blob: 74c4c5b5c44279125990200a229a1307709baa08 [file] [log] [blame]
// 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/allocation.h"
#include "vm/datastream.h"
#include "vm/thread_state.h"
#include "vm/zone.h"
namespace dart {
// BitmapBuilder is used to build a bitmap. The implementation is optimized
// for a dense set of small bit maps without a fixed upper bound (e.g: a
// pointer map description of a stack).
class BitmapBuilder : public ZoneAllocated {
BitmapBuilder() : length_(0), data_size_in_bytes_(kInlineCapacityInBytes) {
memset(data_.inline_, 0, data_size_in_bytes_);
BitmapBuilder(const BitmapBuilder& other)
: ZoneAllocated(),
data_size_in_bytes_(other.data_size_in_bytes_) {
if (data_size_in_bytes_ == kInlineCapacityInBytes) {
memmove(data_.inline_, other.data_.inline_, kInlineCapacityInBytes);
} else {
data_.ptr_ = AllocBackingStore(data_size_in_bytes_);
memmove(data_.ptr_, other.data_.ptr_, data_size_in_bytes_);
intptr_t Length() const { return length_; }
void SetLength(intptr_t length);
// Get/Set individual bits in the bitmap, setting bits beyond the bitmap's
// length increases the length and expands the underlying bitmap if
// needed.
bool Get(intptr_t bit_offset) const;
void Set(intptr_t bit_offset, bool value);
// Return the bit offset of the highest bit set.
intptr_t Maximum() const;
// Return the bit offset of the lowest bit set.
intptr_t Minimum() const;
// Sets min..max (inclusive) to value.
void SetRange(intptr_t min, intptr_t max, bool value);
void Print() const;
void AppendAsBytesTo(BaseWriteStream* stream) const;
static constexpr intptr_t kIncrementSizeInBytes = 16;
static constexpr intptr_t kInlineCapacityInBytes = 16;
bool InRange(intptr_t offset) const {
if (offset < 0) {
"Fatal error in BitmapBuilder::InRange :"
" invalid bit_offset, %" Pd "\n",
return (offset < length_);
bool InBackingStore(intptr_t bit_offset) {
intptr_t byte_offset = bit_offset >> kBitsPerByteLog2;
return byte_offset < data_size_in_bytes_;
uint8_t* BackingStore() {
return data_size_in_bytes_ == kInlineCapacityInBytes ? &data_.inline_[0]
: data_.ptr_;
const uint8_t* BackingStore() const {
return data_size_in_bytes_ == kInlineCapacityInBytes ? &data_.inline_[0]
: data_.ptr_;
static uint8_t* AllocBackingStore(intptr_t size_in_bytes) {
return ThreadState::Current()->zone()->Alloc<uint8_t>(size_in_bytes);
// Get/Set a bit that is known to be covered by the backing store.
bool GetBit(intptr_t bit_offset) const;
void SetBit(intptr_t bit_offset, bool value);
intptr_t length_;
// Backing store for the bitmap. Reading bits beyond the backing store
// (up to length_) is allowed and they are assumed to be false.
intptr_t data_size_in_bytes_;
union {
uint8_t* ptr_;
uint8_t inline_[kInlineCapacityInBytes];
} data_;
} // namespace dart