat32.h +++ b/nuttx/fs/fat/fs_fat32.h @@ -195,6 +195,31 @@ #define FAT_BAD 0x0ffffff7 /**************************************************************************** + * Maximum cluster by FAT type. This is the key value used to distinquish + * between FAT12, 16, and 32. + */ + +/* FAT12: For M$, the calculation is ((1 << 12) - 19). But we will follow the + * Linux tradition of allowing slightly more clusters for FAT12. + */ + +#define FAT_MAXCLUST12 ((1 << 12) - 16) + +/* FAT16: For M$, the calculation is ((1 << 16) - 19). */ + +#define FAT_MINCLUST16 (FAT_MAXCLUST12 + 1) +#define FAT_MAXCLUST16 ((1 << 16) - 16) + +/* FAT32: M$ reserves the MS 4 bits of a FAT32 FAT entry so only 18 bits are + * available. For M$, the calculation is ((1 << 28) - 19). + */ + +#define FAT_MINCLUST32 65524 +/* #define FAT_MINCLUST32 (FAT_MAXCLUST16 + 1) */ +#define FAT_MAXCLUST32 ((1 << 28) - 16) + + +/**************************************************************************** * Access to data in raw sector data */ #define UBYTE_VAL(p,o) (((ubyte*)(p))[o]) |