[Debburn-devel] [PATCH] fixes for aliasing bugs

[Peter Samuelson]

[Albert Cahalan]
> >It occurred to me after sending this that I didn't actually know what
> >(unsigned)*inp would do.  As it turns out, it sign-extends to int
> >_before_ interpreting as unsigned int, the opposite of what I had
> >expected.

> Assuming you just want to eliminate a warning about a signed value
> as an array index, I think you want this:
> 
> a2h[*inp - 192u];

No, that gives the wrong result if *inp is a signed char with a value
of, say, -15 (that is, 0xf1) - this will yield an array index of -207.
If that is interpreted as an unsigned value, like a size_t, it becomes
4294967089.  Neither is what we want: what we want is 49.  You have to
cast *inp to unsigned char first, that's just all there is to it.
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