host/compressedTextureFormats/AstcCpuDecompressorImpl.cpp - platform/hardware/google/gfxstream - Git at Google

 // Copyright 2022 The Android Open Source Project
 //
 // 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 <array>
 #include <future>
 #include <unordered_map>

 #include "AstcCpuDecompressor.h"
 #include "astcenc.h"

 namespace gfxstream {
 namespace vk {
 namespace {

 constexpr uint32_t kNumThreads = 2;

 const astcenc_swizzle kSwizzle = {ASTCENC_SWZ_R, ASTCENC_SWZ_G, ASTCENC_SWZ_B, ASTCENC_SWZ_A};

 // Used by std::unique_ptr to release the context when the pointer is destroyed
 struct AstcencContextDeleter {
     void operator()(astcenc_context* c) { astcenc_context_free(c); }
 };

 using AstcencContextUniquePtr = std::unique_ptr<astcenc_context, AstcencContextDeleter>;

 // Creates a new astcenc_context and wraps it in a smart pointer.
 // It is not needed to call astcenc_context_free() on the returned pointer.
 // blockWith, blockSize: ASTC block size for the context
 // Error: (output param) Where to put the error status. Must not be null.
 // Returns nullptr in case of error.
 AstcencContextUniquePtr makeDecoderContext(uint32_t blockWidth, uint32_t blockHeight,
                                            astcenc_error* error) {
     astcenc_config config = {};
     *error =
         // TODO(gregschlom): Do we need to pass ASTCENC_PRF_LDR_SRGB here?
         astcenc_config_init(ASTCENC_PRF_LDR, blockWidth, blockHeight, 1, ASTCENC_PRE_FASTEST,
                             ASTCENC_FLG_DECOMPRESS_ONLY, &config);
     if (*error != ASTCENC_SUCCESS) {
         return nullptr;
     }

     astcenc_context* context;
     *error = astcenc_context_alloc(&config, kNumThreads, &context);
     if (*error != ASTCENC_SUCCESS) {
         return nullptr;
     }
     return AstcencContextUniquePtr(context);
 }


 #if !defined(__clang__) && defined(_MSC_VER)
 // AVX2 support detection for Visual Studio
 #include <intrin.h>
 bool cpuSupportsAvx2()
 {
     int data[4];
     __cpuid(data, 0);
     if (data[0] >= 7) {
         __cpuidex(data, 7, 0);
         return data[1] & (1 << 5);  // AVX2 = Bank 7, EBX, bit 5
     }
     return false;
 }
 #elif defined(__aarch64__)
 bool cpuSupportsAvx2()
 {
     return false;
 }
 #else
 // AVX2 support detection for GCC and Clang
 #include <cpuid.h>
 bool cpuSupportsAvx2()
 {
     unsigned int data[4];
     if (__get_cpuid_count(7, 0, &data[0], &data[1], &data[2], &data[3])) {
         return data[1] & (1 << 5);  // AVX2 = Bank 7, EBX, bit 5
     }
     return false;
 }
 #endif

 // Returns whether the ASTC decoder can be used on this machine. It might not be available if the
 // CPU doesn't support AVX2 instructions for example. Since this call is a bit expensive and never
 // changes, the result should be cached.
 bool isAstcDecoderAvailable() {
     if (!cpuSupportsAvx2()) return false;
     astcenc_error error;
     // Try getting an arbitrary context. If it works, the decoder is available.
     auto context = makeDecoderContext(5, 5, &error);
     return context != nullptr;
 }

 // Caches and manages astcenc_context objects.
 //
 // Each context is fairly large (around 30 MB) and takes a while to construct, so it's important to
 // reuse them as much as possible.
 //
 // While context objects can be reused across multiple threads, they must be used sequentially. To
 // avoid having to lock and manage access between threads, we keep one cache per thread. This avoids
 // any concurrency issues, at the cost of extra memory.
 //
 // Currently, there is no eviction strategy. Each cache could grow to a maximum of ~400 MB in size
 // since they are 13 possible ASTC block sizes.
 //
 // Thread-safety: not thread safe.
 class AstcDecoderContextCache {
    public:
     // Returns a context object for a given ASTC block size, along with the error code if the
     // context initialization failed.
     // In this case, the context will be null, and the status code will be non-zero.
     std::pair<astcenc_context*, astcenc_error> get(uint32_t blockWidth, uint32_t blockHeight) {
         Value& value = mContexts[{blockWidth, blockHeight}];
         if (value.context == nullptr) {
             value.context = makeDecoderContext(blockWidth, blockHeight, &value.error);
         }
         return {value.context.get(), value.error};
     }

    private:
     // Holds the data we use as the cache key
     struct Key {
         uint32_t blockWidth;
         uint32_t blockHeight;

         bool operator==(const Key& other) const {
             return blockWidth == other.blockWidth && blockHeight == other.blockHeight;
         }
     };

     struct Value {
         AstcencContextUniquePtr context = nullptr;
         astcenc_error error = ASTCENC_SUCCESS;
     };

