Example of non-blocking coding style:

(Have seen blocking style on earlier slide.)

Example: Non-blocking (untimed) transactor for the four-phase handshake.

bool nb_putbyte_start(char d) { if (ack) return false; data = d; settle(); // A H/W delay for skew issues, // or a memory fence in S/W for // sequential consistency. req = 1; return true; } bool nb_putbyte_end(char d) { if (!ack) return false; req = 0; return true; }

bool nb_getbyte_start(char &r) { if (!req) return false; r = data; ack = 1; return true; } bool nb_getbyte_end() { if (req) return false; ack = 0; return true; }

Both routines should be repeatedly called by the client until returning true.