Abstract: Techniques relating to providing clock signals to a storage element. Generally, different portions of a given storage element may be clocked according to different schemes. This technique may be pertinent to a storage element that has a portion for which the associated bit values do not change frequently relative to another portion of the storage element. For such a storage element, a high-frequency portion may be clocked upon an access to the storage element, while a low-frequency portion may be clocked only if there is a change in the associated bit values. This technique can be applied to various storage elements, including registers and FIFO buffer entries. An apparatus may be designed such that the low-frequency and high-frequency portions of a storage element do not change during operation. Alternatively, the low-frequency and high-frequency portions of the storage element may be changeable based on a current operating mode of the apparatus.

Abstract: Techniques relating to providing clock signals to a storage element. Generally, different portions of a given storage element may be clocked according to different schemes. This technique may be pertinent to a storage element that has a portion for which the associated bit values do not change frequently relative to another portion of the storage element. For such a storage element, a high-frequency portion may be clocked upon an access to the storage element, while a low-frequency portion may be clocked only if there is a change in the associated bit values. This technique can be applied to various storage elements, including registers and FIFO buffer entries. An apparatus may be designed such that the low-frequency and high-frequency portions of a storage element do not change during operation. Alternatively, the low-frequency and high-frequency portions of the storage element may be changeable based on a current operating mode of the apparatus.

Abstract: Techniques are disclosed relating to interpolation for texture mapping. In some embodiments, a graphics unit includes circuitry configured to map a texture to a screen space such that a set of multiple in the screen space falls between first and second adjacent texels of the texture in a first dimension. In some embodiments, the graphics unit also includes texture processing circuitry configured to perform different types of interpolation for pixels in the group of pixels. In these embodiments, this includes determining pixel attributes for first and second end groups of pixels in the set of pixels using a nearest-neighbor interpolation technique and attributes of the first and second texels respectively. In these embodiments, this also includes determining pixel attributes for an intermediate group of pixels in the set of pixels using a second, different interpolation technique and attributes of both the first and second texels.

Abstract: Techniques are disclosed relating to determining the location of a specified level of detail for a graphics texture. In some embodiments, an apparatus includes texture processing circuitry configured to receive information specifying a particular mipmap in a chain of stored mipmaps for a graphics texture and determine an offset address for the particular mipmap. In these embodiments, the texture processing circuitry is configured to determine the offset address by operating on a value that indicates a greatest potential chain size for chains of mipmaps in a graphics processing element. In these embodiments, the operating includes masking upper bits of the value based on a size of the texture and masking lower bits of the value based on a position of the specified mipmap in the chain of stored mipmaps. Disclosed techniques may reduce power consumption and/or area of circuitry configured to determine the offset.

Abstract: Techniques are disclosed relating to interpolation for texture mapping. In some embodiments, a graphics unit includes circuitry configured to map a texture to a screen space such that a set of multiple in the screen space falls between first and second adjacent texels of the texture in a first dimension. In some embodiments, the graphics unit also includes texture processing circuitry configured to perform different types of interpolation for pixels in the group of pixels. In these embodiments, this includes determining pixel attributes for first and second end groups of pixels in the set of pixels using a nearest-neighbor interpolation technique and attributes of the first and second texels respectively. In these embodiments, this also includes determining pixel attributes for an intermediate group of pixels in the set of pixels using a second, different interpolation technique and attributes of both the first and second texels.

Abstract: Apparatus and systems utilizing fixed point filtering to perform floating point texture filtering. A texture pipe unit consisting of a texture addressing unit, texture cache unit, and texture filter unit accepts texture requests for a specified pixel from a resource and returns formatted bilinear filtered results based on the specific pixel's corresponding four texels. The texture filtering unit consists of a pre-formatter module, interpolator module, accumulator module and a format module. The pre-formatter module accepts texel data in a floating point or fixed point format. However, if the data is in a floating point format the pre-formatter module converts the floating point data into a normalized fixed point data format whereby the interpolator module may perform its bilinear interpolator functions using standardized fixed point systems and apparatus without necessitating the use of floating point arithmetic units.

