[PATCH] fat: cleanup and optimization of checksum
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/msdos_fs.h b/include/linux/msdos_fs.h
index 9a3d272..941da5c 100644
--- a/include/linux/msdos_fs.h
+++ b/include/linux/msdos_fs.h
@@ -282,6 +282,17 @@
MSDOS_I(inode)->i_attrs;
}
+static inline unsigned char fat_checksum(const __u8 *name)
+{
+ unsigned char s = name[0];
+ s = (s<<7) + (s>>1) + name[1]; s = (s<<7) + (s>>1) + name[2];
+ s = (s<<7) + (s>>1) + name[3]; s = (s<<7) + (s>>1) + name[4];
+ s = (s<<7) + (s>>1) + name[5]; s = (s<<7) + (s>>1) + name[6];
+ s = (s<<7) + (s>>1) + name[7]; s = (s<<7) + (s>>1) + name[8];
+ s = (s<<7) + (s>>1) + name[9]; s = (s<<7) + (s>>1) + name[10];
+ return s;
+}
+
static inline sector_t fat_clus_to_blknr(struct msdos_sb_info *sbi, int clus)
{
return ((sector_t)clus - FAT_START_ENT) * sbi->sec_per_clus