srd: SPI: Add support for arbitrary word sizes.

[libsigrokdecode.git] / decoders / spi.py

diff --git a/decoders/spi.py b/decoders/spi.py
index 2f692f08f28c40ffce6ceed0ed0f1e59b7d0554a..7c56aed6fb3a2aa60a62e9327a9a242e8bb49105 100644 (file)
--- a/decoders/spi.py
+++ b/decoders/spi.py
@@ -35,7 +35,7 @@ CPHA_1 = 1 # Data is valid on the falling clock edge
 
 # Bit order options
 MSB_FIRST = 0
-LSB_FIRST = 0
+LSB_FIRST = 1
 
 # Annotation formats
 ANN_HEX = 0
@@ -78,6 +78,13 @@ class Decoder(srd.Decoder):
         self.bytesreceived = 0
         self.samplenum = -1
 
+        # Set protocol decoder option defaults.
+        self.cs_active_low = Decoder.options['cs_active_low'][1]
+        self.clock_polarity = Decoder.options['clock_polarity'][1]
+        self.clock_phase = Decoder.options['clock_phase'][1]
+        self.bit_order = Decoder.options['bit_order'][1]
+        self.word_size = Decoder.options['word_size'][1]
+
     def start(self, metadata):
         self.out_proto = self.add(srd.OUTPUT_PROTO, 'spi')
         self.out_ann = self.add(srd.OUTPUT_ANN, 'spi')
@@ -105,16 +112,22 @@ class Decoder(srd.Decoder):
             if self.bitcount == 0:
                 self.start_sample = samplenum
 
-            # Receive bit into our shift register.
-            if mosi == 1:
-                self.mosidata |= 1 << (7 - self.bitcount)
-            if miso == 1:
-                self.misodata |= 1 << (7 - self.bitcount)
+            # Receive MOSI bit into our shift register.
+            if self.bit_order == MSB_FIRST:
+                self.mosidata |= mosi << (self.wordsize - 1 - self.bitcount)
+            else:
+                self.mosidata |= mosi << self.bitcount
+
+            # Receive MISO bit into our shift register.
+            if self.bit_order == MSB_FIRST:
+                self.misodata |= miso << (self.wordsize - 1 - self.bitcount)
+            else:
+                self.misodata |= miso << self.bitcount
 
             self.bitcount += 1
 
             # Continue to receive if not a byte yet.
-            if self.bitcount != 8:
+            if self.bitcount != self.wordsize:
                 continue
 
             self.put(self.start_sample, self.samplenum, self.out_proto,