blob: f0304d015a9aa303539c76a5bdb365cc5a04650c [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.
#ifndef VM_BITMAP_H_
#define VM_BITMAP_H_
#include "vm/allocation.h"
#include "vm/isolate.h"
#include "vm/zone.h"
namespace dart {
// Forward declarations.
class RawStackmap;
class Stackmap;
// 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 {
public:
BitmapBuilder()
: length_(0),
data_size_in_bytes_(kInitialSizeInBytes),
data_(Isolate::Current()->current_zone()->Alloc<uint8_t>(
kInitialSizeInBytes)) {
memset(data_, 0, kInitialSizeInBytes);
}
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);
private:
static const intptr_t kInitialSizeInBytes = 16;
static const intptr_t kIncrementSizeInBytes = 16;
bool InRange(intptr_t offset) const {
return (offset >= 0) && (offset < length_);
}
// 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_;
uint8_t* data_;
DISALLOW_COPY_AND_ASSIGN(BitmapBuilder);
};
} // namespace dart
#endif // VM_BITMAP_H_