Add HID classes

usb_protocol/emitters/descriptors/hid.py

@@ -0,0 +1,41 @@
+import unittest
+
+from contextlib import contextmanager
+
+from ..           import emitter_for_format
+from ..descriptor import ComplexDescriptorEmitter
+from ...types.descriptors.hid import *
+
+class HIDDescriptorEmitter(ComplexDescriptorEmitter):
+
+    DESCRIPTOR_FORMAT = HIDDescriptor
+
+    @contextmanager
+    def DescriptorReference(self):
+        """ Context manager that allows addition of a descriptor reference.
+
+        It can be used with a `with` statement; and yields an HIDDescriptorReferenceEmitter
+        that can be populated:
+
+            with hiddescriptor.DescriptorReference() as r:
+                r.bDescriptorType = 0x22
+                r.wDescriptorLength = 0x10
+                r.wDescriptorLength = 0x10
+
+        This adds the relevant descriptor reference, automatically.
+        """
+
+        descriptor = HIDDescriptorReferenceEmitter()
+        yield descriptor
+
+        self.add_subordinate_descriptor(descriptor)
+
+    def _pre_emit(self):
+        # Figure out the total length of our descriptor, including subordinates.
+        subordinate_length = sum(len(sub) for sub in self._subordinates)
+        self.bLength = subordinate_length + self.DESCRIPTOR_FORMAT.sizeof()
+        self.bNumDescriptors = len(self._subordinates)
+        pass
+
+
+HIDDescriptorReferenceEmitter = emitter_for_format(HIDDescriptorReference)

usb_protocol/types/descriptors/hid.py

@@ -0,0 +1,46 @@
+#
+# This file is part of usb-protocol.
+#
+""" Structures describing Human Interface Device Class descriptors. """
+
+import unittest
+from enum import IntEnum
+
+from ..descriptor import \
+    DescriptorField, DescriptorNumber, DescriptorFormat
+
+class HidInterfaceClassCodes(IntEnum):
+    HID = 0x03
+
+class HidInterfaceSubclassCodes(IntEnum):
+    NO_SUBCLASS = 0
+    BOOT        = 1
+
+class HidInterfaceProtocols(IntEnum):
+    NONE     = 0
+    KEYBOARD = 1
+    MOUSE    = 2
+
+class HidClassSpecificDescriptorTypes(IntEnum):
+    CS_UNDEFINED     = 0x20
+    CS_HID           = 0x21
+    CS_REPORT        = 0x22
+    CS_PHYSICAL      = 0x23
+
+
+HIDDescriptor = DescriptorFormat(
+    "bLength"             / DescriptorField("Descriptor Length"),
+    "bDescriptorType"     / DescriptorNumber(HidClassSpecificDescriptorTypes.CS_HID),
+    "bcdHID"              / DescriptorField("HID Protocol Version", default=1.11),
+    "bCountryCode"        / DescriptorField("Hardware target country", default=0),
+    "bNumDescriptors"     / DescriptorField("Number of HID class descriptors to follow", default=0),
+)
+
+# This is not really a stand-alone descriptor, but rather a reference to a descriptor
+# that can be retrieved seperately. It is part of the HIDDescriptor above.  The HID
+# descriptor can contain multiple descriptor references. To support this, a separate
+# descriptor format is used.
+HIDDescriptorReference = DescriptorFormat(
+    "bDescriptorType"     / DescriptorField("HID Descriptor Type", default=HidClassSpecificDescriptorTypes.CS_REPORT),
+    "wDescriptorLength"   / DescriptorField("HID Descriptor Length")
+)