typedef struct alloc_device_t {
    struct hw_device_t common;

    /*
     * (*alloc)() Allocates a buffer in graphic memory with the requested
     * parameters and returns a buffer_handle_t and the stride in pixels to
     * allow the implementation to satisfy hardware constraints on the width
     * of a pixmap (eg: it may have to be multiple of 8 pixels).
     * The CALLER TAKES OWNERSHIP of the buffer_handle_t.
     *
     * Returns 0 on success or -errno on error.
     */

    int (*alloc)(struct alloc_device_t* dev,
            int w, int h, int format, int usage,
            buffer_handle_t* handle, int* stride,
	    unsigned int* text, ogl_alloc_t ogl_alloc,
	    ogl_free_t ogl_free);

    /*
     * (*free)() Frees a previously allocated buffer.
     * Behavior is undefined if the buffer is still mapped in any process,
     * but shall not result in termination of the program or security breaches
     * (allowing a process to get access to another process' buffers).
     * THIS FUNCTION TAKES OWNERSHIP of the buffer_handle_t which becomes
     * invalid after the call.
     *
     * Returns 0 on success or -errno on error.
     */
    int (*free)(struct alloc_device_t* dev,
            buffer_handle_t handle);


    void (*flush)(struct alloc_device_t* dev);

} alloc_device_t;