Ian McDonnell,

I used unsigned char's in place of the unsigned int's in struct yaffs_ECCOther,
It works!
Thanks again for help!!!

Index: yaffs_ecc.h
===================================================================
--- yaffs_ecc.h £¨ÐÞ¶©°æ 100£©
+++ yaffs_ecc.h £¨¹¤×÷¿½±´£©
@@ -32,8 +32,8 @@

 typedef struct {
        unsigned char colParity;
-       unsigned lineParity;
-       unsigned lineParityPrime;
+       unsigned char lineParity;
+       unsigned char lineParityPrime;
 } yaffs_ECCOther;

 void yaffs_ECCCalculate(const unsigned char *data, unsigned char *ecc);


2007/7/5, ian@brightstareng.com <ian@brightstareng.com>:
> On Thursday 05 July 2007 00:32, He Yong wrote:
> > sorry, I made a mistake. the yaffs2's mini-ecc actually only
> > checks the 16 bytes of ext tags (struct
> > yaffs_PackedTags2TagsPart).
> Yes, I call the tags ecc the "mini-ECC", it is not the main ECC
> that covers the user's data.  It protects the integrity of the
> tags data.
>
> > and generates 9 bytes of parity
> > code (struct yaffs_ECCOther). but the sizeof(struct
> > yaffs_ECCOther) = 12 byte, simply because the struct is 4-byte
> > aligned, I made a little change to save 3 bytes for other
> > usage (like mtd bad block mark).
>
> Did you try using unsigned char's in place of the unsigned int's
> in struct yaffs_ECCOther, see
> http://balloonboard.org/lurker/message/20070702.161336.5e273493.en.html
>
> It should be easy to reduce struct yaffs_PackedTags2 to just 20
> bytes: 4 ints + 3 chars + 1 alignment byte -- so only 19 bytes
> of real data.  This should work without any introducing any
> functional differences.  The code in yaffs_packedtags2.c uses
> sizeof(struct) for the length so I do not think there is any need
> to change the i/o code if you can work with 20-byte tags.
>
> -imcd
>



-- 
Best Regards!

He Yong

School of Information Security,
Shanghai Jiaotong University,
Dong cuan Road #800,
Minhang, Shanghai, P.R.China