     // Computes the hash of a Key
     struct KeyHash {
         std::size_t operator()(const Key& k) const {
             // blockWidth and blockHeight are < 256 (actually, < 16), so this is safe
             return k.blockWidth << 8 | k.blockHeight;
         }
     };

     std::unordered_map<Key, Value, KeyHash> mContexts;
 };

 // Thread-safety: all public methods are thread-safe
 class WorkerThread {
    public:
     explicit WorkerThread() : mThread(&WorkerThread::main, this) {}

     // Terminates the thread. Call wait() to wait until the thread fully exits.
     void terminate() {
         std::lock_guard lock(mWorkerMutex);
         mTerminated = true;
         mWorkerCondition.notify_one();
     }

     // Blocks until the thread exits.
     void wait() { mThread.join(); }

     std::future<astcenc_error> decompress(astcenc_context* context, uint32_t threadIndex,
                                           const uint8_t* data, size_t dataLength,
                                           astcenc_image* image) {
         std::lock_guard lock(mWorkerMutex);
         mTask = std::packaged_task<astcenc_error()>{[=] {
             return astcenc_decompress_image(context, data, dataLength, image, &kSwizzle,
                                             threadIndex);
         }};
         mWorkerCondition.notify_one();
         return mTask.get_future();
     }

    private:
     // Thread's main loop
     void main() {
         while (true) {
             std::packaged_task<astcenc_error()> task;
             {
                 std::unique_lock lock(mWorkerMutex);
                 mWorkerCondition.wait(lock, [this] { return mTask.valid() || mTerminated; });
                 if (mTerminated) return;
                 task = std::move(mTask);
             }
             task();
         }
     }

     bool mTerminated = false;
     std::condition_variable mWorkerCondition = {};  // Signals availability of work
     std::mutex mWorkerMutex = {};                   // Mutex used with mWorkerCondition.
     std::packaged_task<astcenc_error()> mTask = {};
     std::thread mThread = {};
 };

 // Performs ASTC decompression of an image on the CPU
 class AstcCpuDecompressorImpl : public AstcCpuDecompressor {
    public:
     AstcCpuDecompressorImpl()
         : AstcCpuDecompressor(), mContextCache(std::make_unique<AstcDecoderContextCache>()) {}

     ~AstcCpuDecompressorImpl() override {
         // Stop the worker threads, otherwise the process would hang upon exit.
         std::lock_guard global_lock(mMutex);
         for (auto& worker : mWorkerThreads) {
             worker.terminate();
             worker.wait();
         }
     }

     bool available() const override {
         static bool available = isAstcDecoderAvailable();
         return available;
     }

     int32_t decompress(const uint32_t imgWidth, const uint32_t imgHeight, const uint32_t blockWidth,
                        const uint32_t blockHeight, const uint8_t* astcData, size_t astcDataLength,
                        uint8_t* output) override {
         std::array<std::future<astcenc_error>, kNumThreads> futures;

         std::lock_guard global_lock(mMutex);

         auto [context, context_status] = mContextCache->get(blockWidth, blockHeight);
         if (context_status != ASTCENC_SUCCESS) return context_status;

         astcenc_image image = {
             .dim_x = imgWidth,
             .dim_y = imgHeight,
             .dim_z = 1,
             .data_type = ASTCENC_TYPE_U8,
             .data = reinterpret_cast<void**>(&output),
         };

         for (uint32_t i = 0; i < kNumThreads; ++i) {
             futures[i] = mWorkerThreads[i].decompress(context, i, astcData, astcDataLength, &image);
         }

         astcenc_error result = ASTCENC_SUCCESS;

         // Wait for all threads to be done
         for (auto& future : futures) {
             astcenc_error status = future.get();
             if (status != ASTCENC_SUCCESS) {
                 result = status;
             }
         }

         astcenc_decompress_reset(context);

         return result;
     }

     const char* getStatusString(int32_t statusCode) const override {
         const char* msg = astcenc_get_error_string((astcenc_error)statusCode);
         return msg ? msg : "ASTCENC_UNKNOWN_STATUS";
     }

    private:
     std::unique_ptr<AstcDecoderContextCache> mContextCache;
     std::mutex mMutex;  // Locked while calling `decompress()`
     std::array<WorkerThread, kNumThreads> mWorkerThreads;
 };

 }  // namespace

 AstcCpuDecompressor& AstcCpuDecompressor::get() {
     static AstcCpuDecompressorImpl instance;
     return instance;
 }

