On Sat, 11 Aug 2012 09:48:15 -0400, David <d...@dav1d.de> wrote:
-1 % 16 = -1
Shouldn't that be 15? It seems like the sign is ignored for the modulo.
Is this a bug or intended behaviour? The Python implementation returns
here, as expected, 15.
In case you are still looking for an expression which mods always positive
(even for non-powers of 2)
(a % b + b) % b
Obviously, b must be positive.
The direct translation of this to assembly isn't the most efficient way.
Technically, in assembly we could check for the sign bit, and only add b
again (without doing the second mod) if the value was negative. But I'm
not sure you can write an expression that causes that, maybe:
a % b < 0 ? a % b + b : a % b
Certainly not as appealing. To get a direct translation from the above
assembly, it would be something like:
typeof(a) x;
auto expr = (x = a % b) < 0 ? x + b : x
-Steve
