Advanced graphics port (AGP) display driver with restricted execute mode for transparently transferring textures to a local texture cache

A personal computer comprising:

• a central processing unit (CPU) for executing user programs and software drivers;
• a main memory, for storing portions of the user programs and software drivers read by the CPU and for storing data;
• an accelerated graphics port (AGP) portion of the main memory for storing textures used by a user program that generates 3D graphics;
• a system-logic chip set, coupled between the CPU and the main memory, for transferring data between the CPU and the main memory;
• a graphics accelerator, controlled by a software driver executing on the CPU, for rendering pixels for display to a user on a display, the graphics accelerator including:
• a 3D rendering engine for applying textures to pixels;
• a graphics memory for storing pixels for display;
• a texture cache within the graphics memory, for storing a copy of a texture from the AGP portion of the main memory;
• an AGP bus, coupled between the system-logic chip set and the graphics accelerator, for transferring graphics data and instructions to the graphics accelerator;
• and
• a 3D graphics driver, executed by the CPU, for controlling the graphics accelerator, the 3D graphics diver for managing the texture cache, the 3D graphics driver copying a texture from the AGP portion of the main memory through the system-logic chip set, over the AGP bus to the texture cache when a user program instructs the 3D graphics driver to render a texture in the AGP portion of the main memory,
• whereby the 3D graphics driver, transparently to the user program, transfers textures from the AGP portion of the main memory to the texture cache in the graphics memory when 3D rendering is requested.

A computer-program product comprising:

• a computer-usable medium having computer-readable program code means embodied therein for controlling a 3D graphics accelerator chip and managing a texture cache, the computer-readable program code means in the computer-program product comprising:
• set-render means, called by a high-level application when a texture in a main memory is ready for rendering by a 3D graphics engine, for setting rendering registers in the 3D graphics engine;
• wherein the 3D graphics engine is unable to read textures from the main memory, the 3D graphics engine only able to read textures from the texture cache;
• handle-texture means, called by the set-render means before the 3D graphics engine is enabled to render the texture, for loading the texture into the texture cache readable by the 3D graphics engine;
• texture-transfer means, called by the handle-texture means, for copying the texture from the main memory to the texture cache;
• and
• cache management means, called by the handle-texture means, for generating a free block in the texture cache, the cache management means returning a free address of the free block to the handle-texture means, the Texture-transfer means using the free address as a destination address when moving the texture from the main memory,
• whereby the high-level application calls the set-render means to copy the texture in the AGP portion of the main memory to the texture cache readable by the 3D graphics engine.