Patent ID: 6871208

Claim:
A device for partial calculation of a 2-D inverse discrete cosine transform (IDCT), on a set of input data values, based on a coefficient matrix essentially as follows [ v p v n ] = [ C e T 0 0 C o T ] · [ u e u o ] , where u e and u 0 are even and odd indexed values in the set of input data values C e T and C 0 T are coefficient sub-matrices, v p is a vector of sums of output data values, and v n is a vector of differences of output data values, the device comprising: one or more input lines; and one or more adder networks, coupled with the input lines, including logic to pre-add said input data values to generate operands and to calculate v p =[C e ] T ·U e and v n =[C o ] T ·u o from the operands; logic to combine values of vectors v p and v n to produce a vector v of output data values, coupled to the adder networks; wherein said adder networks include carry save adders interconnected to produce intermediate sums and carries and further connected to an additional adder to produce a sum; wherein the set of input data values consists of eight values, u 0 . . . u 7 and the vectors v p and v n are essentially as follows [ vp ] = [ vp0 vp1 vp2 vp3 ] = [ v0 + v7 v1 + v6 v2 + v5 v3 + v4 ] ⁢ [ vn ] = [ vn0 vn1 vn2 vn3 ] = [ v0 - v7 v1 - v6 v2 - v5 v3 - v4 ] wherein successive sets of input data values constitute an 8×8 matrix of values, further comprising logic for presenting successive sets of input data values one set at a time, coupled between the input lines and the adder networks.