+ def handle_idle(self, sym):
+ self.samplenum_edge = self.samplenum
+ se0_length = float(self.samplenum - self.samplenum_lastedge) / self.samplerate
+ if se0_length > 2.5e-6: # 2.5us
+ self.putpb(['RESET', None])
+ self.putb([10, ['Reset', 'Res', 'R']])
+ self.signalling = self.options['signalling']
+ elif se0_length > 1.2e-6 and self.signalling == 'low-speed':
+ self.putpb(['KEEP ALIVE', None])
+ self.putb([9, ['Keep-alive', 'KA', 'A']])
+
+ if sym == 'FS_J':
+ self.signalling = 'full-speed'
+ self.update_bitrate()
+ elif sym == 'LS_J':
+ self.signalling = 'low-speed'
+ self.update_bitrate()
+ self.oldsym = 'J'
+ self.state = 'IDLE'
+
+ def decode(self):
+ if not self.samplerate:
+ raise SamplerateError('Cannot decode without samplerate.')
+
+ # Seed internal state from the very first sample.
+ pins = self.wait({'skip': 1})
+ sym = symbols[self.options['signalling']][pins]
+ self.handle_idle(sym)
+
+ while True:
+ # State machine.
+ if self.state == 'IDLE':
+ # Wait for any edge on either DP and/or DM.
+ pins = self.wait([{0: 'e'}, {1: 'e'}])
+ sym = symbols[self.signalling][pins]
+ if sym == 'SE0':
+ self.samplenum_lastedge = self.samplenum
+ self.state = 'WAIT IDLE'
+ else:
+ self.wait_for_sop(sym)
+ self.edgepins = pins
+ elif self.state in ('GET BIT', 'GET EOP'):
+ # Wait until we're in the middle of the desired bit.
+ self.edgepins = self.wait([{'skip': self.samplenum_edge - self.samplenum}])
+ pins = self.wait([{'skip': self.samplenum_target - self.samplenum}])
+
+ sym = symbols[self.signalling][pins]
+ if self.state == 'GET BIT':
+ self.get_bit(sym)
+ elif self.state == 'GET EOP':
+ self.get_eop(sym)
+ elif self.state == 'WAIT IDLE':
+ # Skip "all-low" input. Wait for high level on either DP or DM.
+ pins = self.wait({'skip': 1})
+ while not pins[0] and not pins[1]:
+ pins = self.wait([{0: 'h'}, {1: 'h'}])
+ if self.samplenum - self.samplenum_lastedge > 1:
+ sym = symbols[self.options['signalling']][pins]
+ self.handle_idle(sym)
+ else:
+ sym = symbols[self.signalling][pins]
+ self.wait_for_sop(sym)
+ self.edgepins = pins