A method and apparatus for performing add-compare-select processing using carry-save arithmetic. Data compressors that operate based upon carry-save principles are utilized to render the correct result without requiring intermediate results to be resolved. Intermediate results are truncated to ensure that the dynamic range of the add-compare-select unit is not exceeded, whilst ensuring that the resolution of the intermediate results is not adversely affected. The computation of two competing paths is delayed and only the difference is computed directly, resulting in a reduction of the propagation path through the add-compare-select unit.