You are a stupid programmer, you can't have that

[H. S. Teoh]

On Mon, Aug 09, 2021 at 08:18:26PM +0000, Paul Backus via Digitalmars-d wrote:
> On Monday, 9 August 2021 at 19:23:14 UTC, H. S. Teoh wrote:
> > As Knuth once said:
> > 
> > 	People who are more than casually interested in computers should
> > 	have at least some idea of what the underlying hardware is like.
> > 	Otherwise the programs they write will be pretty weird.
> > 	-- D. Knuth
> > 
> > That includes knowing the ugly realities of 2's complement
> > arithmetic.
> 
> The way I remember it, 2's complement notation is a method of encoding
> signed integers as unsigned integers such that a CPU can use the same
> instructions and circuits for both signed and unsigned arithmetic.
> 
> So, from the hardware's point of view, unsigned arithmetic is the
> pure, simple version, and signed arithmetic is the ugly, complex
> version. :)

Indeed!  If you look at the assembly level, unsigned arithmetic is the
one with straightforward instructions mapping 1-to-1 with arithmetic
operations, whereas signed arithmetic is the one that involves carry
bits and other such additional complications.


T

-- 
Heads I win, tails you lose.