[U-Boot-Users] Spartan FPGA patch

[Wolfgang Denk <wd@denx.de>]

In message <473AE49A.40801@inaccessnetworks.com> you wrote:
>
> This is the main misunderstanding. When you said "int" I though you 
> meant dereferencing an "int *", in fact not only me but other people on 
> the list as well. So your proposal is to convert the "char val" to an 
> "int val". You don't solve the problem I mentioned by doing this.

Well, the original error description said the problem was  caused  by
the  fact  that  "char"  might  be treated as "unsigned char" on some
platforms to the test for "< 0" would always fail.

> Let us not forget that all we want to do here is take the *bits* of the 
> buffer one by one, starting from the MSB. Checking for negativity is 
> just a hack to acquire the MSB, since signed values are two's complement.

If this was the intention of the code,  then  the  implementation  of
that  part  is  wrong (as has been pointed out before). Ii is already
wrong to assume that you are on a two complements machine...

> architectures, but I fail to see how this is cleaner than converting the 
> val to "unsigned char" like the "data" and doing "val & 0x80".

It depends on the purpose of the code (which I didn't bother  to  dig
into). If you want to really make a difference between <0 and >=0 you
should use integer types. If you want to test if a certain bit is set
or  not than you should use a logical AND operation. In this case the
bug was in using a '<0', not in the variable type.

I think we can close this now. A patch was submitted which cleans this
up.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
"Nobody will ever need more than 640k RAM!"       -- Bill Gates, 1981
"Windows 95 needs@least 8 MB RAM."             -- Bill Gates, 1996
"Nobody will ever need Windows 95."             -- logical conclusion