Commit 451cbaa1 authored by OGAWA Hirofumi's avatar OGAWA Hirofumi Committed by Linus Torvalds

[PATCH] fat: cleanup and optimization of checksum

Signed-off-by: default avatarOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 4e57b681
...@@ -263,7 +263,6 @@ int fat_search_long(struct inode *inode, const unsigned char *name, ...@@ -263,7 +263,6 @@ int fat_search_long(struct inode *inode, const unsigned char *name,
unsigned char id; unsigned char id;
unsigned char slot; unsigned char slot;
unsigned char slots; unsigned char slots;
unsigned char sum;
unsigned char alias_checksum; unsigned char alias_checksum;
if (!unicode) { if (!unicode) {
...@@ -317,9 +316,7 @@ int fat_search_long(struct inode *inode, const unsigned char *name, ...@@ -317,9 +316,7 @@ int fat_search_long(struct inode *inode, const unsigned char *name,
goto parse_long; goto parse_long;
if (IS_FREE(de->name) || (de->attr & ATTR_VOLUME)) if (IS_FREE(de->name) || (de->attr & ATTR_VOLUME))
continue; continue;
for (sum = 0, i = 0; i < 11; i++) if (fat_checksum(de->name) != alias_checksum)
sum = (((sum&1)<<7)|((sum&0xfe)>>1)) + de->name[i];
if (sum != alias_checksum)
nr_slots = 0; nr_slots = 0;
} }
...@@ -479,7 +476,6 @@ static int fat_readdirx(struct inode *inode, struct file *filp, void *dirent, ...@@ -479,7 +476,6 @@ static int fat_readdirx(struct inode *inode, struct file *filp, void *dirent,
unsigned char id; unsigned char id;
unsigned char slot; unsigned char slot;
unsigned char slots; unsigned char slots;
unsigned char sum;
unsigned char alias_checksum; unsigned char alias_checksum;
if (!unicode) { if (!unicode) {
...@@ -534,9 +530,7 @@ static int fat_readdirx(struct inode *inode, struct file *filp, void *dirent, ...@@ -534,9 +530,7 @@ static int fat_readdirx(struct inode *inode, struct file *filp, void *dirent,
goto ParseLong; goto ParseLong;
if (IS_FREE(de->name) || (de->attr & ATTR_VOLUME)) if (IS_FREE(de->name) || (de->attr & ATTR_VOLUME))
goto RecEnd; goto RecEnd;
for (sum = 0, i = 0; i < 11; i++) if (fat_checksum(de->name) != alias_checksum)
sum = (((sum&1)<<7)|((sum&0xfe)>>1)) + de->name[i];
if (sum != alias_checksum)
long_slots = 0; long_slots = 0;
} }
......
...@@ -621,8 +621,7 @@ static int vfat_build_slots(struct inode *dir, const unsigned char *name, ...@@ -621,8 +621,7 @@ static int vfat_build_slots(struct inode *dir, const unsigned char *name,
} }
/* build the entry of long file name */ /* build the entry of long file name */
for (cksum = i = 0; i < 11; i++) cksum = fat_checksum(msdos_name);
cksum = (((cksum&1)<<7)|((cksum&0xfe)>>1)) + msdos_name[i];
*nr_slots = usize / 13; *nr_slots = usize / 13;
for (ps = slots, i = *nr_slots; i > 0; i--, ps++) { for (ps = slots, i = *nr_slots; i > 0; i--, ps++) {
......
...@@ -282,6 +282,17 @@ static inline u8 fat_attr(struct inode *inode) ...@@ -282,6 +282,17 @@ static inline u8 fat_attr(struct inode *inode)
MSDOS_I(inode)->i_attrs; 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) 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 return ((sector_t)clus - FAT_START_ENT) * sbi->sec_per_clus
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment