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Re: Two suggestions for gcc C compiler to extend C language (by WD Smith)

> On Jul 26, 2016, at 2:07 PM, Warren D Smith <> wrote:
> To the guy who falsely claimed MIPS fails to provide an add with carry
> instruction,
> a google search in 1 minute finds this:
> I defy you to find any processor not providing add with carry,
> (And I'm not talking about semantic bullshit.  MIPS provides add with
> carry, even if they do not call it that, as this answer shows.)


What that example shows is the standard assembly language coding for doing multi-precision addition in machines that do NOT have an add-with-carry instruction (or, as in the case of MIPS, even the concept of carry).  The algorithm is simple: add low order parts, see if the result is unsigned less than one of the operands; if yes, add one to the sum of the high order parts.

Incidentally, note that this coding pattern only works for two's complement integers.

> ...
> But the thing is, I'm not willing to write that stuff for you unless
> you promise to actually add these things to GCC.  So, will anybody
> make that promise?

I very much doubt it.  You might as well stop trying.


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