X-Git-Url: https://sigrok.org/gitweb/?p=libsigrokdecode.git;a=blobdiff_plain;f=decoders%2Fspi%2Fpd.py;h=25a9f85f9c059b662fefd203f7e364fdd0edfbb2;hp=1ddb119c2729f1c2ff15972db887fc4482e8f15d;hb=1c49e875623918f8893308307f487a1f551daec4;hpb=4fecc5a4bcb036f40e23ab967579334076203c2f

diff --git a/decoders/spi/pd.py b/decoders/spi/pd.py
index 1ddb119..25a9f85 100644
--- a/decoders/spi/pd.py
+++ b/decoders/spi/pd.py
@@ -28,14 +28,16 @@ Packet:
 [<ptype>, <data1>, <data2>]
 
 <ptype>:
- - 'DATA': <data1> contains the MISO data, <data2> contains the MOSI data.
+ - 'DATA': <data1> contains the MOSI data, <data2> contains the MISO data.
    The data is _usually_ 8 bits (but can also be fewer or more bits).
    Both data items are Python numbers (not strings), or None if the respective
    channel was not supplied.
- - 'BITS': <data1>/<data2> contain a list of bit values in this MISO/MOSI data
+ - 'BITS': <data1>/<data2> contain a list of bit values in this MOSI/MISO data
    item, and for each of those also their respective start-/endsample numbers.
  - 'CS CHANGE': <data1> is the old CS# pin value, <data2> is the new value.
-   Both data items are Python numbers (0/1), not strings.
+   Both data items are Python numbers (0/1), not strings. At the beginning of
+   the decoding a packet is generated with <data1> = -1 and <data2> being the
+   initial state of the CS# pin or -1 if the chip select pin is not supplied.
 
 Examples:
  ['CS-CHANGE', 1, 0]
@@ -60,6 +62,12 @@ spi_mode = {
     (1, 1): 3, # Mode 3
 }
 
+class SamplerateError(Exception):
+    pass
+
+class ChannelError(Exception):
+    pass
+
 class Decoder(srd.Decoder):
     api_version = 2
     id = 'spi'
@@ -110,12 +118,13 @@ class Decoder(srd.Decoder):
         self.misodata = self.mosidata = 0
         self.misobits = []
         self.mosibits = []
-        self.startsample = -1
+        self.ss_block = -1
         self.samplenum = -1
         self.cs_was_deasserted = False
         self.oldcs = -1
         self.oldpins = None
         self.have_cs = self.have_miso = self.have_mosi = None
+        self.no_cs_notification = False
 
     def metadata(self, key, value):
         if key == srd.SRD_CONF_SAMPLERATE:
@@ -128,7 +137,7 @@ class Decoder(srd.Decoder):
                 meta=(int, 'Bitrate', 'Bitrate during transfers'))
 
     def putw(self, data):
-        self.put(self.startsample, self.samplenum, self.out_ann, data)
+        self.put(self.ss_block, self.samplenum, self.out_ann, data)
 
     def putdata(self):
         # Pass MISO and MOSI bits and then data to the next PD up the stack.
@@ -169,7 +178,7 @@ class Decoder(srd.Decoder):
     def handle_bit(self, miso, mosi, clk, cs):
         # If this is the first bit of a dataword, save its sample number.
         if self.bitcount == 0:
-            self.startsample = self.samplenum
+            self.ss_block = self.samplenum
             self.cs_was_deasserted = False
             if self.have_cs:
                 active_low = (self.options['cs_polarity'] == 'active-low')
@@ -219,9 +228,9 @@ class Decoder(srd.Decoder):
 
         # Meta bitrate.
         elapsed = 1 / float(self.samplerate)
-        elapsed *= (self.samplenum - self.startsample + 1)
+        elapsed *= (self.samplenum - self.ss_block + 1)
         bitrate = int(1 / elapsed * self.options['wordsize'])
-        self.put(self.startsample, self.samplenum, self.out_bitrate, bitrate)
+        self.put(self.ss_block, self.samplenum, self.out_bitrate, bitrate)
 
         if self.have_cs and self.cs_was_deasserted:
             self.putw([4, ['CS# was deasserted during this data word!']])
@@ -258,8 +267,8 @@ class Decoder(srd.Decoder):
         self.handle_bit(miso, mosi, clk, cs)
 
     def decode(self, ss, es, data):
-        if self.samplerate is None:
-            raise Exception("Cannot decode without samplerate.")
+        if not self.samplerate:
+            raise SamplerateError('Cannot decode without samplerate.')
         # Either MISO or MOSI can be omitted (but not both). CS# is optional.
         for (self.samplenum, pins) in data:
 
@@ -273,7 +282,11 @@ class Decoder(srd.Decoder):
 
             # Either MISO or MOSI (but not both) can be omitted.
             if not (self.have_miso or self.have_mosi):
-                raise Exception('Either MISO or MOSI (or both) pins required.')
+                raise ChannelError('Either MISO or MOSI (or both) pins required.')
 
-            self.find_clk_edge(miso, mosi, clk, cs)
+            # Tell stacked decoders that we don't have a CS# signal.
+            if not self.no_cs_notification and not self.have_cs:
+                self.put(0, 0, self.out_python, ['CS-CHANGE', -1, -1])
+                self.no_cs_notification = True
 
+            self.find_clk_edge(miso, mosi, clk, cs)