add sigrok decoder for the pixart PMW protocol

Author: t-8ch

tools/libsigrokdecode/pixart-pmw/__init__.py

@@ -0,0 +1 @@
+from .pd import Decoder

tools/libsigrokdecode/pixart-pmw/pd.py

@@ -0,0 +1,75 @@
+import enum
+
+import sigrokdecode as srd
+
+__all__ = ['Decoder']
+
+
+class RegisterOperation(enum.Enum):
+    READ = enum.auto()
+    WRITE = enum.auto()
+
+
+class Decoder(srd.Decoder):
+    api_version = 3
+    id = 'pixart-pmw'
+    name = 'PixArt PMW'
+    license = 'gplv2+'
+    longname = 'PixArt PMW protocol over SPI'
+    desc = (
+            'Decoder for protocol used to communicate '
+            'with PixArt PMW chips over SPI'
+    )
+    inputs = ['spi']
+    outputs = []
+    annotations = (
+        ('command', 'Command'),
+        ('reply', 'Reply'),
+    )
+    annotation_rows = (
+        ('command', 'Command', (0, )),
+        ('reply', 'Reply', (1, )),
+    )
+
+    def __init__(self):
+        self.reset()
+
+    def start(self):
+        self.out_ann = self.register(srd.OUTPUT_ANN)
+
+    def reset(self):
+        pass
+
+    def decode(self, startsample, endsample, data):
+        ptype, command_data, reply_data = data
+
+        if ptype != 'TRANSFER':
+            return
+
+        if not command_data:
+            return
+
+        first_byte = command_data[0].val
+        command_type = RegisterOperation.WRITE if first_byte & 0x80 else RegisterOperation.READ
+        register_num = first_byte & ~0x80
+
+        command_end = endsample
+        if command_type == RegisterOperation.READ:
+            message = 'Read register {:02X}'.format(register_num)
+            if len(command_data) > 1:
+                command_end = command_data[1].ss
+        elif command_type == RegisterOperation.WRITE:
+            message = 'Write register {:02X}: {}'.format(
+                register_num, format_transfer_data(command_data[1:]))
+        self.put(startsample, command_end, self.out_ann, [0, [message]])
+
+        if command_type == RegisterOperation.READ:
+            reply_start = startsample
+            if len(reply_data) > 1:
+                reply_start = reply_data[1].ss
+            self.put(reply_start, endsample, self.out_ann,
+                     [1, [format_transfer_data(reply_data[1:])]])
+
+
+def format_transfer_data(data):
+    return ' '.join(['{:02X}'.format(val.val) for val in data])