import sigrokdecode as srd
-# Low-/full-speed symbols (used as states of our state machine, too).
+# Low-/full-speed symbols.
# Note: Low-speed J and K are inverted compared to the full-speed J and K!
symbols = {
'low-speed': {
'signalling': ['Signalling', 'full-speed'],
}
annotations = [
- ['Text', 'Human-readable text']
+ ['Text', 'Human-readable text'],
]
def __init__(self):
- self.sym = 'J' # The "idle" state is J.
+ self.oldsym = 'J' # The "idle" state is J.
+ self.ss_sop = -1
self.samplenum = 0
- self.scount = 0
self.packet = ''
self.syms = []
self.bitrate = None
self.bitwidth = None
+ self.bitnum = 0
+ self.samplenum_target = None
self.oldpins = None
+ self.consecutive_ones = 0
+ self.state = 'IDLE'
def start(self, metadata):
self.out_proto = self.add(srd.OUTPUT_PROTO, 'usb_signalling')
def report(self):
pass
- def putp(self, data):
+ def putpx(self, data):
self.put(self.samplenum, self.samplenum, self.out_proto, data)
def putx(self, data):
self.put(self.samplenum, self.samplenum, self.out_ann, data)
+ def putpb(self, data):
+ s, halfbit = self.samplenum, int(self.bitwidth / 2)
+ self.put(s - halfbit, s + halfbit, self.out_proto, data)
+
+ def putb(self, data):
+ s, halfbit = self.samplenum, int(self.bitwidth / 2)
+ self.put(s - halfbit, s + halfbit, self.out_ann, data)
+
+ def set_new_target_samplenum(self):
+ bitpos = self.ss_sop + (self.bitwidth / 2)
+ bitpos += self.bitnum * self.bitwidth
+ self.samplenum_target = int(bitpos)
+
+ def wait_for_sop(self, sym):
+ # Wait for a Start of Packet (SOP), i.e. a J->K symbol change.
+ if sym != 'K':
+ self.oldsym = sym
+ return
+ self.ss_sop = self.samplenum
+ self.set_new_target_samplenum()
+ self.putpx(['SOP', None])
+ self.putx([0, ['SOP']])
+ self.state = 'GET BIT'
+
+ def handle_bit(self, sym, b):
+ if self.consecutive_ones == 6 and b == '0':
+ # Stuff bit. Don't add to the packet, reset self.consecutive_ones.
+ self.putb([0, ['SB: %s/%s' % (sym, b)]])
+ self.consecutive_ones = 0
+ else:
+ # Normal bit. Add it to the packet, update self.consecutive_ones.
+ self.putb([0, ['%s/%s' % (sym, b)]])
+ self.packet += 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.syms.append(sym)
+ self.putpb(['SYM', sym])
+ self.putb([0, ['%s' % sym]])
+ self.bitnum += 1
+ self.set_new_target_samplenum()
+ self.oldsym = sym
+ if self.syms[-2:] == ['SE0', 'J']:
+ # Got an EOP, i.e. we now have a full packet.
+ self.putpb(['PACKET', self.packet])
+ self.putb([0, ['PACKET: %s' % self.packet]])
+ self.bitnum, self.packet, self.syms, self.state = 0, '', [], 'IDLE'
+ self.consecutive_ones = 0
+
+ def get_bit(self, sym):
+ if sym == 'SE0':
+ # Start of an EOP. Change state, run get_eop() for this bit.
+ self.state = 'GET EOP'
+ self.get_eop(sym)
+ return
+ self.syms.append(sym)
+ self.putpb(['SYM', sym])
+ b = '0' if self.oldsym != sym else '1'
+ self.handle_bit(sym, b)
+ self.bitnum += 1
+ self.set_new_target_samplenum()
+ self.oldsym = sym
+
def decode(self, ss, es, data):
for (self.samplenum, pins) in data:
-
- # Note: self.samplenum is the absolute sample number, whereas
- # self.scount only counts the number of samples since the
- # last change in the D+/D- lines.
- self.scount += 1
-
- # Ignore identical samples early on (for performance reasons).
- if self.oldpins == pins:
- continue
- self.oldpins, (dp, dm) = pins, pins
-
- sym = symbols[self.options['signalling']][dp, dm]
-
- self.putx([0, [sym]])
- self.putp(['SYM', sym])
-
- # Wait for a symbol change (i.e., change in D+/D- lines).
- if sym == self.sym:
- continue
-
- ## # Debug code:
- ## self.syms.append(sym + ' ')
- ## if len(self.syms) == 16:
- ## self.putx([0, [''.join(self.syms)]])
- ## self.syms = []
- # continue
-
- # How many bits since the last transition?
- if self.packet != '' or self.sym != 'J':
- bitcount = int((self.scount - 1) / self.bitwidth)
+ # State machine.
+ if self.state == 'IDLE':
+ # Ignore identical samples early on (for performance reasons).
+ if self.oldpins == pins:
+ continue
+ self.oldpins = pins
+ sym = symbols[self.options['signalling']][tuple(pins)]
+ self.wait_for_sop(sym)
+ elif self.state in ('GET BIT', 'GET EOP'):
+ # Wait until we're in the middle of the desired bit.
+ if self.samplenum < self.samplenum_target:
+ continue
+ sym = symbols[self.options['signalling']][tuple(pins)]
+ if self.state == 'GET BIT':
+ self.get_bit(sym)
+ elif self.state == 'GET EOP':
+ self.get_eop(sym)
else:
- bitcount = 0
-
- if self.sym == 'SE0':
- if bitcount == 1:
- # End-Of-Packet (EOP)
- # self.putx([0, [packet_decode(self.packet), self.packet]])
- if self.packet != '': # FIXME?
- self.putx([0, ['PACKET: %s' % self.packet]])
- self.putp(['PACKET', self.packet])
- else:
- # Longer than EOP, assume reset.
- self.putx([0, ['RESET']])
- self.putp(['RESET', None])
- # self.putx([0, [self.packet]])
- self.scount = 0
- self.sym = sym
- self.packet = ''
- continue
-
- # Add bits to the packet string.
- self.packet += '1' * bitcount
-
- # Handle bit stuffing.
- if bitcount < 6 and sym != 'SE0':
- self.packet += '0'
- elif bitcount > 6:
- self.putx([0, ['BIT STUFF ERROR']])
- self.putp(['BIT STUFF ERROR', None])
-
- self.scount = 0
- self.sym = sym
+ raise Exception('Invalid state: %s' % self.state)
projects / libsigrokdecode.git / commitdiff