Abstract: A shader pipe texture filter utilizes a level one cache system as a primary method of storage but with the ability to have the level one cache system read and write to a level two cache system when necessary. The level one cache system communicates with the level two cache system via a wide channel memory bus. In addition, the level one cache system can be configured to support dual shader pipe texture filters while maintaining access to the level two cache system. A method utilizing a level one cache system as a primary method of storage with the ability to have the level one cache system read and write a level two cache system when necessary is also presented. In addition, level one cache systems can allocate a defined area of memory to be sharable amongst other resources.

Abstract: A shader pipe texture filter utilizes a level one cache system as a primary method of storage but with the ability to have the level one cache system read and write to a level two cache system when necessary. The level one cache system communicates with the level two cache system via a wide channel memory bus. In addition, the level one cache system can be configured to support dual shader pipe texture filters while maintaining access to the level two cache system. A method utilizing a level one cache system as a primary method of storage with the ability to have the level one cache system read and write a level two cache system when necessary is also presented. In addition, level one cache systems can allocate a defined area of memory to be sharable amongst other resources.

Abstract: Each row of a row based shader engine comprises a shader pipe array, a texture filter, and a level one texture cache system. The shader pipe array accepts texture requests for a specified pixel from a resource and performs associated rendering calculations, outputting texel data. The texture mapping unit receives texel data from a level one cache system and through formatting and bilinear filtering interpolations, generates a formatted bilinear result based on a specific pixel's corresponding four texels. Utilizing multiple rows of a row based shader engine within the shader engine allows for the parallel processing of multiple simultaneous resource requests. A method for texture filtering utilizing a row based shader engine is also presented.

Abstract: Apparatus and systems utilizing multiple shader engines where each shader engine comprises multiple rows of shader engine filters combined with level one and level two cache systems. Each unified shader engine filter comprises a shader pipe array, and a texture mapping unit with access to a level one cache system and a level two cache. The shader pipe array accepts texture requests for a specified pixel from a resource and performs associated rendering calculations, outputting texel data. The texture mapping unit retrieves texel data stored in a level one cache system, with the ability to read and write to and from a level two cache system, and through formatting and bilinear filtering interpolations generates a formatted bilinear result based on the specific pixel's neighboring texels. Utilizing multiple rows of shader engine filters within a shader engine allows for the parallel processing of multiple simultaneous resource requests.

Abstract: Apparatus and systems utilizing fixed point filtering to perform floating point texture filtering. A texture pipe unit consisting of a texture addressing unit, texture cache unit, and texture filter unit accepts texture requests for a specified pixel from a resource and returns formatted bilinear filtered results based on the specific pixel's corresponding four texels. The texture filtering unit consists of a pre-formatter module, interpolator module, accumulator module and a format module. The pre-formatter module accepts texel data in a floating point or fixed point format. However, if the data is in a floating point format the pre-formatter module converts the floating point data into a normalized fixed point data format whereby the interpolator module may perform its bilinear interpolator functions using standardized fixed point systems and apparatus without necessitating the use of floating point arithmetic units.

Abstract: A compact image element encoding format selectively allocates a bit field within the format to alternately encode either multi-bit alpha resolution or increased color resolution. This encoding technique may be advantageously used to allocate encoding bits to model semi-transparency while using those same bits for other purposes (e.g., higher color resolution) in instances where semi-transparency is not required (e.g., for opaque image elements). In one advantageous embodiment, the same encoding format can provide either RGB5 or RGB4A3, on an image-element-by-image-element basis. Applications include but are not limited to texture mapping in a 3D computer graphics system such as a home video game system or a personal computer.

Abstract: A compact image element encoding format selectively allocates a bit field within the format to alternately encode either multi-bit alpha resolution or increased color resolution. This encoding technique may be advantageously used to allocate encoding bits to model semi-transparency while using those same bits for other purposes (e.g., higher color resolution) in instances where semi-transparency is not required (e.g., for opaque image elements). In one advantageous embodiment, the same encoding format can provide either RGB5 or RGB4A3, on an image-element-by-image-element basis. Applications include but are not limited to texture mapping in a 3D computer graphics system such as a home video game system or a personal computer.

