Mip map/rip map texture linear addressing memory organization and address generator

An apparatus for calculating a linear memory address of a texture data having 2-D virtual address coordinates (u,v) in a particular level (du,dv) of subsampling of a rip map, wherein said rip map includes (ML+1).sup.2 levels of texture data, with different combinations of first and second levels of subsampling (du,dv) in directions of said coordinates u and v, respectively, (0,0), (0,1), . . . , (0,ML), (1,0), (1,1), . . . , (1,ML), (ML,ML), comprising:

• a first adder stage for adding v to a first global offset GOV to produce a first sum, and for adding u to a second global offset GOU to produce a second sum,
• a concatenator circuit, for concatenating said first and second sums to produce a concatenated sum, said first sum forming a most significant fragment of said concatenated sum and said second sum forming a least significant fragment of said concatenated sum, and
• a second adder stage for adding said concatenated sum to a base address Base to produce said linear address,
• wherein said data arrays are divided into groups such that each data array of each one of said groups is subsampled at the same first level of subsampling, wherein each group has at least one span, including one span for each different coordinate value, in a first direction, of a domain of said texture data in said group, wherein each span comprises one subsequence of texture data from each data array in said group, arranged in order of increasing second level of subsampling, wherein each of said one subsequences of texture data comprises texture data from a corresponding array, with the same coordinate value in a second direction as said span, said texture data being arranged in said one subsequence of texture data in order of coordinate in said second direction, wherein each of plural continuous subsequences of a continuous subsequence of linear addresses is assigned to said spans in order of increasing second level of subsampling and order of increasing coordinate value in said second direction, such that a first level and a next level of subsampling being retrievable utilizing the same base address.

A method for storing texture data in a memory comprising:

• organizing said texture data into plural arrays of data, including a first data array, containing plural texture data values at a maximum resolution, and other data arrays, each containing a different level of subsampling of said data values of said first data array for a first portion of data arrays and a second portion of data arrays, and
• storing said texture data of said plural arrays of data in continuous, subsequences of a continuous sequence of linear memory addresses, said subsequences being assigned to said texture data of said plural arrays of data in order of level of subsampling,
• wherein said first portion of data arrays form a mip map with ML+1 data arrays, where ML is an integer .gtoreq.1, wherein each of said first portion of data arrays is subsampled with a first level of subsampling in each direction of said array, and wherein each of said subsequences of linear addresses is assigned to a respective one of said first portion of data arrays in order of increasing level of subsampling,
• wherein said second portion of data arrays form a rip map with (ML+1).sup.2 data arrays, where ML is an integer .gtoreq.1, each of said second portion of data arrays being subsampled at a different combination of second and third levels of subsamplings in first and second directions of said arrays, respectively, wherein said second portion of data arrays are divided into groups such that each data array of each one of said groups is subsampled at the same second level of subsampling, in said first direction,
• wherein each group has at least one span, including one span for each different coordinate value, in said first direction, of a domain of texture data in said group, wherein each span comprises one subsequence of texture data from each data array in said group, arranged in order of increasing third level of subsampling, wherein each of said one subsequences of texture data comprises texture data from a corresponding array, with the same coordinate in said first direction as said span, said texture data being arranged in said one subsequence in order of coordinate value in said second direction,
• wherein each of said subsequences is assigned to said at least one span in order of increasing third level of subsampling and order of increasing coordinate in said second direction.