+ /// reset - Efficiently reset a range of bits in [I, E)
+ BitVector &reset(unsigned I, unsigned E) {
+ assert(I <= E && "Attempted to reset backwards range!");
+ assert(E <= size() && "Attempted to reset out-of-bounds range!");
+
+ if (I == E) return *this;
+
+ if (I / BITWORD_SIZE == E / BITWORD_SIZE) {
+ BitWord EMask = 1UL << (E % BITWORD_SIZE);
+ BitWord IMask = 1UL << (I % BITWORD_SIZE);
+ BitWord Mask = EMask - IMask;
+ Bits[I / BITWORD_SIZE] &= ~Mask;
+ return *this;
+ }
+
+ BitWord PrefixMask = ~0UL << (I % BITWORD_SIZE);
+ Bits[I / BITWORD_SIZE] &= ~PrefixMask;
+ I = RoundUpToAlignment(I, BITWORD_SIZE);
+
+ for (; I + BITWORD_SIZE <= E; I += BITWORD_SIZE)
+ Bits[I / BITWORD_SIZE] = 0UL;
+
+ BitWord PostfixMask = (1UL << (E % BITWORD_SIZE)) - 1;
+ Bits[I / BITWORD_SIZE] &= ~PostfixMask;
+
+ return *this;
+ }
+