Re: sizeof(long long)

[Erik Trulsson <ertr1013 at student dot uu dot se>]

On Tue, Nov 19, 2002 at 03:28:28PM +0100, Svein E. Seldal wrote:
> Hi,
> 
> Is it a strict requirement of C that "long long" is 64-bits? Or is it 
> simply that sizeof(long long)>sizeof(long) (or maybe >=)?

"long long" must be *at least* 64 bits.  (And should be at least as wide as
long.)


> 
> In the AVR target, this the sizeof's are distributed as such: 
> sizeof(char)=1, sizeof(short)=sizeof(int)=2, sizeof(long)=4, sizeof(long 
> long)=8.

That is fine.  (Assuming 8-bit bytes.)


> 
> Since this is a small microcontroller, it has the -mint8 option, which 
> does the following: sizeof(char)=sizeof(short)=sizeof(int)=1, 
> sizeof(long)=2 and sizeof(long long)=8.

This is not acceptable to the C standard, which requires that
short and int must be at least 16 bits each and that long must have at
least 32 bits.  

(Actually the C standard talks about what values must be representable by
the various types, but it translates to the above bitsizes.)

> 
> Note that there is a gap between long and long long. No 32-bits types 
> exists for this mode -- this represents surely a problem when 32-bits 
> types are wanted. My idead would then to decrease the long long size to 
> be 32-bit.
> 
> I have a patch for it, but I wanted to make sure that this construct is 
> valid..

32-bit long long is not valid acording to the C standard, but since I
suspect there are many things in that mode that do not conform to the C
standard I expect one more thing would not cause any major problems.



-- 
<Insert your favourite quote here.>
Erik Trulsson
ertr1013@student.uu.se