Revision: 5789
Author: [email protected]
Date: Mon Nov 8 07:40:28 2010
Log: Add comments to double.h.
Review URL: http://codereview.chromium.org/4687001
http://code.google.com/p/v8/source/detail?r=5789
Modified:
/branches/bleeding_edge/src/double.h
=======================================
--- /branches/bleeding_edge/src/double.h Mon Nov 8 04:13:05 2010
+++ /branches/bleeding_edge/src/double.h Mon Nov 8 07:40:28 2010
@@ -54,18 +54,20 @@
explicit Double(DiyFp diy_fp)
: d64_(DiyFpToUint64(diy_fp)) {}
+ // The value encoded by this Double must be greater or equal to +0.0.
+ // It must not be special (infinity, or NaN).
DiyFp AsDiyFp() const {
+ ASSERT(Sign() > 0);
ASSERT(!IsSpecial());
return DiyFp(Significand(), Exponent());
}
- // this->Significand() must not be 0.
+ // The value encoded by this Double must be strictly greater than 0.
DiyFp AsNormalizedDiyFp() const {
+ ASSERT(value() > 0.0);
uint64_t f = Significand();
int e = Exponent();
- ASSERT(f != 0);
-
// The current double could be a denormal.
while ((f & kHiddenBit) == 0) {
f <<= 1;
@@ -82,6 +84,7 @@
return d64_;
}
+ // Returns the next greater double. Returns +infinity on input +infinity.
double NextDouble() const {
if (d64_ == kInfinity) return Double(kInfinity).value();
if (Sign() < 0 && Significand() == 0) {
@@ -144,14 +147,19 @@
return (d64 & kSignMask) == 0? 1: -1;
}
+ // Precondition: the value encoded by this Double must be greater or
equal
+ // than +0.0.
DiyFp UpperBoundary() const {
+ ASSERT(Sign() > 0);
return DiyFp(Significand() * 2 + 1, Exponent() - 1);
}
// Returns the two boundaries of this.
// The bigger boundary (m_plus) is normalized. The lower boundary has
the same
// exponent as m_plus.
+ // Precondition: the value encoded by this Double must be greater than 0.
void NormalizedBoundaries(DiyFp* out_m_minus, DiyFp* out_m_plus) const {
+ ASSERT(value() > 0.0);
DiyFp v = this->AsDiyFp();
bool significand_is_zero = (v.f() == kHiddenBit);
DiyFp m_plus = DiyFp::Normalize(DiyFp((v.f() << 1) + 1, v.e() - 1));
--
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