Initial work

external/android-emugl/shared/OpenglCodecCommon/ProtocolUtils.h

@@ -0,0 +1,193 @@
+#ifndef EMUGL_PROTOCOL_UTILS_H
+#define EMUGL_PROTOCOL_UTILS_H
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+namespace emugl {
+
+// Helper macro
+#define COMPILE_ASSERT(cond)  static char kAssert##__LINE__[1 - 2 * !(cond)] __attribute__((unused)) = { 0 }
+
+// Helper template: is_pointer.
+// is_pointer<T>::value is true iff |T| is a pointer type.
+template <typename T> struct is_pointer {
+    static const bool value = false;
+};
+
+template <typename T> struct is_pointer<T*> {
+    static const bool value = true;
+};
+
+// A helper template to extract values form the wire protocol stream
+// and convert them to appropriate host values.
+//
+// The wire protocol uses 32-bit exclusively when transferring
+// GLintptr or GLsizei values, as well as opaque handles like GLeglImage,
+// from the guest (even when the guest is 64-bit).
+//
+// The corresponding host definitions depend on the host bitness. For
+// example, GLintptr is 64-bit on linux-x86_64. The following is a set
+// of templates that can simplify the conversion of protocol values
+// into host ones.
+//
+// The most important one is:
+//
+//     unpack<HOST_TYPE,SIZE_TYPE>(const void* ptr)
+//
+// Which reads bytes from |ptr|, using |SIZE_TYPE| as the underlying
+// sized-integer specifier (e.g. 'uint32_t'), and converting the result
+// into a |HOST_TYPE| value. For example:
+//
+//     unpack<EGLImage,uint32_t>(ptr + 12);
+//
+// will read a 4-byte value from |ptr + 12| and convert it into
+// an EGLImage, which is a host void*. The template detects host
+// pointer types to perform proper type casting.
+//
+// TODO(digit): Add custom unpackers to handle generic opaque void* values.
+//              and map them to unique 32-bit values.
+
+template <typename T, typename S, bool IS_POINTER>
+struct UnpackerT {};
+
+template <typename T, typename S>
+struct UnpackerT<T,S,false> {
+    static inline T unpack(const void* ptr) {
+        COMPILE_ASSERT(sizeof(T) == sizeof(S));
+        return (T)(*(S*)(ptr));
+    }
+};
+
+template <typename T, typename S>
+struct UnpackerT<T,S,true> {
+    static inline T unpack(const void* ptr) {
+        return (T)(uintptr_t)(*(S*)(ptr));
+    }
+};
+
+template <>
+struct UnpackerT<float,uint32_t,false> {
+    static inline float unpack(const void* ptr) {
+        union {
+            float f;
+            uint32_t u;
+        } v;
+        v.u = *(uint32_t*)(ptr);
+        return v.f;
+    }
+};
+
+template <>
+struct UnpackerT<double,uint64_t,false> {
+    static inline double unpack(const void* ptr) {
+        union {
+            double d;
+            uint32_t u;
+        } v;
+        v.u = *(uint64_t*)(ptr);
+        return v.d;
+    }
+};
+
+template <>
+struct UnpackerT<ssize_t,uint32_t,false> {
+    static inline ssize_t unpack(const void* ptr) {
+        return (ssize_t)*(int32_t*)(ptr);
+    }
+};
+
+template <typename T, typename S>
+inline T Unpack(const void* ptr) {
+    return UnpackerT<T, S, is_pointer<T>::value>::unpack(ptr);
+}
+
+// Helper class used to ensure input buffers passed to EGL/GL functions
+// are properly aligned (preventing crashes with some backends).
+// Usage example:
+//
+//    InputBuffer inputBuffer(ptr, size);
+//    glDoStuff(inputBuffer.get());
+//
+// inputBuffer.get() will return the original value of |ptr| if it was
+// aligned on an 8-byte boundary. Otherwise, it will return the address
+// of an aligned heap-allocated copy of the original |size| bytes starting
+// from |ptr|. The heap block is released at scope exit.
+class InputBuffer {
+public:
+    InputBuffer(const void* input, size_t size, size_t align = 8) :
+            mBuff(input), mIsCopy(false) {
+        if (((uintptr_t)input & (align - 1U)) != 0) {
+            void* newBuff = malloc(size);
+            memcpy(newBuff, input, size);
+            mBuff = newBuff;
+            mIsCopy = true;
+        }
+    }
+
+    ~InputBuffer() {
+        if (mIsCopy) {
+            free((void*)mBuff);
+        }
+    }
+
+    const void* get() const {
+        return mBuff;
+    }
+
+private:
+    const void* mBuff;
+    bool mIsCopy;
+};
+
+// Helper class used to ensure that output buffers passed to EGL/GL functions
+// are aligned on 8-byte addresses.
+// Usage example:
+//
+//    ptr = stream->alloc(size);
+//    OutputBuffer outputBuffer(ptr, size);
+//    glGetStuff(outputBuffer.get());
+//    outputBuffer.flush();
+//
+// outputBuffer.get() returns the original value of |ptr| if it was already
+// aligned on an 8=byte boundary. Otherwise, it returns the size of an heap
+// allocated zeroed buffer of |size| bytes.
+//
+// outputBuffer.flush() copies the content of the heap allocated buffer back
+// to |ptr| explictly, if needed. If a no-op if |ptr| was aligned.
+class OutputBuffer {
+public:
+    OutputBuffer(unsigned char* ptr, size_t size, size_t align = 8) :
+            mOrgBuff(ptr), mBuff(ptr), mSize(size) {
+        if (((uintptr_t)ptr & (align - 1U)) != 0) {
+            void* newBuff = calloc(1, size);
+            mBuff = newBuff;
+        }
+    }
+
+    ~OutputBuffer() {
+        if (mBuff != mOrgBuff) {
+            free(mBuff);
+        }
+    }
+
+    void* get() const {
+        return mBuff;
+    }
+
+    void flush() {
+        if (mBuff != mOrgBuff) {
+            memcpy(mOrgBuff, mBuff, mSize);
+        }
+    }
+private:
+    unsigned char* mOrgBuff;
+    void* mBuff;
+    size_t mSize;
+};
+
+}  // namespace emugl
+
+#endif  // EMUGL_PROTOCOL_UTILS_H