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numeric.c: round_to_nearest

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* numeric.c (round_to_nearest): extract and reduce for platforms
  where round is not available.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55897 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
nobu 2016-08-15 01:59:58 +00:00
parent dfe1d4fda6
commit ab65e9d983
1 changed files with 26 additions and 7 deletions
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33
numeric.c
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@ -92,6 +92,31 @@ round(double x)
}
#endif
static double
round_to_nearest(double x, double s)
{
double f, xs = x * s;
#ifdef HAVE_ROUND
f = round(xs);
#endif
if (x > 0) {
#ifndef HAVE_ROUND
f = floor(xs);
#endif
if ((double)((f + 0.5) / s) <= x) f += 1;
x = f;
}
else {
#ifndef HAVE_ROUND
f = ceil(xs);
#endif
if ((double)((f - 0.5) / s) >= x) f -= 1;
x = f;
}
return x;
}
static VALUE fix_uminus(VALUE num);
static VALUE fix_mul(VALUE x, VALUE y);
static VALUE fix_lshift(long, unsigned long);
@ -2089,13 +2114,7 @@ flo_round(int argc, VALUE *argv, VALUE num)
}
if (float_invariant_round(number, ndigits, &num)) return num;
f = pow(10, ndigits);
x = round(number * f);
if (x > 0) {
if ((double)((x + 0.5) / f) <= number) x += 1;
}
else {
if ((double)((x - 0.5) / f) >= number) x -= 1;
}
x = round_to_nearest(number, f);
return DBL2NUM(x / f);
}