From: Gerhard Sittig Date: Sat, 20 Mar 2021 14:43:13 +0000 (+0100) Subject: ieee488: add support for parallel poll (PP) X-Git-Url: http://sigrok.org/gitweb/?a=commitdiff_plain;h=c70c28c896ad0509a7fe1b2129c60259c202cb98;hp=bcb8698eb151b51c17f9205e8752c3ee1413535a;p=libsigrokdecode.git ieee488: add support for parallel poll (PP) The concurrent assertion of ATN and EOI is a PP (parallel poll) query. The host asserts the control signals, and configured devices may assert the DIO lines in response. Because DAV is not involved, and because the input capture may not have DIO at the start of the PP phase, and may neither have DIO any more at its end, the check for parallel poll is more complex. Unconditionally inspecting each sample of the capture is inefficient. Keep manipulating the main loop's wait conditions instead, to stick with edge navigation as long as possible, and only switch to inspection of individual samples when strictly needed. It's also important to gracefully handle low oversampling. Existing test cases suffered from PP glitches when ATN asserted in the same location where EOI deasserted. Be extra conservative about the presence of the PP phase, expect at least two samples (a difference between its start and end position) before emitting the annotation. --- diff --git a/decoders/ieee488/pd.py b/decoders/ieee488/pd.py index 7d91a07..b0948a6 100644 --- a/decoders/ieee488/pd.py +++ b/decoders/ieee488/pd.py @@ -69,6 +69,8 @@ GPIB level byte fields (commands, addresses, pieces of data): when addressing channels within the device. - 'DATA_BYTE': is the talker address (when available), is the raw data byte (transport layer, ATN inactive). + - 'PPOLL': is not applicable, is a list of bit indices + (DIO1 to DIO8 order) which responded to the PP request. Extracted payload information (peers and their communicated data): - 'TALK_LISTEN': is the current talker, is the list of @@ -239,11 +241,12 @@ PIN_DATA = PIN_DIO1 ANN_RAW_BIT, ANN_RAW_BYTE, ANN_CMD, ANN_LADDR, ANN_TADDR, ANN_SADDR, ANN_DATA, ANN_EOI, + ANN_PP, ANN_TEXT, # TODO Want to provide one annotation class per talker address (0-30)? ANN_IEC_PERIPH, ANN_WARN, -) = range(11) +) = range(12) ( BIN_RAW, @@ -300,6 +303,7 @@ class Decoder(srd.Decoder): ('saddr', 'Secondary address'), ('data', 'Data byte'), ('eoi', 'EOI'), + ('pp', 'Parallel poll'), ('text', 'Talker text'), ('periph', 'IEC bus peripherals'), ('warning', 'Warning'), @@ -309,6 +313,7 @@ class Decoder(srd.Decoder): ('raws', 'Raw bytes', (ANN_RAW_BYTE,)), ('gpib', 'Commands/data', (ANN_CMD, ANN_LADDR, ANN_TADDR, ANN_SADDR, ANN_DATA,)), ('eois', 'EOI', (ANN_EOI,)), + ('polls', 'Polls', (ANN_PP,)), ('texts', 'Talker texts', (ANN_TEXT,)), ('periphs', 'IEC peripherals', (ANN_IEC_PERIPH,)), ('warnings', 'Warnings', (ANN_WARN,)), @@ -335,6 +340,7 @@ class Decoder(srd.Decoder): self.es_eoi = None self.ss_text = None self.es_text = None + self.ss_pp = None self.last_talker = None self.last_listener = [] self.last_iec_addr = None @@ -403,6 +409,63 @@ class Decoder(srd.Decoder): if had_eol and not is_eol: self.flush_bytes_text_accu() + def check_pp(self, dio = None): + # The combination of ATN and EOI means PP (parallel poll). Track + # this condition's start and end, and keep grabing the DIO lines' + # state as long as the condition is seen, since DAV is not used + # in the PP communication. + capture_in_pp = self.curr_atn and self.curr_eoi + decoder_in_pp = self.ss_pp is not None + if capture_in_pp and not decoder_in_pp: + # Phase starts. Track its ss. Start collecting DIO state. + self.ss_pp = self.samplenum + self.dio_pp = [] + return 'enter' + if not capture_in_pp and decoder_in_pp: + # Phase ends. Void its ss. Process collected DIO state. + ss, es = self.ss_pp, self.samplenum + dio = self.dio_pp or [] + self.ss_pp, self.dio_pp = None, None + if ss == es: + # False positive, caused by low oversampling. + return 'leave' + # Emit its annotation. Translate bit indices 0..7 