From 451cbaa1c328082832a8fbcc427cd4416c602c5a Mon Sep 17 00:00:00 2001 From: OGAWA Hirofumi Date: Sun, 30 Oct 2005 15:03:49 -0800 Subject: [PATCH] fat: cleanup and optimization of checksum Signed-off-by: OGAWA Hirofumi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/msdos_fs.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'include/linux/msdos_fs.h') 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 @@ static inline u8 fat_attr(struct inode *inode) 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 -- cgit v1.1