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![Ryan Macnak](/assets/img/avatar_default.png)
TEST=local build Change-Id: I9503dfbb1b9ba6ef2b5fb8423c13d5066e5af98b Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/206140 Commit-Queue: Ryan Macnak <rmacnak@google.com> Reviewed-by: Tess Strickland <sstrickl@google.com>
108 lines
3.3 KiB
C++
108 lines
3.3 KiB
C++
// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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#ifndef RUNTIME_VM_BITMAP_H_
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#define RUNTIME_VM_BITMAP_H_
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#include "vm/allocation.h"
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#include "vm/datastream.h"
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#include "vm/thread_state.h"
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#include "vm/zone.h"
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namespace dart {
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// BitmapBuilder is used to build a bitmap. The implementation is optimized
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// for a dense set of small bit maps without a fixed upper bound (e.g: a
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// pointer map description of a stack).
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class BitmapBuilder : public ZoneAllocated {
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public:
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BitmapBuilder() : length_(0), data_size_in_bytes_(kInlineCapacityInBytes) {
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memset(data_.inline_, 0, data_size_in_bytes_);
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}
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BitmapBuilder(const BitmapBuilder& other)
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: ZoneAllocated(),
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length_(other.length_),
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data_size_in_bytes_(other.data_size_in_bytes_) {
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if (data_size_in_bytes_ == kInlineCapacityInBytes) {
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memmove(data_.inline_, other.data_.inline_, kInlineCapacityInBytes);
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} else {
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data_.ptr_ = AllocBackingStore(data_size_in_bytes_);
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memmove(data_.ptr_, other.data_.ptr_, data_size_in_bytes_);
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}
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}
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intptr_t Length() const { return length_; }
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void SetLength(intptr_t length);
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// Get/Set individual bits in the bitmap, setting bits beyond the bitmap's
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// length increases the length and expands the underlying bitmap if
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// needed.
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bool Get(intptr_t bit_offset) const;
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void Set(intptr_t bit_offset, bool value);
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// Return the bit offset of the highest bit set.
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intptr_t Maximum() const;
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// Return the bit offset of the lowest bit set.
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intptr_t Minimum() const;
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// Sets min..max (inclusive) to value.
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void SetRange(intptr_t min, intptr_t max, bool value);
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void Print() const;
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void AppendAsBytesTo(BaseWriteStream* stream) const;
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private:
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static constexpr intptr_t kIncrementSizeInBytes = 16;
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static constexpr intptr_t kInlineCapacityInBytes = 16;
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bool InRange(intptr_t offset) const {
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if (offset < 0) {
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FATAL1(
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"Fatal error in BitmapBuilder::InRange :"
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" invalid bit_offset, %" Pd "\n",
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offset);
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}
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return (offset < length_);
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}
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bool InBackingStore(intptr_t bit_offset) {
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intptr_t byte_offset = bit_offset >> kBitsPerByteLog2;
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return byte_offset < data_size_in_bytes_;
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}
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uint8_t* BackingStore() {
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return data_size_in_bytes_ == kInlineCapacityInBytes ? &data_.inline_[0]
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: data_.ptr_;
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}
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const uint8_t* BackingStore() const {
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return data_size_in_bytes_ == kInlineCapacityInBytes ? &data_.inline_[0]
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: data_.ptr_;
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}
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static uint8_t* AllocBackingStore(intptr_t size_in_bytes) {
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return ThreadState::Current()->zone()->Alloc<uint8_t>(size_in_bytes);
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}
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// Get/Set a bit that is known to be covered by the backing store.
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bool GetBit(intptr_t bit_offset) const;
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void SetBit(intptr_t bit_offset, bool value);
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intptr_t length_;
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// Backing store for the bitmap. Reading bits beyond the backing store
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// (up to length_) is allowed and they are assumed to be false.
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intptr_t data_size_in_bytes_;
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union {
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uint8_t* ptr_;
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uint8_t inline_[kInlineCapacityInBytes];
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} data_;
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};
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} // namespace dart
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#endif // RUNTIME_VM_BITMAP_H_
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