Abstract: A graphics system including a custom graphics and audio processor produces exciting 2D and 3D graphics and surround sound. The system includes a graphics and audio processor including a 3D graphics pipeline and an audio digital signal processor. The same texture mapping hardware used for color texturing provides resampled z texturing for sprites with depth or other applications. A z blender performs a z blending operation in screen space to blend surface z values with z texel values to provide per-pixel mapping of resampled z textures onto sampled 3D surface locations. Z texels can represent absolute depths or depth displacements relative to primitive surface depth. The z texel values may add to or replace primitive surface z values, and a constant bias may be added if desired. The resulting depth values are used for occlusion testing. Z textures can be generated by copying out portions of an embedded z buffer and providing the copied depth values to the texture mapping hardware.

Abstract: A compact image element encoding format selectively allocates a bit field within the format to alternately encode either multi-bit alpha resolution or increased color resolution. This encoding technique may be advantageously used to allocate encoding bits to model semi-transparency while using those same bits for other purposes (e.g., higher color resolution) in instances where semi-transparency is not required (e.g., for opaque image elements). In one advantageous embodiment, the same encoding format can provide either RGB5 or RGB4A3, on an image-element-by-image-element basis. Applications include but are not limited to texture mapping in a 3D computer graphics system such as a home video game system or a personal computer.

Abstract: A low cost high performance three dimensional (3D) graphics system is disclosed that can model a world in three dimensions and project the model onto a two dimensional viewing plane selected based on a changeable viewpoint. The viewpoint can be changed on an interactive, real time basis by operating user input controls such as game controllers. The system rapidly produces a corresponding changing image (which can include animated cartoon characters or other animation) on the screen of a color television set. The richly featured high performance low cost system is intended to give consumers the change to interact in real time right inside magnificent virtual 3D worlds to provide a high degree of image realism, excitement and flexibility. An optimum feature set/architecture (including a custom designed graphics/audio coprocessor) provides high quality fast moving 3D images and digital stereo sound for video game play and other graphics applications.

Abstract: A low cost high performance three dimensional (3D) graphics system is disclosed that can model a world in three dimensions and project the model onto a two dimensional viewing plane selected based on a changeable viewpoint. The viewpoint can be changed on an interactive, real time basis by operating user input controls such as game controllers. The system rapidly produces a corresponding changing image (which can include animated cartoon characters or other animation) on the screen of a color television set.

Abstract: A low cost high performance three dimensional (3D) graphics system is disclosed that can model a world in three dimensions and project the model onto a two dimensional viewing plane selected based on a changeable viewpoint. The viewpoint can be changed on an interactive, real time basis by operating user input controls such as game controllers. The system rapidly produces a corresponding changing image (which can include animated cartoon characters or other animation) on the screen of a color television set. The richly featured high performance low cost system is intended to give consumers the chance to interact in real time right inside magnificent virtual 3D worlds to provide a high degree of image realism, excitement and flexibility. An optimum feature set/architecture (including a custom designed graphics/audio coprocessor) provides high quality fast moving 3D images and digital stereo sound for video game play and other graphics applications.

Abstract: The invention provides a method of generating cache indexes that reduces the likelihood that adjacent addresses will map to the same cache regions. The hashing process is optimized to be sensitive to small changes in the input data so that similar sets of input data will preferably not result in the same or even similar output data. Memory accesses of the sort performed when rendering graphical images may involve numerous accesses to relatively similar memory locations Therefore, hashing of the index values that determine where the information from the memory locations will be stored while that information is in cache decreases the likelihood of similar memory locations being stored at the same cache location. Consequently, cache efficiency and performance is improved.

Abstract: The invention provides a method of operating a cache memory so that operation is optimized. Instead of fetching data immediately upon a cache miss, the present invention continues with subsequent cache accesses. Decoupled from cache access, cache misses are fetched to cache. During operation, for each request in a sequence of data requests, it is determined if the requested data can be found in cache memory. If the data is not found in the cache, the next request in the sequence is processed without first retrieving the data pending from the earlier request. A miss list is generated for each of the requests in the sequence of requests whose data is not found in the cache. The data that is associated with the requests in the miss list is obtained from DRAM and used to satisfy the requests. Some cache lines may have one or more pending hits to data associated with the cache line. Those requests are kept in a pending hits list and processed in order as required.