Method and apparatus for performing setup operations in a video graphics system

A method for parameter calculation for primitives in a video graphics display system, the method comprising:

• receiving a stream of primitives, wherein each primitive of the stream of primitives includes a plurality of parameters that describe the primitive;
• determining if a first parameter of the plurality of parameters exceeds a threshold value;
• when the first parameter exceeds the threshold value, calculating parameter values for at least the first parameter of the primitive using a first setup engine;
• when the first parameter does not exceed the threshold value, calculating the parameter values for at least the first parameter of the primitive using a second setup engine;
• combining results of the first setup engine and the second setup engine to produce a resultant stream, wherein the resultant stream includes the parameter values for each parameter of each primitive of the stream of primitives.

An apparatus for preparing graphics primitives for rasterization, the apparatus comprising:

• a fast setup block that includes at least one reduced-size arithmetic unit, wherein the at least one reduced-size arithmetic unit calculates parameter values for graphics primitives;
• a full-size setup block that includes a full-size arithmetic unit, wherein the full-size arithmetic unit calculates parameter values for graphics primitives, and wherein the full-size arithmetic unit can perform more complex calculations than the at least one reduced-arithmetic unit of the fast setup block;
• a range determiner operably coupled to the fast setup block and the full-size setup block, wherein the range determiner receives a stream of graphics primitives and determines a range of at least one parameter of each graphics primitive of the stream of graphics primitives, wherein, based on the range, the range determiner allocates calculation of parameter values for each graphics primitive to one of the fast setup block and the full-size setup block;
• and
• a combining block operably coupled to the fast setup block and the full-size setup block, wherein the combining block combines output of the fast setup block with output of the full-size setup block to produce a resultant stream.

An apparatus for preparing triangle primitives for rasterization, comprising:

• a first setup block that receives triangles and calculates parameter values for the triangles using a first arithmetic unit;
• a second setup block that receives triangles and calculates parameter values for the triangles using a second arithmetic unit, wherein the second arithmetic unit is larger than the first arithmetic unit;
• an area block operably coupled to the first and second setup blocks, wherein the area block receives a stream of triangle primitives and determines if the area of each triangle primitive of the stream of triangle primitives exceeds an area threshold, wherein when a triangle primitive exceeds the area threshold, the triangle is passed to the second setup block, and wherein when the triangle primitive does not exceed the area threshold, the triangle is passed to the first setup block;
• and
• a combining block operably coupled to the first and second setup blocks, wherein the combining block combines output from the first and second setup blocks.