for the + # DIO1..DIO8 signals to display text. Pass bit indices in + # the Python output for upper layers. + # + # TODO The presentation of this information may need more + # adjustment. The bit positions need not translate to known + # device addresses. Bits need not even belong to a single + # device. Participants and their location in the DIO pattern + # is configurable. Leave the interpretation to upper layers. + bits = [i for i, b in enumerate(dio) if b] + bits_text = ' '.join(['{}'.format(i + 1) for i in bits]) + dios = ['DIO{}'.format(i + 1) for i in bits] + dios_text = ' '.join(dios or ['-']) + text = [ + 'PPOLL {}'.format(dios_text), + 'PP {}'.format(bits_text), + 'PP', + ] + self.emit_data_ann(ss, es, ANN_PP, text) + self.putpy(ss, es, 'PPOLL', None, bits) + # Cease collecting DIO state. + return 'leave' + if decoder_in_pp: + # Keep collecting DIO state for each individual sample in + # the PP phase. Logically OR all DIO values that were seen. + # This increases robustness for low oversampling captures, + # where DIO may no longer be asserted when ATN/EOI deassert, + # and DIO was not asserted yet when ATN/EOI start asserting. + if dio is None: + dio = [] + if len(dio) > len(self.dio_pp): + self.dio_pp.extend([ 0, ] * (len(dio) - len(self.dio_pp))) + for i, b in enumerate(dio): + self.dio_pp[i] |= b + return 'keep' + return 'idle' + def handle_ifc_change(self, ifc): # Track IFC line for parallel input. # Assertion of IFC de-selects all talkers and listeners. @@ -692,6 +755,11 @@ class Decoder(srd.Decoder): # low signal levels, i.e. won't include the initial falling edge. # Scan for ATN/EOI edges as well (including the trick which works # around initial pin state). + # + # Use efficient edge based wait conditions for most activities, + # though some phases may require individual inspection of each + # sample (think parallel poll in combination with slow sampling). + # # Map low-active physical transport lines to positive logic here, # to simplify logical inspection/decoding of communicated data, # and to avoid redundancy and inconsistency in later code paths. @@ -708,6 +776,14 @@ class Decoder(srd.Decoder): if has_ifc: idx_ifc = len(waitcond) waitcond.append({PIN_IFC: 'l'}) + idx_pp_check = None + def add_data_cond(conds): + idx = len(conds) + conds.append({'skip': 1}) + return idx + def del_data_cond(conds, idx): + conds.pop(idx) + return None while True: pins = self.wait(waitcond) pins = self.invert_pins(pins) @@ -716,18 +792,34 @@ class Decoder(srd.Decoder): # captures, many edges fall onto the same sample number. So # we process active edges of flags early (before processing # data bits), and inactive edges late (after data got processed). + want_pp_check = False if idx_ifc is not None and self.matched[idx_ifc] and pins[PIN_IFC] == 1: self.handle_ifc_change(pins[PIN_IFC]) if idx_eoi is not None and self.matched[idx_eoi] and pins[PIN_EOI] == 1: self.handle_eoi_change(pins[PIN_EOI]) + want_pp_check = True if self.matched[idx_atn] and pins[PIN_ATN] == 1: self.handle_atn_change(pins[PIN_ATN]) + want_pp_check = True + if want_pp_check and not idx_pp_check: + pp = self.check_pp() + if pp in ('enter',): + idx_pp_check = add_data_cond(waitcond) if self.matched[idx_dav]: self.handle_dav_change(pins[PIN_DAV], pins[PIN_DIO1:PIN_DIO8 + 1]) + if idx_pp_check: + pp = self.check_pp(pins[PIN_DIO1:PIN_DIO8 + 1]) + want_pp_check = False if self.matched[idx_atn] and pins[PIN_ATN] == 0: self.handle_atn_change(pins[PIN_ATN]) + want_pp_check = True if idx_eoi is not None and self.matched[idx_eoi] and pins[PIN_EOI] == 0: self.handle_eoi_change(pins[PIN_EOI]) + want_pp_check = True + if idx_pp_check is not None and want_pp_check: + pp = self.check_pp(pins[PIN_DIO1:PIN_DIO8 + 1]) + if pp in ('leave',) and idx_pp_check is not None: + idx_pp_check = del_data_cond(waitcond, idx_pp_check) if idx_ifc is not None and self.matched[idx_ifc] and pins[PIN_IFC] == 0: self.handle_ifc_change(pins[PIN_IFC])