 }  // namespace vk
 }  // namespace gfxstream
	// Copyright 2022 The Android Open Source Project
	//
	// 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 <array>
	#include <future>
	#include <unordered_map>

	#include "AstcCpuDecompressor.h"
	#include "astcenc.h"

	namespace gfxstream {
	namespace vk {
	namespace {

	constexpr uint32_t kNumThreads = 2;

	const astcenc_swizzle kSwizzle = {ASTCENC_SWZ_R, ASTCENC_SWZ_G, ASTCENC_SWZ_B, ASTCENC_SWZ_A};

	// Used by std::unique_ptr to release the context when the pointer is destroyed
	struct AstcencContextDeleter {
	void operator()(astcenc_context* c) { astcenc_context_free(c); }
	};

	using AstcencContextUniquePtr = std::unique_ptr<astcenc_context, AstcencContextDeleter>;

	// Creates a new astcenc_context and wraps it in a smart pointer.
	// It is not needed to call astcenc_context_free() on the returned pointer.
	// blockWith, blockSize: ASTC block size for the context
	// Error: (output param) Where to put the error status. Must not be null.
	// Returns nullptr in case of error.
	AstcencContextUniquePtr makeDecoderContext(uint32_t blockWidth, uint32_t blockHeight,
	astcenc_error* error) {
	astcenc_config config = {};
	*error =
	// TODO(gregschlom): Do we need to pass ASTCENC_PRF_LDR_SRGB here?
	astcenc_config_init(ASTCENC_PRF_LDR, blockWidth, blockHeight, 1, ASTCENC_PRE_FASTEST,
	ASTCENC_FLG_DECOMPRESS_ONLY, &config);
	if (*error != ASTCENC_SUCCESS) {
	return nullptr;
	}

	astcenc_context* context;
	*error = astcenc_context_alloc(&config, kNumThreads, &context);
	if (*error != ASTCENC_SUCCESS) {
	return nullptr;
	}
	return AstcencContextUniquePtr(context);
	}


	#if !defined(__clang__) && defined(_MSC_VER)
	// AVX2 support detection for Visual Studio
	#include <intrin.h>
	bool cpuSupportsAvx2()
	{
	int data[4];
	__cpuid(data, 0);
	if (data[0] >= 7) {
	__cpuidex(data, 7, 0);
	return data[1] & (1 << 5); // AVX2 = Bank 7, EBX, bit 5
	}
	return false;
	}
	#elif defined(__aarch64__)
	bool cpuSupportsAvx2()
	{
	return false;
	}
	#else
	// AVX2 support detection for GCC and Clang
	#include <cpuid.h>
	bool cpuSupportsAvx2()
	{
	unsigned int data[4];
	if (__get_cpuid_count(7, 0, &data[0], &data[1], &data[2], &data[3])) {
	return data[1] & (1 << 5); // AVX2 = Bank 7, EBX, bit 5
	}
	return false;
	}
	#endif

	// Returns whether the ASTC decoder can be used on this machine. It might not be available if the
	// CPU doesn't support AVX2 instructions for example. Since this call is a bit expensive and never
	// changes, the result should be cached.
	bool isAstcDecoderAvailable() {
	if (!cpuSupportsAvx2()) return false;
	astcenc_error error;
	// Try getting an arbitrary context. If it works, the decoder is available.
	auto context = makeDecoderContext(5, 5, &error);
	return context != nullptr;
	}

	// Caches and manages astcenc_context objects.
	//
	// Each context is fairly large (around 30 MB) and takes a while to construct, so it's important to
	// reuse them as much as possible.
	//
	// While context objects can be reused across multiple threads, they must be used sequentially. To
	// avoid having to lock and manage access between threads, we keep one cache per thread. This avoids
	// any concurrency issues, at the cost of extra memory.
	//
	// Currently, there is no eviction strategy. Each cache could grow to a maximum of ~400 MB in size
	// since they are 13 possible ASTC block sizes.
	//
	// Thread-safety: not thread safe.
	class AstcDecoderContextCache {
	public:
	// Returns a context object for a given ASTC block size, along with the error code if the
	// context initialization failed.
	// In this case, the context will be null, and the status code will be non-zero.
	std::pair<astcenc_context*, astcenc_error> get(uint32_t blockWidth, uint32_t blockHeight) {
	Value& value = mContexts[{blockWidth, blockHeight}];
	if (value.context == nullptr) {
	value.context = makeDecoderContext(blockWidth, blockHeight, &value.error);
	}
	return {value.context.get(), value.error};
	}

	private:
	// Holds the data we use as the cache key
	struct Key {
	uint32_t blockWidth;
	uint32_t blockHeight;

	bool operator==(const Key& other) const {
	return blockWidth == other.blockWidth && blockHeight == other.blockHeight;
	}
	};

	struct Value {
	AstcencContextUniquePtr context = nullptr;
	astcenc_error error = ASTCENC_SUCCESS;
	};

