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// Copyright 2017 The Dawn Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "dawn_native/opengl/BufferGL.h"
#include "dawn_native/CommandBuffer.h"
#include "dawn_native/opengl/DeviceGL.h"
namespace dawn_native::opengl {
// Buffer
// static
ResultOrError<Ref<Buffer>> Buffer::CreateInternalBuffer(Device* device,
const BufferDescriptor* descriptor,
bool shouldLazyClear) {
Ref<Buffer> buffer = AcquireRef(new Buffer(device, descriptor, shouldLazyClear));
if (descriptor->mappedAtCreation) {
DAWN_TRY(buffer->MapAtCreationInternal());
}
return std::move(buffer);
}
Buffer::Buffer(Device* device, const BufferDescriptor* descriptor)
: BufferBase(device, descriptor) {
// Allocate at least 4 bytes so clamped accesses are always in bounds.
mAllocatedSize = std::max(GetSize(), uint64_t(4u));
device->gl.GenBuffers(1, &mBuffer);
device->gl.BindBuffer(GL_ARRAY_BUFFER, mBuffer);
// The buffers with mappedAtCreation == true will be initialized in
// BufferBase::MapAtCreation().
if (device->IsToggleEnabled(Toggle::NonzeroClearResourcesOnCreationForTesting) &&
!descriptor->mappedAtCreation) {
std::vector<uint8_t> clearValues(mAllocatedSize, 1u);
device->gl.BufferData(GL_ARRAY_BUFFER, mAllocatedSize, clearValues.data(),
GL_STATIC_DRAW);
} else {
// Buffers start zeroed if you pass nullptr to glBufferData.
device->gl.BufferData(GL_ARRAY_BUFFER, mAllocatedSize, nullptr, GL_STATIC_DRAW);
}
}
Buffer::Buffer(Device* device, const BufferDescriptor* descriptor, bool shouldLazyClear)
: Buffer(device, descriptor) {
if (!shouldLazyClear) {
SetIsDataInitialized();
}
}
Buffer::~Buffer() = default;
GLuint Buffer::GetHandle() const {
return mBuffer;
}
bool Buffer::EnsureDataInitialized() {
if (!NeedsInitialization()) {
return false;
}
InitializeToZero();
return true;
}
bool Buffer::EnsureDataInitializedAsDestination(uint64_t offset, uint64_t size) {
if (!NeedsInitialization()) {
return false;
}
if (IsFullBufferRange(offset, size)) {
SetIsDataInitialized();
return false;
}
InitializeToZero();
return true;
}
bool Buffer::EnsureDataInitializedAsDestination(const CopyTextureToBufferCmd* copy) {
if (!NeedsInitialization()) {
return false;
}
if (IsFullBufferOverwrittenInTextureToBufferCopy(copy)) {
SetIsDataInitialized();
return false;
}
InitializeToZero();
return true;
}
void Buffer::InitializeToZero() {
ASSERT(NeedsInitialization());
const uint64_t size = GetAllocatedSize();
Device* device = ToBackend(GetDevice());
const std::vector<uint8_t> clearValues(size, 0u);
device->gl.BindBuffer(GL_ARRAY_BUFFER, mBuffer);
device->gl.BufferSubData(GL_ARRAY_BUFFER, 0, size, clearValues.data());
device->IncrementLazyClearCountForTesting();
SetIsDataInitialized();
}
bool Buffer::IsCPUWritableAtCreation() const {
// TODO(enga): All buffers in GL can be mapped. Investigate if mapping them will cause the
// driver to migrate it to shared memory.
return true;
}
MaybeError Buffer::MapAtCreationImpl() {
const OpenGLFunctions& gl = ToBackend(GetDevice())->gl;
gl.BindBuffer(GL_ARRAY_BUFFER, mBuffer);
mMappedData = gl.MapBufferRange(GL_ARRAY_BUFFER, 0, GetSize(), GL_MAP_WRITE_BIT);
return {};
}
MaybeError Buffer::MapAsyncImpl(wgpu::MapMode mode, size_t offset, size_t size) {
const OpenGLFunctions& gl = ToBackend(GetDevice())->gl;
// It is an error to map an empty range in OpenGL. We always have at least a 4-byte buffer
// so we extend the range to be 4 bytes.
if (size == 0) {
if (offset != 0) {
offset -= 4;
}
size = 4;
}
EnsureDataInitialized();
// This does GPU->CPU synchronization, we could require a high
// version of OpenGL that would let us map the buffer unsynchronized.
gl.BindBuffer(GL_ARRAY_BUFFER, mBuffer);
void* mappedData = nullptr;
if (mode & wgpu::MapMode::Read) {
mappedData = gl.MapBufferRange(GL_ARRAY_BUFFER, offset, size, GL_MAP_READ_BIT);
} else {
ASSERT(mode & wgpu::MapMode::Write);
mappedData = gl.MapBufferRange(GL_ARRAY_BUFFER, offset, size, GL_MAP_WRITE_BIT);
}
// The frontend asks that the pointer returned by GetMappedPointerImpl is from the start of
// the resource but OpenGL gives us the pointer at offset. Remove the offset.
mMappedData = static_cast<uint8_t*>(mappedData) - offset;
return {};
}
void* Buffer::GetMappedPointerImpl() {
// The mapping offset has already been removed.
return mMappedData;
}
void Buffer::UnmapImpl() {
const OpenGLFunctions& gl = ToBackend(GetDevice())->gl;
gl.BindBuffer(GL_ARRAY_BUFFER, mBuffer);
gl.UnmapBuffer(GL_ARRAY_BUFFER);
mMappedData = nullptr;
}
void Buffer::DestroyImpl() {
BufferBase::DestroyImpl();
ToBackend(GetDevice())->gl.DeleteBuffers(1, &mBuffer);
mBuffer = 0;
}
} // namespace dawn_native::opengl