Figure 5

State diagram of the finite state machine (FSM). The states of the moore-type FSM are in the rounded rectangles. The output at each state are defined by the following vector - (we = write enable for SRAM blocks, rm = reset 64×SCM matrix, ena_seq = enable sequences to be loaded, ena_sf = enable scores and flags to be loaded). To clear all scores and flags from the matrix, the FSM is set to the 'Reset' state. Next, the FSM remains in the 'Wait for Sequence Load' state until two sequences of length 8 or less have been loaded by the C program. Once this loading is completed, the C program will assert the done_load signal. At this point, the FSM releases the matrix's reset signal which causes the sequences, scores and flags to propagate through the matrix. After a set delay determined by the critical path of the circuit, the FSM asserts the done_sw signal, and enables the values just calculated to be written into the RAM. Theses scores and flags will be read from the RAM for the next block. The FSM then returns to the 'Wait for Sequence Load' state, and waits for the next length of sequences to come from the C program. This loop is repeated until the entire Smith-Waterman matrix has been calculated and the score of the optimal alignment has been determined. Finally, the results are printed to a command window on the computer. The FSM can be reset by writing to a status register, allowing the matrix to be used for another set of sequences.