	// Computes the hash of a Key
	struct KeyHash {
	std::size_t operator()(const Key& k) const {
	// blockWidth and blockHeight are < 256 (actually, < 16), so this is safe
	return k.blockWidth << 8 \| k.blockHeight;
	}
	};

	std::unordered_map<Key, Value, KeyHash> mContexts;
	};

	// Thread-safety: all public methods are thread-safe
	class WorkerThread {
	public:
	explicit WorkerThread() : mThread(&WorkerThread::main, this) {}

	// Terminates the thread. Call wait() to wait until the thread fully exits.
	void terminate() {
	std::lock_guard lock(mWorkerMutex);
	mTerminated = true;
	mWorkerCondition.notify_one();
	}

	// Blocks until the thread exits.
	void wait() { mThread.join(); }

	std::future<astcenc_error> decompress(astcenc_context* context, uint32_t threadIndex,
	const uint8_t* data, size_t dataLength,
	astcenc_image* image) {
	std::lock_guard lock(mWorkerMutex);
	mTask = std::packaged_task<astcenc_error()>{[=] {
	return astcenc_decompress_image(context, data, dataLength, image, &kSwizzle,
	threadIndex);
	}};
	mWorkerCondition.notify_one();
	return mTask.get_future();
	}

	private:
	// Thread's main loop
	void main() {
	while (true) {
	std::packaged_task<astcenc_error()> task;
	{
	std::unique_lock lock(mWorkerMutex);
	mWorkerCondition.wait(lock, [this] { return mTask.valid() \|\| mTerminated; });
	if (mTerminated) return;
	task = std::move(mTask);
	}
	task();
	}
	}

	bool mTerminated = false;
	std::condition_variable mWorkerCondition = {}; // Signals availability of work
	std::mutex mWorkerMutex = {}; // Mutex used with mWorkerCondition.
	std::packaged_task<astcenc_error()> mTask = {};
	std::thread mThread = {};
	};

	// Performs ASTC decompression of an image on the CPU
	class AstcCpuDecompressorImpl : public AstcCpuDecompressor {
	public:
	AstcCpuDecompressorImpl()
	: AstcCpuDecompressor(), mContextCache(std::make_unique<AstcDecoderContextCache>()) {}

	~AstcCpuDecompressorImpl() override {
	// Stop the worker threads, otherwise the process would hang upon exit.
	std::lock_guard global_lock(mMutex);
	for (auto& worker : mWorkerThreads) {
	worker.terminate();
	worker.wait();
	}
	}

	bool available() const override {
	static bool available = isAstcDecoderAvailable();
	return available;
	}

	int32_t decompress(const uint32_t imgWidth, const uint32_t imgHeight, const uint32_t blockWidth,
	const uint32_t blockHeight, const uint8_t* astcData, size_t astcDataLength,
	uint8_t* output) override {
	std::array<std::future<astcenc_error>, kNumThreads> futures;

	std::lock_guard global_lock(mMutex);

	auto [context, context_status] = mContextCache->get(blockWidth, blockHeight);
	if (context_status != ASTCENC_SUCCESS) return context_status;

	astcenc_image image = {
	.dim_x = imgWidth,
	.dim_y = imgHeight,
	.dim_z = 1,
	.data_type = ASTCENC_TYPE_U8,
	.data = reinterpret_cast<void**>(&output),
	};

	for (uint32_t i = 0; i < kNumThreads; ++i) {
	futures[i] = mWorkerThreads[i].decompress(context, i, astcData, astcDataLength, &image);
	}

	astcenc_error result = ASTCENC_SUCCESS;

	// Wait for all threads to be done
	for (auto& future : futures) {
	astcenc_error status = future.get();
	if (status != ASTCENC_SUCCESS) {
	result = status;
	}
	}

	astcenc_decompress_reset(context);

	return result;
	}

	const char* getStatusString(int32_t statusCode) const override {
	const char* msg = astcenc_get_error_string((astcenc_error)statusCode);
	return msg ? msg : "ASTCENC_UNKNOWN_STATUS";
	}

	private:
	std::unique_ptr<AstcDecoderContextCache> mContextCache;
	std::mutex mMutex; // Locked while calling `decompress()`
	std::array<WorkerThread, kNumThreads> mWorkerThreads;
	};

	} // namespace

	AstcCpuDecompressor& AstcCpuDecompressor::get() {
	static AstcCpuDecompressorImpl instance;
	return instance;
	}

	} // namespace vk
	} // namespace gfxstream