| 110,16 → 110,84 |
|---|
| return NULL; /* TODO */ |
| } |
| |
| static block_t *fat_block_get(dev_handle_t dev_handle, fs_index_t index, |
| off_t offset) { |
| return NULL; /* TODO */ |
| } |
| |
| static void block_put(block_t *block) |
| { |
| /* TODO */ |
| } |
| |
| |
| #define FAT_BS(b) ((fat_bs_t *)((b)->data)) |
| |
| #define FAT_CLST_FIRST 0x0002 |
| #define FAT_CLST_BAD 0xfff7 |
| #define FAT_CLST_LAST1 0xfff8 |
| #define FAT_CLST_LAST8 0xffff |
| |
| /** Convert cluster number to an index within a FAT. |
| * |
| * Format Identifier and cluster numbering is considered. |
| */ |
| #define C2FAT_IDX(c) (1 + (c) - FAT_CLST_FIRST) |
| |
| static block_t *fat_block_get(dev_handle_t dev_handle, fs_index_t index, |
| off_t offset) |
| { |
| block_t *bb; |
| block_t *b; |
| unsigned bps; |
| unsigned spc; |
| unsigned rscnt; /* block address of the first FAT */ |
| unsigned fatcnt; |
| unsigned rde; |
| unsigned rds; /* root directory size */ |
| unsigned sf; |
| unsigned ssa; /* size of the system area */ |
| unsigned clusters; |
| unsigned clst = index; |
| unsigned i; |
| |
| bb = block_get(dev_handle, BS_BLOCK); |
| bps = uint16_t_le2host(FAT_BS(bb)->bps); |
| spc = FAT_BS(bb)->spc; |
| rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt); |
| fatcnt = FAT_BS(bb)->fatcnt; |
| rde = uint16_t_le2host(FAT_BS(bb)->root_ent_max); |
| sf = uint16_t_le2host(FAT_BS(bb)->sec_per_fat); |
| block_put(bb); |
| |
| rds = (sizeof(fat_dentry_t) * rde) / bps; |
| rds += ((sizeof(fat_dentry_t) * rde) % bps != 0); |
| ssa = rscnt + fatcnt * sf + rds; |
| |
| if (!index) { |
| /* root directory special case */ |
| assert(offset < rds); |
| b = block_get(dev_handle, rscnt + fatcnt * sf + offset); |
| return b; |
| } |
| |
| clusters = offset / spc; |
| for (i = 0; i < clusters; i++) { |
| unsigned fsec; /* sector offset relative to FAT1 */ |
| unsigned fidx; /* FAT1 entry index */ |
| |
| assert(clst >= FAT_CLST_FIRST && clst < FAT_CLST_BAD); |
| fsec = (C2FAT_IDX(clst) * sizeof(uint16_t)) / bps; |
| fidx = C2FAT_IDX(clst) % (bps / sizeof(uint16_t)); |
| /* read FAT1 */ |
| b = block_get(dev_handle, rscnt + fsec); |
| clst = uint16_t_le2host(((uint16_t *)b->data)[fidx]); |
| assert(clst != FAT_CLST_BAD); |
| assert(clst < FAT_CLST_LAST1); |
| block_put(b); |
| } |
| |
| b = block_get(dev_handle, ssa + (clst - FAT_CLST_FIRST) * spc + |
| offset % spc); |
| |
| return b; |
| } |
| |
| static void fat_node_initialize(fat_node_t *node) |
| { |
| futex_initialize(&node->lock, 1); |
| 142,7 → 210,7 |
|---|
| |
| bb = block_get(dev_handle, BS_BLOCK); |
| assert(bb != NULL); |
| bps = uint16_t_le2host(((fat_bs_t *)bb->data)->bps); |
| bps = uint16_t_le2host(FAT_BS(bb)->bps); |
| block_put(bb); |
| |
| return bps; |