part/dev_desc: Add log2 of blocksize to block_dev_desc data struct
log2 of the device block size serves as the shift value used to calculate
the block number to read in file systems when implementing avaiable block
sizes.
It is needed quite often in file systems thus it is pre-calculated and
stored in the block device descriptor.
Signed-off-by: Egbert Eich <eich@suse.com>
diff --git a/include/part.h b/include/part.h
index 12e9b05..f7c7cc5 100644
--- a/include/part.h
+++ b/include/part.h
@@ -38,6 +38,7 @@
#endif
lbaint_t lba; /* number of blocks */
unsigned long blksz; /* block size */
+ int log2blksz; /* for convenience: log2(blksz) */
char vendor [40+1]; /* IDE model, SCSI Vendor */
char product[20+1]; /* IDE Serial no, SCSI product */
char revision[8+1]; /* firmware revision */
@@ -58,6 +59,10 @@
#define BLOCK_CNT(size, block_dev_desc) (PAD_COUNT(size, block_dev_desc->blksz))
#define PAD_TO_BLOCKSIZE(size, block_dev_desc) \
(PAD_SIZE(size, block_dev_desc->blksz))
+#define LOG2(x) (((x & 0xaaaaaaaa) ? 1 : 0) + ((x & 0xcccccccc) ? 2 : 0) + \
+ ((x & 0xf0f0f0f0) ? 4 : 0) + ((x & 0xff00ff00) ? 8 : 0) + \
+ ((x & 0xffff0000) ? 16 : 0))
+#define LOG2_INVALID(type) ((type)((sizeof(type)<<3)-1))
/* Interface types: */
#define IF_TYPE_UNKNOWN 0