A non-transitory machine-readable medium, having encoded thereon program code, wherein, when the program code is executed by a machine, the machine implements a computer-aided design method, the computer-aided design method comprising:
- (A) simulating performance of a read channel having a sequence detector and a turbo-decoder configured to use a first parity-check matrix, wherein a first set of log-likelihood-ratio values is generated by simulating an output of the sequence detector;
- and
- (B) simulating performance of said read channel with the turbo-decoder being configured to use a second parity-check matrix different from the first parity-check matrix, wherein the first set of log-likelihood-ratio values is used to simulate performance of the turbo-decoder configured to use the second parity-check matrix.