The specific lattice filter implementations considered here are the short-term analysis and synthesis filter realizations in the GSM Full Rate (06.10) specifications. With the ETSI math operations like multiply with round (mult_r) to be performed, and with TMS320C62xx’s instruction set not consisting of any mult_r or even round operation, the C compiler generated code fails to achieve the best performance. With techniques like unrolling the loop, intelligent scheduling of the math operations in the pipeline and so on, and hand coding in assembly, we show how to achieve a performance better than that of a processor with operations like mult_r in its instruction set.