1 files changed, 179 insertions, 0 deletions
diff --git a/gfx/angle/checkout/src/common/MemoryBuffer.cpp b/gfx/angle/checkout/src/common/MemoryBuffer.cpp
new file mode 100644
index 0000000000..aadffe8bbe
--- /dev/null
+++ b/gfx/angle/checkout/src/common/MemoryBuffer.cpp
@@ -0,0 +1,179 @@
+//
+// Copyright 2014 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+
+#include "common/MemoryBuffer.h"
+
+#include <algorithm>
+#include <cstdlib>
+
+#include "common/debug.h"
+
+namespace angle
+{
+
+// MemoryBuffer implementation.
+MemoryBuffer::~MemoryBuffer()
+{
+    if (mData)
+    {
+        free(mData);
+        mData = nullptr;
+    }
+}
+
+bool MemoryBuffer::resize(size_t size)
+{
+    if (size == 0)
+    {
+        if (mData)
+        {
+            free(mData);
+            mData = nullptr;
+        }
+        mSize = 0;
+        return true;
+    }
+
+    if (size == mSize)
+    {
+        return true;
+    }
+
+    // Only reallocate if the size has changed.
+    uint8_t *newMemory = static_cast<uint8_t *>(malloc(sizeof(uint8_t) * size));
+    if (newMemory == nullptr)
+    {
+        return false;
+    }
+
+    if (mData)
+    {
+        // Copy the intersection of the old data and the new data
+        std::copy(mData, mData + std::min(mSize, size), newMemory);
+        free(mData);
+    }
+
+    mData = newMemory;
+    mSize = size;
+
+    return true;
+}
+
+void MemoryBuffer::fill(uint8_t datum)
+{
+    if (!empty())
+    {
+        std::fill(mData, mData + mSize, datum);
+    }
+}
+
+MemoryBuffer::MemoryBuffer(MemoryBuffer &&other) : MemoryBuffer()
+{
+    *this = std::move(other);
+}
+
+MemoryBuffer &MemoryBuffer::operator=(MemoryBuffer &&other)
+{
+    std::swap(mSize, other.mSize);
+    std::swap(mData, other.mData);
+    return *this;
+}
+
+namespace
+{
+static constexpr uint32_t kDefaultScratchBufferLifetime = 1000u;
+
+}  // anonymous namespace
+
+// ScratchBuffer implementation.
+ScratchBuffer::ScratchBuffer() : ScratchBuffer(kDefaultScratchBufferLifetime) {}
+
+ScratchBuffer::ScratchBuffer(uint32_t lifetime) : mLifetime(lifetime), mResetCounter(lifetime) {}
+
+ScratchBuffer::~ScratchBuffer() {}
+
+ScratchBuffer::ScratchBuffer(ScratchBuffer &&other)
+{
+    *this = std::move(other);
+}
+
+ScratchBuffer &ScratchBuffer::operator=(ScratchBuffer &&other)
+{
+    std::swap(mLifetime, other.mLifetime);
+    std::swap(mResetCounter, other.mResetCounter);
+    std::swap(mScratchMemory, other.mScratchMemory);
+    return *this;
+}
+
+bool ScratchBuffer::get(size_t requestedSize, MemoryBuffer **memoryBufferOut)
+{
+    return getImpl(requestedSize, memoryBufferOut, Optional<uint8_t>::Invalid());
+}
+
+bool ScratchBuffer::getInitialized(size_t requestedSize,
+                                   MemoryBuffer **memoryBufferOut,
+                                   uint8_t initValue)
+{
+    return getImpl(requestedSize, memoryBufferOut, Optional<uint8_t>(initValue));
+}
+
+bool ScratchBuffer::getImpl(size_t requestedSize,
+                            MemoryBuffer **memoryBufferOut,
+                            Optional<uint8_t> initValue)
+{
+    if (mScratchMemory.size() == requestedSize)
+    {
+        mResetCounter    = mLifetime;
+        *memoryBufferOut = &mScratchMemory;
+        return true;
+    }
+
+    if (mScratchMemory.size() > requestedSize)
+    {
+        tick();
+    }
+
+    if (mScratchMemory.size() < requestedSize)
+    {
+        if (!mScratchMemory.resize(requestedSize))
+        {
+            return false;
+        }
+        mResetCounter = mLifetime;
+        if (initValue.valid())
+        {
+            mScratchMemory.fill(initValue.value());
+        }
+    }
+
+    ASSERT(mScratchMemory.size() >= requestedSize);
+
+    *memoryBufferOut = &mScratchMemory;
+    return true;
+}
+
+void ScratchBuffer::tick()
+{
+    if (mResetCounter > 0)
+    {
+        --mResetCounter;
+        if (mResetCounter == 0)
+        {
+            clear();
+        }
+    }
+}
+
+void ScratchBuffer::clear()
+{
+    mResetCounter = mLifetime;
+    if (mScratchMemory.size() > 0)
+    {
+        mScratchMemory.clear();
+    }
+}
+
+}  // namespace angle