On Fri, Jun 1, 2018 at 11:13 AM, J. Gareth Moreton < gar...@moreton-family.com> wrote:
> Hi everyone, > > I'm starting to make some modifications to the optimizer so it optimises > div and mod operations on signed integers (I've done unsigned integers > already). One question that I've stumbled across... what are the rules > regarding the sign of the result? Experimenting with IDIV suggests it > returns a negative modulus only if the numerator is positive (so -28 / 3 = > -9 remainder -1, and -28 / -3 = 9 remainder -1, but 28 / -3 = -9 remainder > +1), which follows the Euclidean division rule of n = dq + r, where n is > the numerator, d is the divisor, q is the resultant quotient and r is the > resultant remainder. > > While I'm planning on being consistent with IDIV, what are the rules of > signed division in Free Pascal? There are hints that some dialects of > Pascal only return a positive modulus no matter what. > > Gareth aka. Kit > " The sign of the result of a Mod operator is the same as the sign of the left side operand of the Mod operator " - https://freepascal.org/docs-html/current/ref/refsu45.html
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