+ self.putpb(['ERR', None])
+ self.putb([8, ['Bit stuff error', 'BS ERR', 'B']])
+ self.state = 'IDLE'
+ else:
+ # Normal bit (not a stuff bit).
+ self.putpb(['BIT', b])
+ self.putb([6, ['%s' % b]])
+ if b == '1':
+ self.consecutive_ones += 1
+ else:
+ self.consecutive_ones = 0
+
+ def get_eop(self, sym):
+ # EOP: SE0 for >= 1 bittime (usually 2 bittimes), then J.
+ self.set_new_target_samplenum()
+ self.putpb(['SYM', sym])
+ self.putb(sym_annotation[sym])
+ self.oldsym = sym
+ if sym == 'SE0':
+ pass
+ elif sym == 'J':
+ # Got an EOP.
+ self.putpm(['EOP', None])
+ self.putm([5, ['EOP', 'E']])
+ self.state = 'WAIT IDLE'
+ else:
+ self.putpm(['ERR', None])
+ self.putm([8, ['EOP Error', 'EErr', 'E']])
+ self.state = 'IDLE'
+
+ def get_bit(self, sym):
+ self.set_new_target_samplenum()
+ b = '0' if self.oldsym != sym else '1'
+ self.oldsym = sym
+ if sym == 'SE0':
+ # Start of an EOP. Change state, save edge
+ self.state = 'GET EOP'
+ self.ss_block = self.samplenum_lastedge
+ else:
+ self.handle_bit(b)
+ self.putpb(['SYM', sym])
+ self.putb(sym_annotation[sym])
+ if len(self.bits) <= 16:
+ self.bits += b
+ if len(self.bits) == 16 and self.bits == '0000000100111100':
+ # Sync and low-speed PREamble seen
+ self.putpx(['EOP', None])
+ self.state = 'IDLE'
+ self.signalling = 'low-speed-rp'
+ self.update_bitrate()
+ self.oldsym = 'J'
+ if b == '0':
+ edgesym = symbols[self.signalling][tuple(self.edgepins)]
+ if edgesym not in ('SE0', 'SE1'):
+ if edgesym == sym:
+ self.bitwidth = self.bitwidth - (0.001 * self.bitwidth)
+ self.samplepos = self.samplepos - (0.01 * self.bitwidth)
+ else:
+ self.bitwidth = self.bitwidth + (0.001 * self.bitwidth)
+ self.samplepos = self.samplepos + (0.01 * self.bitwidth)
+
+ 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()
+ 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'