}
operator bool() const {
- return (*WordRef) & (1L << BitPos);
+ return ((*WordRef) & (1L << BitPos)) ? true : false;
}
};
init_words(&Bits[OldCapacity], (Capacity-OldCapacity), t);
}
- // If we previously had no size, initialize the low word
- if (Size == 0)
- Bits[0] = t;
+ // Set any old unused bits that are now included in the BitVector. This
+ // may set bits that are not included in the new vector, but we will clear
+ // them back out below.
+ if (N > Size)
+ set_unused_bits(t);
+ // Update the size, and clear out any bits that are now unused
+ unsigned OldSize = Size;
Size = N;
- clear_unused_bits();
+ if (t || N < OldSize)
+ clear_unused_bits();
}
void reserve(unsigned N) {
// Comparison operators.
bool operator==(const BitVector &RHS) const {
- if (Size != RHS.Size)
- return false;
-
- for (unsigned i = 0; i < NumBitWords(size()); ++i)
+ unsigned ThisWords = NumBitWords(size());
+ unsigned RHSWords = NumBitWords(RHS.size());
+ unsigned i;
+ for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
if (Bits[i] != RHS.Bits[i])
return false;
+
+ // Verify that any extra words are all zeros.
+ if (i != ThisWords) {
+ for (; i != ThisWords; ++i)
+ if (Bits[i])
+ return false;
+ } else if (i != RHSWords) {
+ for (; i != RHSWords; ++i)
+ if (RHS.Bits[i])
+ return false;
+ }
return true;
}
// Intersection, union, disjoint union.
BitVector operator&=(const BitVector &RHS) {
- assert(Size == RHS.Size && "Illegal operation!");
- for (unsigned i = 0; i < NumBitWords(size()); ++i)
+ unsigned ThisWords = NumBitWords(size());
+ unsigned RHSWords = NumBitWords(RHS.size());
+ unsigned i;
+ for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
Bits[i] &= RHS.Bits[i];
+
+ // Any bits that are just in this bitvector become zero, because they aren't
+ // in the RHS bit vector. Any words only in RHS are ignored because they
+ // are already zero in the LHS.
+ for (; i != ThisWords; ++i)
+ Bits[i] = 0;
+
return *this;
}
}
// Grow the bitvector to have enough elements.
- Capacity = NumBitWords(Size);
+ Capacity = RHSWords;
BitWord *NewBits = new BitWord[Capacity];
std::copy(RHS.Bits, &RHS.Bits[RHSWords], NewBits);
unsigned NumBitWords(unsigned S) const {
return (S + BITWORD_SIZE-1) / BITWORD_SIZE;
}
-
- // Clear the unused top bits in the high word.
- void clear_unused_bits() {
+
+ // Set the unused bits in the high words.
+ void set_unused_bits(bool t = true) {
+ // Set high words first.
+ unsigned UsedWords = NumBitWords(Size);
+ if (Capacity > UsedWords)
+ init_words(&Bits[UsedWords], (Capacity-UsedWords), t);
+
+ // Then set any stray high bits of the last used word.
unsigned ExtraBits = Size % BITWORD_SIZE;
if (ExtraBits) {
- unsigned index = Size / BITWORD_SIZE;
- Bits[index] &= ~(~0L << ExtraBits);
+ Bits[UsedWords-1] &= ~(~0L << ExtraBits);
+ Bits[UsedWords-1] |= (0 - (BitWord)t) << ExtraBits;
}
}
+ // Clear the unused bits in the high words.
+ void clear_unused_bits() {
+ set_unused_bits(false);
+ }
+
void grow(unsigned NewSize) {
unsigned OldCapacity = Capacity;
Capacity = NumBitWords(NewSize);