void mem_copy_from(device_memory& mem, int y, int w, int h, int elem)
	{
		thread_scoped_lock lock(rpc_lock);

		size_t data_size = mem.memory_size();

		RPCSend snd(socket, &error_func, "mem_copy_from");

		snd.add(mem);
		snd.add(y);
		snd.add(w);
		snd.add(h);
		snd.add(elem);
		snd.write();

		RPCReceive rcv(socket, &error_func);
		rcv.read_buffer((void*)mem.data_pointer, data_size);
	}

	void mem_free(device_memory& mem)
	{
		mem.device_pointer = 0;

		stats.mem_free(mem.memory_size());
	}

	void mem_zero(device_memory& mem)
	{
		memset((void*)mem.device_pointer, 0, mem.memory_size());
	}

	void mem_alloc(device_memory& mem, MemoryType type)
	{
		mem.device_pointer = mem.data_pointer;

		stats.mem_alloc(mem.memory_size());
	}

	void mem_alloc(device_memory& mem, MemoryType /*type*/)
	{
		mem.device_pointer = mem.data_pointer;
		mem.device_size = mem.memory_size();
		stats.mem_alloc(mem.device_size);
	}

void Device::draw_pixels(device_memory& rgba, int y, int w, int h, int dx, int dy, int width, int height, bool transparent,
	const DeviceDrawParams &draw_params)
{
	assert(rgba.type == MEM_PIXELS);

	mem_copy_from(rgba, y, w, h, rgba.memory_elements_size(1));

	if(transparent) {
		glEnable(GL_BLEND);
		glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
	}

	glColor3f(1.0f, 1.0f, 1.0f);

	if(rgba.data_type == TYPE_HALF) {
		/* for multi devices, this assumes the inefficient method that we allocate
		 * all pixels on the device even though we only render to a subset */
		GLhalf *host_pointer = (GLhalf*)rgba.host_pointer;
		float vbuffer[16], *basep;
		float *vp = NULL;

		host_pointer += 4*y*w;

		/* draw half float texture, GLSL shader for display transform assumed to be bound */
		GLuint texid;
		glGenTextures(1, &texid);
		glBindTexture(GL_TEXTURE_2D, texid);
		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F_ARB, w, h, 0, GL_RGBA, GL_HALF_FLOAT, host_pointer);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

		glEnable(GL_TEXTURE_2D);

		if(draw_params.bind_display_space_shader_cb) {
			draw_params.bind_display_space_shader_cb();
		}

		if(GLEW_VERSION_1_5) {
			if(!vertex_buffer)
				glGenBuffers(1, &vertex_buffer);

			glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
			/* invalidate old contents - avoids stalling if buffer is still waiting in queue to be rendered */
			glBufferData(GL_ARRAY_BUFFER, 16 * sizeof(float), NULL, GL_STREAM_DRAW);

			vp = (float *)glMapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY);

			basep = NULL;
		}
		else {
			basep = vbuffer;
			vp = vbuffer;
		}

		if(vp) {
			/* texture coordinate - vertex pair */
			vp[0] = 0.0f;
			vp[1] = 0.0f;
			vp[2] = dx;
			vp[3] = dy;

			vp[4] = 1.0f;
			vp[5] = 0.0f;
			vp[6] = (float)width + dx;
			vp[7] = dy;

			vp[8] = 1.0f;
			vp[9] = 1.0f;
			vp[10] = (float)width + dx;
			vp[11] = (float)height + dy;

			vp[12] = 0.0f;
			vp[13] = 1.0f;
			vp[14] = dx;
			vp[15] = (float)height + dy;

			if(vertex_buffer)
				glUnmapBuffer(GL_ARRAY_BUFFER);
		}

		glTexCoordPointer(2, GL_FLOAT, 4 * sizeof(float), basep);
		glVertexPointer(2, GL_FLOAT, 4 * sizeof(float), ((char *)basep) + 2 * sizeof(float));

		glEnableClientState(GL_VERTEX_ARRAY);
		glEnableClientState(GL_TEXTURE_COORD_ARRAY);

		glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

		glDisableClientState(GL_TEXTURE_COORD_ARRAY);
		glDisableClientState(GL_VERTEX_ARRAY);

		if(vertex_buffer) {
			glBindBuffer(GL_ARRAY_BUFFER, 0);
		}

		if(draw_params.unbind_display_space_shader_cb) {
			draw_params.unbind_display_space_shader_cb();
		}

		glBindTexture(GL_TEXTURE_2D, 0);
//.........这里部分代码省略.........

 virtual device_ptr mem_alloc_sub_ptr(device_memory &mem, int offset, int /*size*/)
 {
   return (device_ptr)(((char *)mem.device_pointer) + mem.memory_elements_size(offset));
 }