- if (old_owr == 0 and owr == 1):
- # Data bit cycle length should be between 2*T and
- if (self.samplenum < self.lnk_start + 2*self.time_base):
- if (self.lnk_cnt == 8)
- self.put(self.startsample, self.samplenum - 1, self.out_proto, ['BYTE', self.lnk_byte])
- self.lnk_cnt = 0
- if (self.samplenum == self.lnk_start + 8*self.time_base):
- self.put(self.startsample, self.samplenum - 1, self.out_proto, ['RESET'])
-
- # Go to waiting for sample time
- self.lnk_state = 'WAIT FOR SAMPLE'
+ if (owr == 1):
+ # A reset cycle is longer than 8T
+ if (self.samplenum - self.lnk_fall > 8*self.time_base):
+ # Save the sample number for the falling edge.
+ self.lnk_rise = self.samplenum
+ # Send a reset event to the next protocol layer
+ self.lnk_event = "RESET"
+ self.lnk_state = "WAIT FOR PRESENCE DETECT"
+ elif self.lnk_state == 'WAIT FOR PRESENCE DETECT':
+ # Data should be sample one 'time unit' after a falling edge
+ if (self.samplenum - self.lnk_rise == 2.5*self.time_base):
+ self.lnk_bit = owr & 0x1
+ self.lnk_event = "PRESENCE DETECT"
+ if (self.lnk_bit) : self.lnk_state = 'WAIT FOR FALLING EDGE'
+ else : self.lnk_state = 'WAIT FOR RISING EDGE'
+ else:
+ raise Exception('Invalid lnk_state: %d' % self.lnk_state)
+
+ # Network layer
+
+ # Clear events.
+ self.net_event = "RESET"
+ # State machine.
+ if self.lnk_event == "RESET":
+ self.net_state = "WAIT FOR COMMAND"
+ self.net_cnt = 0
+ self.net_cmd = 0
+ elif self.lnk_event == "DATA BIT"
+ if self.net_state == "WAIT FOR COMMAND"
+ self.net_cnt = self.net_cnt + 1
+ self.net_cmd = (self.net_cmd << 1) & self.lnk_bit
+ if (self.lnk_cnt == 8)
+ self.put(self.startsample, self.samplenum - 1, self.out_proto, ['BYTE', self.lnk_byte])
+ if self.net_cmd == 0x33:
+ # READ ROM
+ elif self.net_cmd == 0x0f
+ # READ ROM
+ elif self.net_cmd == 0xcc
+ # SKIP ROM
+ elif self.net_cmd == 0x55
+ # MATCH ROM
+ elif self.net_cmd == 0xf0
+ # SEARCH ROM
+ elif self.net_cmd == 0x3c
+ # OVERDRIVE SKIP ROM
+ elif self.net_cmd == 0x69
+ # OVERDRIVE MATCH ROM
+ self.lnk_cnt = 0
+ if self.net_state == "WAIT FOR ROM":
+ #
+ else:
+ raise Exception('Invalid net_state: %d' % self.net_state)
+ elif not (self.lnk_event == "NONE"):
+ raise Exception('Invalid net_event: %d' % self.net_event)