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Diffstat (limited to 'cpukit/libfs/src/rfs/rtems-rfs-block-pos.h')
| -rw-r--r-- | cpukit/libfs/src/rfs/rtems-rfs-block-pos.h | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/cpukit/libfs/src/rfs/rtems-rfs-block-pos.h b/cpukit/libfs/src/rfs/rtems-rfs-block-pos.h new file mode 100644 index 0000000000..b15f0ba113 --- /dev/null +++ b/cpukit/libfs/src/rfs/rtems-rfs-block-pos.h @@ -0,0 +1,239 @@ +/* + * COPYRIGHT (c) 2010 Chris Johns <chrisj@rtems.org> + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.rtems.com/license/LICENSE. + * + * $Id$ + */ +/** + * @file + * + * @ingroup rtems-rfs + * + * RTEMS File Systems Block Position and Size Management. + * + * These functions manage the position in a block map as well as a size of data + * held in a block map. The position is the block count plus the offset into + * the last block where a block position of 0 and an offset of 0 is the start + * of a map. The size has a block count plus an offset, but the offset into the + * last block gives the actual size of the data in the map. This means a size + * will always have a block count greater than 0 when the file is not empty. A + * size offset of 0 and a non-zero block count means the length if aligned to + * the end of the block. For this reason there are 2 similar types so we know + * which set of rules are in use and the reason for this file. + */ + +#if !defined (_RTEMS_RFS_BLOCK_POS_H_) +#define _RTEMS_RFS_BLOCK_POS_H_ + +#include <rtems/rfs/rtems-rfs-file-system.h> +#include <rtems/rfs/rtems-rfs-inode.h> + +/** + * The block number is the same type as the inode block number. This makes sure + * the sizes of the types match. + */ +typedef rtems_rfs_inode_block rtems_rfs_block_no; + +/** + * The offset into a block. + */ +typedef uint32_t rtems_rfs_block_off; + +/** + * A block position is a block number times the block size plus the offset. The + * block field can be used hold a block number for the position as a look up + * cache. + */ +typedef struct rtems_rfs_block_pos_s +{ + /** + * The block index in the map. Range is from 0 to the maps block count minus + * 1. + */ + rtems_rfs_block_no bno; + + /** + * The offset into the block. Must be less than the block size. + */ + rtems_rfs_block_off boff; + + /** + * The block number that the bpos + boff map to. The 0 value is invalid and + * means no block number has been set. + */ + rtems_rfs_block_no block; + +} rtems_rfs_block_pos; + +/** + * Copy a block position. + * + * @param _lhs The left hand side. + * @param _rhs The right hand side. + */ +#define rtems_rfs_block_copy_bpos(_lhs, _rhs) \ + do { (_lhs)->bno = (_rhs)->bno; \ + (_lhs)->boff = (_rhs)->boff; \ + (_lhs)->block = (_rhs)->block; } while (0) + +/** + * Zero a block position. + * + * @param bpos A pointer to the block position. + */ +static inline void +rtems_rfs_block_set_bpos_zero (rtems_rfs_block_pos* bpos) +{ + bpos->bno = 0; + bpos->boff = 0; + bpos->block = 0; +} + +/** + * Given a position compute the block number and block offset. + * + * @param fs The file system data. + * @param pos The position as an absolute offset from the start. + * @param bpos Pointer to the block position to fill in. + */ +void rtems_rfs_block_get_bpos (rtems_rfs_file_system* fs, + rtems_rfs_pos pos, + rtems_rfs_block_pos* bpos); + +/** + * Given a block position compute the absolute offset. + * + * @param fs The file system data. + * @param bpos Pointer to the block position to fill in. + * @return rtems_rfs_pos The absolute offset. + */ +rtems_rfs_pos rtems_rfs_block_get_pos (rtems_rfs_file_system* fs, + rtems_rfs_block_pos* bpos); + +/** + * Add the relative position to the block position. The relative position is + * signed. + * + * @param fs The file system data. + * @param offset The relative offset add to the block position. + * @param bpos Pointer to the block position to fill in. + */ +static inline void +rtems_rfs_block_add_pos (rtems_rfs_file_system* fs, + rtems_rfs_pos_rel offset, + rtems_rfs_block_pos* bpos) +{ + rtems_rfs_block_get_bpos (fs, + rtems_rfs_block_get_pos (fs, bpos) + offset, + bpos); + bpos->block = 0; +} + +/** + * A block size is the number of blocks less one plus the offset where the + * offset must be less than the block size. + */ +typedef struct rtems_rfs_block_size_s +{ + /** + * The count of blocks in a map. A 0 means no blocks and a zero length and + * the offset should also be 0. + */ + rtems_rfs_block_no count; + + /** + * The offset into the block. An offset of 0 means block size, ie the first + * byte of the next block which is not allocated. + */ + rtems_rfs_block_off offset; + +} rtems_rfs_block_size; + +/** + * Copy a block size. + * + * @param _lhs The left hand side. + * @param _rhs The right hand side. + */ +#define rtems_rfs_block_copy_size(_lhs, _rhs) \ + do { (_lhs)->count = (_rhs)->count; \ + (_lhs)->offset = (_rhs)->offset; } while (0) + +/** + * Last block ? + */ +#define rtems_rfs_block_pos_last_block(_p, _s) \ + ((((_p)->bno == 0) && ((_s)->count == 0)) || ((_p)->bno == ((_s)->count - 1))) + +/** + * Last block ? + */ +#define rtems_rfs_block_pos_past_end(_p, _s) \ + (((_p)->bno && ((_s)->count == 0)) || \ + ((_p)->bno >= (_s)->count) || \ + (((_p)->bno == ((_s)->count - 1)) && ((_p)->boff > (_s)->offset))) + +/** + * Is the block position past the end. + */ +#define rtems_rfs_block_pos_block_past_end(_p, _s) \ + (((_p)->bno && ((_s)->count == 0)) || ((_p)->bno >= (_s)->count)) + +/** + * Copy the size to the block position. Note the block position and the size + * have different block counts. + */ +#define rtems_rfs_block_size_get_bpos(_s, _b) \ + do { (_b)->bno = (_s)->count; \ + (_b)->boff = (_s)->offset; \ + (_b)->block = 0; \ + if ((_b)->boff) --(_b)->bno; } while (0) + +/** + * Do the sizes match ? + */ +#define rtems_rfs_block_size_equal(_lhs, _rhs) \ + (((_lhs)->count == (_rhs)->count) && ((_lhs)->offset == (_rhs)->offset)) + +/** + * Zero a block size. + * + * @param size A pointer to the block size. + */ +static inline void +rtems_rfs_block_set_size_zero (rtems_rfs_block_size* size) +{ + size->count = 0; + size->offset = 0; +} + +/** + * Set the size given a position. + * + * @param fs The file system data. + * @param pos The position as an absolute offset from the start. + * @param size Pointer to the block size to fill in. + */ +void rtems_rfs_block_get_block_size (rtems_rfs_file_system* fs, + rtems_rfs_pos pos, + rtems_rfs_block_size* size); + +/** + * Calculate the position given the number of blocks and the offset. If the + * block count is 0 the size is 0. If the block is greater than 0 and the + * offset is 0 the size is number of blocks multipled by the block size and if + * the offset is not 0 it is the offset into the last block. For example if + * blocks is 1 and offset is 0 the size is the block size. If the block count + * is 1 and size is 100 the size is 100. + * + * @param fs The file system data. + * @param size The size in blocks and offset. + * @return rtems_rfs_pos The size in bytes. + */ +rtems_rfs_pos rtems_rfs_block_get_size (rtems_rfs_file_system* fs, + rtems_rfs_block_size* size); + +#endif |