sergio masci wrote:

> XCSB doesn't go the whole hog but it does track this much better than C.

> 	byte_var = byte_var + byte_var		// see (1)
> (1) ... add operation performed as two bytes

This is intuitive, and not significantly different from C. The result is
the same.

> 	byte_var = byte_var + word_var		// see (2)
> (2) ... add operation performed as two bytes

This is surprising, and may lead to a wrong result (for signed variables).
IMO this should at least trigger a compiler warning. 

> 	word_var = byte_var + byte_var		// see (3)
> (3) ... add operation performed as two words

This is not different from C.

> 	byte_var = (byte_var + byte_var) >> k	// see (4)
> (4) ... add operation performed as two words
> 	shift operation performed on word result

Considering 1, this is surprising. In any case, it's safe and not different
from C.

> 	byte_var = (ubyte)(byte_var + byte_var) >> k	// see (5)
> (5) ... add operation performed as two bytes
> 	shift operation performed on byte result

This is intuitive and not significantly different from C. The result is the
same.

Overall, these examples don't seem to show a significant difference from C,
with the exception of (2), of which I'm not sure it really makes more sense
than the way C does it.


> Also comparing signed and unsigned works correctly
> 
> e.g.
> 	if unsigned_byte_var > signed_byte_var then
> 
> 		always true if unsigned_byte_var > 127
> 		always false if signed_byte_var < 0
> 		otherwise true or false as expected
> 	endif

This is the same in C. 

(And as always, when talking about C in a generic fashion, I think ANSI C89
is probably a good candidate.)

Gerhard

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