Re: casting from int to byte problem

Lew <>
Tue, 11 Sep 2007 11:37:22 -0400
Twisted wrote:

Lew wrote:
[snip attack post]


Stop attacking me.

If you'd bothered to read my post you would see that I said nothing about you
at all, much less attacked you.

He was not referring to widening versus narrowing; he was referring to
widening with sign extension vs. widening without sign extension.

Your whole vicious attack post is predicated on a wrong assumption,
which is easy to check if you'd bother to read the original post.

Here's an excerpt from the original post about "inverse":

When you did a byte move
into a register (registers were all 16 bits) it was sign extended by


If you did a byte move to the register, and performed math on it
(16 bit), and did a byte move back to memory, or to an IO device, what
happened in the high order 8 bits wasn't important.


So, given the fact that when doing 8 bit operations, it made no
difference which way it worked, and when doing 8 bit to 16 bit conversion,
one default required 2 extra instructions to do the inverse, and the other
default only required 1 extra instruction, they picked the default that
made the inverse easier.

 From that last sentence, it is clear that the two options of "sign extend" or
"no sign extend" are choices to be applied to the same "inverse" operation,
therefore he was not talking about "not sign extend" as the inverse of "sign
extend". Also, it is clear that nothing in his comment was an obverse of
anything else. From the context, I concluded that "when doing 8-bit
operations" referred to the narrowing of 16 to 8 bits, so clearly "when doing
8 bit [sic] to 16 bit [sic] conversion" is intended to be the "inverse"
operation under discussion.

So, despite your vicious inflammatory attack ("if you'd bother"), it is clear
that I did, indeed, read the original post, and that I drew my conclusions
from it. Conclusions, not assumptions, in that they are the product of
reasoning supported by evidence, /a posteriori/.

Anyhow, even if I'm wrong, which I might be, about what Curt meant by
"inverse", there is no way that "obverse" applies.

I notice that in your /ad hominem/ post you completely neglected to address
that point, the central point that I made. Hmm.

So if you have a better choice than "inverse" that is not so clearly
inappropriate and inapplicable as "obverse", let's hear it. I'm satisfied
that I understood the sense of the post, whether "inverse" is exactly right or
not, and I'm simply seeking to illuminate the process by which I arrived at my
understanding. I respect your right to disagree and see it differently.


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