// Set FormatPrecision if zero. We want to do this before we
// truncate trailing zeros, as those are part of the precision.
if (!FormatPrecision) {
- // It's an interesting question whether to use the nominal
- // precision or the active precision here for denormals.
+ // We use enough digits so the number can be round-tripped back to an
+ // APFloat. The formula comes from "How to Print Floating-Point Numbers
+ // Accurately" by Steele and White.
+ // FIXME: Using a formula based purely on the precision is conservative;
+ // we can print fewer digits depending on the actual value being printed.
- // FormatPrecision = ceil(significandBits / lg_2(10))
- FormatPrecision = (semantics->precision * 59 + 195) / 196;
+ // FormatPrecision = 2 + floor(significandBits / lg_2(10))
+ FormatPrecision = 2 + semantics->precision * 59 / 196;
}
// Ignore trailing binary zeros.
// change the payload.
if (isSignaling()) {
result = opInvalidOp;
- // For consistency, propogate the sign of the sNaN to the qNaN.
+ // For consistency, propagate the sign of the sNaN to the qNaN.
makeNaN(false, isNegative(), 0);
}
break;
// Decrement the significand.
//
// We always do this since:
- // 1. If we are dealing with a non binade decrement, by definition we
+ // 1. If we are dealing with a non-binade decrement, by definition we
// just decrement the significand.
// 2. If we are dealing with a normal -> normal binade decrement, since
// we have an explicit integral bit the fact that all bits but the