Changes in uspace/srv/fs/fat/fat_fat.h [991f645:d260a95] in mainline

File:

• uspace/srv/fs/fat/fat_fat.h (modified) (3 diffs)

uspace/srv/fs/fat/fat_fat.h

@@ -29 +29 @@
 /** @addtogroup fs
  * @{
- */ 
+ */
 
 #ifndef FAT_FAT_FAT_H_
@@ -40 +40 @@
 #define FAT1            0
 
-#define FAT_CLST_RES0   0x0000
-#define FAT_CLST_RES1   0x0001
-#define FAT_CLST_FIRST  0x0002
-#define FAT_CLST_BAD    0xfff7
-#define FAT_CLST_LAST1  0xfff8
-#define FAT_CLST_LAST8  0xffff
+#define FAT_CLST_RES0     0x0000
+#define FAT_CLST_RES1     0x0001
+#define FAT_CLST_FIRST    0x0002
+
+#define FAT12_CLST_BAD    0x0ff7
+#define FAT12_CLST_LAST1  0x0ff8
+#define FAT12_CLST_LAST8  0x0fff
+#define FAT16_CLST_BAD    0xfff7
+#define FAT16_CLST_LAST1  0xfff8
+#define FAT16_CLST_LAST8  0xffff
+
+#define FAT12_CLST_MAX    4085
+#define FAT16_CLST_MAX    65525
 
 /* internally used to mark root directory's parent */
@@ -51 +58 @@
 /* internally used to mark root directory */
 #define FAT_CLST_ROOT           FAT_CLST_RES1
+
+/*
+ * Convenience macros for computing some frequently used values from the
+ * primitive boot sector members.
+ */
+#define RDS(bs)   ((sizeof(fat_dentry_t) * RDE((bs))) / BPS((bs))) + \
+                   (((sizeof(fat_dentry_t) * RDE((bs))) % BPS((bs))) != 0)
+#define SSA(bs)   (RSCNT((bs)) + FATCNT((bs)) * SF((bs)) + RDS(bs))
+#define DS(bs)    (TS(bs) - SSA(bs))
+#define CC(bs)    (DS(bs) / SPC(bs))
+
+#define FAT_IS_FAT12(bs)        (CC(bs) < FAT12_CLST_MAX)
+#define FAT_IS_FAT16(bs) \
+    ((CC(bs) >= FAT12_CLST_MAX) && (CC(bs) < FAT16_CLST_MAX))
+
+#define FAT_CLST_LAST1(bs) \
+    (FAT_IS_FAT12(bs) ? FAT12_CLST_LAST1 : FAT16_CLST_LAST1)
+#define FAT_CLST_LAST8(bs) \
+    (FAT_IS_FAT12(bs) ? FAT12_CLST_LAST8 : FAT16_CLST_LAST8)
+#define FAT_CLST_BAD(bs) \
+    (FAT_IS_FAT12(bs) ? FAT12_CLST_BAD : FAT16_CLST_BAD)
 
 /* forward declarations */