Patent ID: 7437657

Claim:
A method of performing add-compare-selection, the method comprising: providing first and second path metrics in carry-save format having respective sum and carry components; producing first and second competing path metrics in carry-save format having sum and carry components in response to the first and second branch metrics; presenting the sum and carry components of the first competing path metric and the inverse of the sum and carry components of the second competing path metric to determine a first difference having sum and carry components; presenting the inverse of the sum and carry components of the first competing path metric and the sum and carry components of the second competing path metric to determine a second difference having sum and carry components; adding respective sum and carry components of the first and second differences to produce respective first and second resolved differences; presenting the carry and save components of the first competing path metric and a normalization factor to produce a normalized sum and a normalized carry for the first competing path metric; presenting the carry and save components of the second competing path metric and the normalization factor to produce a normalized sum and a normalized carry for the second competing path metric; selecting the normalized sum and normalized carry corresponding to one of the competing path metrics; providing one of the first and second differences, as determined by the sign of the first resolved difference, as an absolute value to produce a corrective factor; and presenting the selected normalized sum, selected normalized carry and said corrective factor to produce sum and carry components of a new path metric.