runtime/vm/bit_vector.cc

// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

#include "vm/bit_vector.h"

#include "vm/os.h"

namespace dart {

void BitVector::Iterator::Advance() {
  ++bit_index_;
  // Skip zero words.
  if (current_word_ == 0) {
    do {
      ++word_index_;
      if (Done()) return;
      current_word_ = target_->data_[word_index_];
    } while (current_word_ == 0);
    bit_index_ = word_index_ * kBitsPerWord;
  }
  // Skip zero bytes.
  while ((current_word_ & 0xff) == 0) {
    current_word_ >>= 8;
    bit_index_ += 8;
  }
  // Skip zero bits.
  while ((current_word_ & 0x1) == 0) {
    current_word_ >>= 1;
    ++bit_index_;
  }
  current_word_ = current_word_ >> 1;
}


bool BitVector::Equals(const BitVector& other) const {
  if (length_ != other.length_) return false;
  intptr_t i = 0;
  for (; i < data_length_ - 1; i++) {
    if (data_[i] != other.data_[i]) return false;
  }
  if (i < data_length_) {
    // Don't compare bits beyond length_.
    const intptr_t shift_size = (kBitsPerWord - length_) & (kBitsPerWord - 1);
    const uword mask = static_cast<uword>(-1) >> shift_size;
    if ((data_[i] & mask) != (other.data_[i] & mask)) return false;
  }
  return true;
}


bool BitVector::AddAll(const BitVector* from) {
  ASSERT(data_length_ == from->data_length_);
  bool changed = false;
  for (intptr_t i = 0; i < data_length_; i++) {
    const uword before = data_[i];
    const uword after = data_[i] | from->data_[i];
    if (before != after) {
      changed = true;
      data_[i] = after;
    }
  }
  return changed;
}


bool BitVector::RemoveAll(const BitVector* from) {
  ASSERT(data_length_ == from->data_length_);
  bool changed = false;
  for (intptr_t i = 0; i < data_length_; i++) {
    const uword before = data_[i];
    const uword after = data_[i] & ~from->data_[i];
    if (before != after) {
      changed = true;
      data_[i] = after;
    }
  }
  return changed;
}

bool BitVector::KillAndAdd(BitVector* kill, BitVector* gen) {
  ASSERT(data_length_ == kill->data_length_);
  ASSERT(data_length_ == gen->data_length_);
  bool changed = false;
  for (intptr_t i = 0; i < data_length_; i++) {
    const uword before = data_[i];
    const uword after = data_[i] | (gen->data_[i] & ~kill->data_[i]);
    if (before != after) changed = true;
    data_[i] = after;
  }
  return changed;
}


void BitVector::Intersect(const BitVector* other) {
  ASSERT(other->length() == length());
  for (intptr_t i = 0; i < data_length_; i++) {
    data_[i] = data_[i] & other->data_[i];
  }
}


bool BitVector::IsEmpty() const {
  for (intptr_t i = 0; i < data_length_; i++) {
    if (data_[i] != 0) {
      return false;
    }
  }
  return true;
}


void BitVector::Print() const {
  OS::Print("[");
  for (intptr_t i = 0; i < length_; i++) {
    OS::Print(Contains(i) ? "1" : "0");
  }
  OS::Print("]");
}

}  // namespace dart