uart: Add [rx|tx]_packet_delimiter options.

This is a convenience feature that emits summary annotations ("packets")
that comprise all data values that were decoded until a specified delimiter
value is seen (as last data value of the "packet").

Example use-cases include ASCII data where it can be convenient to
"packetize" whenever a 10/0x0A value (newline) is seen, or some
protocols which have a fixed "marker" value (e.g. 0x55) as last
value in the "packet".

The annotations are affected by the selected 'format' option, i.e. the
user can get summaries in ASCII or hex or other formats.

This is just an (intentionally very simple) helper/convenience improvement
and is NOT meant to replace "proper" stacked decoders for UART-based protocols.

1 files changed, 38 insertions, 0 deletions

diff --git a/decoders/uart/pd.py b/decoders/uart/pd.py
index 389284e..0a0d307 100644
--- a/decoders/uart/pd.py
+++ b/decoders/uart/pd.py
@@ -112,6 +112,10 @@ class Decoder(srd.Decoder):
             'values': ('yes', 'no')},
         {'id': 'invert_tx', 'desc': 'Invert TX?', 'default': 'no',
             'values': ('yes', 'no')},
+        {'id': 'rx_packet_delimiter', 'desc': 'RX packet delimiter (decimal)',
+            'default': -1},
+        {'id': 'tx_packet_delimiter', 'desc': 'TX packet delimiter (decimal)',
+            'default': -1},
     )
     annotations = (
         ('rx-data', 'RX data'),
@@ -130,16 +134,20 @@ class Decoder(srd.Decoder):
         ('tx-data-bits', 'TX data bits'),
         ('rx-break', 'RX break'),
         ('tx-break', 'TX break'),
+        ('rx-packet', 'RX packet'),
+        ('tx-packet', 'TX packet'),
     )
     annotation_rows = (
         ('rx-data', 'RX', (0, 2, 4, 6, 8)),
         ('rx-data-bits', 'RX bits', (12,)),
         ('rx-warnings', 'RX warnings', (10,)),
         ('rx-break', 'RX break', (14,)),
+        ('rx-packets', 'RX packets', (16,)),
         ('tx-data', 'TX', (1, 3, 5, 7, 9)),
         ('tx-data-bits', 'TX bits', (13,)),
         ('tx-warnings', 'TX warnings', (11,)),
         ('tx-break', 'TX break', (15,)),
+        ('tx-packets', 'TX packets', (17,)),
     )
     binary = (
         ('rx', 'RX dump'),
@@ -152,6 +160,10 @@ class Decoder(srd.Decoder):
         s, halfbit = self.startsample[rxtx], self.bit_width / 2.0
         self.put(s - floor(halfbit), self.samplenum + ceil(halfbit), self.out_ann, data)
 
+    def putx_packet(self, rxtx, data):
+        s, halfbit = self.ss_packet[rxtx], self.bit_width / 2.0
+        self.put(s - floor(halfbit), self.samplenum + ceil(halfbit), self.out_ann, data)
+
     def putpx(self, rxtx, data):
         s, halfbit = self.startsample[rxtx], self.bit_width / 2.0
         self.put(s - floor(halfbit), self.samplenum + ceil(halfbit), self.out_python, data)
@@ -191,6 +203,8 @@ class Decoder(srd.Decoder):
         self.state = ['WAIT FOR START BIT', 'WAIT FOR START BIT']
         self.databits = [[], []]
         self.break_start = [None, None]
+        self.packet_cache = [[], []]
+        self.ss_packet, self.es_packet = [None, None], [None, None]
 
     def start(self):
         self.out_python = self.register(srd.OUTPUT_PYTHON)
@@ -246,6 +260,28 @@ class Decoder(srd.Decoder):
 
         self.state[rxtx] = 'GET DATA BITS'
 
+    def handle_packet(self, rxtx):
+        opt = ('rx' if (rxtx == RX) else 'tx') + '_packet_delimiter'
+        delim = self.options[opt]
+        if delim == -1:
+            return
+
+        # Cache data values until we see the delimiter.
+        if len(self.packet_cache[rxtx]) == 0:
+            self.ss_packet[rxtx] = self.startsample[rxtx]
+        self.packet_cache[rxtx].append(self.datavalue[rxtx])
+        if self.datavalue[rxtx] == delim:
+            self.es_packet[rxtx] = self.samplenum
+            s = ''
+            for b in self.packet_cache[rxtx]:
+                s += self.format_value(b)
+                if self.options['format'] != 'ascii':
+                    s += ' '
+            if self.options['format'] != 'ascii' and s[-1] == ' ':
+                s = s[:-1] # Drop trailing space.
+            self.putx_packet(rxtx, [16 + rxtx, [s]])
+            self.packet_cache[rxtx] = []
+
     def get_data_bits(self, rxtx, signal):
         # Save the sample number of the middle of the first data bit.
         if self.startsample[rxtx] == -1:
@@ -279,6 +315,8 @@ class Decoder(srd.Decoder):
         self.putbin(rxtx, [rxtx, bdata])
         self.putbin(rxtx, [2, bdata])
 
+        self.handle_packet(rxtx)
+
         self.databits[rxtx] = []
 
         # Advance to either reception of the parity bit, or reception of