RE: [lwip-users] Problem With dns.c Using 32-Bit Compilers

[Bill Auerbach]

> I'm not sure which ARM processor you're referring to, but that can't
> actually be true. By definition in the C standard, every compiler is
> guaranteed to have byte access anywhere it wants (IIRC, a byte is
> defined as the minimal unit addressable on the architecture). The fun
> part is that a byte (as defined by the C standard) is not guaranteed to
> have 8-bits!

Are there really any processors in the last 10-20 years that didn't have
bytes that are 8-bits?

To be semantically correct, C defines char (not byte).  Sizeof char is
always 1, and if bytes have 8-bits, then the compiler is guaranteed to load
chars as you stated.  Then it follows that macros are possible that do 2
char accesses.  The macros I posted that do this work - they do 2 separate
byte reads and form the final int.  This should work everywhere.

Bill

> 
> Jared
> 
> -----Original Message-----
> From: address@hidden [mailto:lwip-
> address@hidden On Behalf Of Alain M.
> Sent: Friday, August 29, 2008 09:37
> To: Mailing list for lwIP users
> Subject: Re: [lwip-users] Problem With dns.c Using 32-Bit Compilers
> 
> Then we can make macros to be that and optimyzed. There could be a file
> of such macros for a few architectures. Let me try an example por ARM
> which is intereting because it is 32 bit and does not have byte access:
> 
> 
> 
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