Re: [xmlvm-dev] byte sign

[Panayotis K. <pan...@pa...>]

On Apr 5, 2011, at 8:49 PM, Arno Puder wrote:

> 
> things are a little trickier. According to section 2.4.1 of the Java 
> Specs: "The integral types are byte, short, int, and long, whose values 
> are 8-bit, 16-bit, 32-bit, and 64-bit signed two's-complement integers, 
> respectively, and char, whose values are 16-bit unsigned integers 
> representing Unicode characters"
> 
> Then in Section 3.11.1 of the Java spec it says: "Note that most 
> instructions in Table 3.2 do not have forms for the integral types byte, 
> char, and short. None have forms for the boolean type. Compilers encode 
> loads of literal values of types byte and short using Java virtual 
> machine instructions that sign-extend those values to values of type int 
> at compile time or run time. Loads of literal values of types boolean 
> and char are encoded using instructions that zero-extend the literal to 
> a value of type int at compile time or run time."
> 
> So, you are correct that a byte is a signed 8-bit value, however it 
> needs to be properly sign extended. In the C backend I already use 
> typedef's consistently, so it should be easy to fix. The Objective-C 
> backend is not as cleanly implemented.
> 
> Arno
> 


So, the problem remains, should "byte" be a signed or unsigned char under ObjC backend, and especially in the Byte methods?
My understanding is that it is sometimes a signed integer, but in any case, it is *not* an unsigned char.