X-Git-Url: https://sigrok.org/gitweb/?a=blobdiff_plain;f=decoders%2Fsle44xx%2Fpd.py;h=775ee3c8a8fb78c9d29aa826a683e480e5da1885;hb=e4f70391abbb153364a534d45a59026961ce1b1f;hp=02bea428b694eec7f992fd5ad70cfb2ce9a1d004;hpb=c328c18123c83e0f1e54181b9634bec76a2e3c43;p=libsigrokdecode.git

diff --git a/decoders/sle44xx/pd.py b/decoders/sle44xx/pd.py
index 02bea42..775ee3c 100644
--- a/decoders/sle44xx/pd.py
+++ b/decoders/sle44xx/pd.py
@@ -17,6 +17,7 @@
 ## along with this program; if not, see <http://www.gnu.org/licenses/>.
 ##
 
+from common.srdhelper import bitpack_lsb
 import sigrokdecode as srd
 
 class Pin:
@@ -81,10 +82,8 @@ class Decoder(srd.Decoder):
 
     def reset(self):
         self.ss = self.es = self.ss_byte = -1
-        self.bitcount = 0
-        self.databyte = 0
         self.bits = []
-        self.cmd = 'RESET'
+        self.cmd = None
 
     def metadata(self, key, value):
         if key == srd.SRD_CONF_SAMPLERATE:
@@ -105,57 +104,61 @@ class Decoder(srd.Decoder):
         self.cmd = 'RESET'
         cls, texts = lookup_proto_ann_txt(self.cmd, {})
         self.putx([cls, texts])
-        self.bitcount = self.databyte = 0
         self.bits = []
-        self.cmd = 'ATR' # Next data bytes will be ATR
+        # Next data bytes will be Answer To Reset.
+        self.cmd = 'ATR'
 
     def handle_command(self, pins):
         rst, clk, io = pins
         self.ss, self.es = self.samplenum, self.samplenum
+        # XXX Is the comment inverted?
         # If I/O is rising -> command START
         # if I/O is falling -> command STOP and response data incoming
-        self.cmd = 'CMD' if (io == 0) else 'DATA'
-        self.bitcount = self.databyte = 0
+        self.cmd = 'CMD' if io == 0 else 'DATA'
         self.bits = []
 
     # Gather 8 bits of data
     def handle_data(self, pins):
         rst, clk, io = pins
 
-        # Data is transmitted LSB-first.
-        self.databyte |= (io << self.bitcount)
-
-        # Remember the start of the first data/address bit.
-        if self.bitcount == 0:
+        # Remember the start of the first data/address bit. Collect
+        # bits in LSB first order. "Estimate" the bit's width at first,
+        # update end times as better data becomes available.
+        # TODO This estimation logic is imprecise and fragile. A single
+        # slightly stretched clock period throws off the following bit
+        # annotation. Better look for more reliable conditions. Available
+        # documentation suggests bit values are valid during high CLK.
+        if not self.bits:
             self.ss_byte = self.samplenum
-
-        # Store individual bits and their start/end samplenumbers.
-        # In the list, index 0 represents the LSB (SLE44xx transmits LSB-first).
-        self.bits.insert(0, [io, self.samplenum, self.samplenum])
-        if self.bitcount > 0:
-            self.bits[1][2] = self.samplenum
-        if self.bitcount == 7:
-            self.bitwidth = self.bits[1][2] - self.bits[2][2]
-            self.bits[0][2] += self.bitwidth
-
-        # Return if we haven't collected all 8 bits, yet.
-        if self.bitcount < 7:
-            self.bitcount += 1
+        bit_val = io
+        bit_ss = self.samplenum
+        bit_es = bit_ss # self.bitwidth is not known yet.
+        if self.bits:
+            self.bits[-1][2] = bit_ss
+        self.bits.append([bit_val, bit_ss, bit_es])
+        if len(self.bits) < 8:
             return
+        bitwidth = self.bits[-1][1] - self.bits[-2][1]
+        self.bits[-1][2] += bitwidth
 
-        self.ss, self.es = self.ss_byte, self.samplenum + self.bitwidth
+        # Get the data byte value, and byte's ss/es.
+        databyte = bitpack_lsb(self.bits, 0)
+        self.ss_byte = self.bits[0][1]
+        self.es_byte = self.bits[-1][2]
 
-        self.putb([Bin.SEND_DATA, bytes([self.databyte])])
+        self.ss, self.es = self.ss_byte, self.es_byte
+        self.putb([Bin.SEND_DATA, bytes([databyte])])
 
+        # TODO Present bit values earlier. As soon as their es is known.
         for bit_val, bit_ss, bit_es in self.bits:
             cls, texts = lookup_proto_ann_txt('BIT', {'bit': bit_val})
             self.put(bit_ss, bit_es, self.out_ann, [cls, texts])
 
-        cls, texts = lookup_proto_ann_txt(self.cmd, {'data': self.databyte})
-        self.putx([cls, texts])
+        cls, texts = lookup_proto_ann_txt(self.cmd, {'data': databyte})
+        if cls:
+            self.putx([cls, texts])
 
         # Done with this packet.
-        self.bitcount = self.databyte = 0
         self.bits = []
 
     def decode(self):
@@ -163,6 +166,7 @@ class Decoder(srd.Decoder):
             # Signal conditions tracked by the protocol decoder:
             # - RESET condition (R): RST = rising
             # - Incoming data (D): RST = low, CLK = rising.
+            #   TODO Add "RST low, CLK fall" for "end of DATA" here?
             # - Command mode START: CLK = high, I/O = falling.
             # - Command mode STOP: CLK = high, I/O = rising.
             (COND_RESET, COND_DATA, COND_CMD_START, COND_CMD_STOP,) = range(4)