Viterbi decoding is performed on a microcontroller by initializing a state-metric array by executing load instructions to load state-metric data from a memory module into a set of registers in the microcontroller. Butterfly processing on the state-metric array is performed by executing Viterbi processing instructions fetched from a program storage module to manipulate the state-metric (SM) data in the set of registers for each Viterbi butterfly in a stage of Viterbi decoding to form a final set of state-metric data and trace bits. After completing each stage, a final set of state-metric data is stored in the memory module by executing store instructions.