Patent ID: 8106921

Claim:
A method of operating a microprocessor in a microprocessor system comprising a 3D graphics processor and a microprocessor that can control 3D graphics processor, the method comprising the steps of: selecting sets of data values for comparison; storing one of the selected sets of data values as fragment data for a plurality of positions in a graphics fragments array in a memory unit or accessible to the 3D graphics rendering module; storing the other selected set or sets of data values as texture map values in memory unit accessible to a texture mapping unit of the 3D graphics rendering module; rendering a 3D graphics primitive such that the fragments of the primitive have the same fragment positions as the stored data values in the memory unit and acquire desired data values from the stored texture map values as the are rendered; comparing the rendered primitive fragment data values with the data values for the corresponding fragment positions stored in the unit of or accessible to the 3D graphics rendering module and determining the differences between the data values being compared for each fragment position; and accumulating the determined differences for said data values for said plurality of fragment positions and providing an overall accumulated difference value for said plurality of fragment positions for said sets of data values being compared.