Make more elements optional, support other field definition types

__init__.py

@@ -24,11 +24,18 @@ def import_svd(bv: BinaryView):
 
     for peripheral in peripherals:
         per_name: str = peripheral['name']
-        per_desc: str = peripheral['description']
+        per_desc = None
+        if 'description' in peripheral:
+            per_desc: str = peripheral['description']
         per_base_addr: int = peripheral['baseAddress']
         per_struct = StructureBuilder.create()
 
-        per_registers = peripheral['registers']['register']
+        # the registers block is an optional 0..1 field in the SVD spec. Even
+        # if we don't get individual register definitions, we can create a
+        # memory region for a peripheral
+        per_registers = []
+        if 'registers' in peripheral:
+            per_registers = peripheral['registers']['register']
         for register in per_registers:
             reg_name: str = register['name']
             reg_desc: str = register['description']
@@ -41,8 +48,22 @@ def import_svd(bv: BinaryView):
             reg_fields = register['fields']['field']
             for field in reg_fields:
                 field_name: str = field['name']
-                field_lsb: int = field['lsb']
-                field_msb: int = field['msb']
+                # one of the three following field bit specifications must be
+                # provided
+                if 'lsb' in field and 'msb' in field:
+                    field_lsb: int = field['lsb']
+                    field_msb: int = field['msb']
+                elif 'bitOffset' in field:
+                    field_lsb: int = field['bitOffset']
+                    # The bitWidth field is optional
+                    if 'bitWidth' in field:
+                        field_msb: int = field['bitOffset'] + field['bitWidth'] - 1
+                    else:
+                        field_msb: int = field['bitOffset']
+                elif 'bitRange' in field:
+                    msb_str, lsb_str = field['bitRange'].split(':', 1)
+                    field_lsb: int = int(lsb_str[:-1])
+                    field_msb: int = int(msb_str[1:])
                 field_lsb_b: float = field_lsb / BYTE_SIZE
                 field_msb_b: float = field_msb / BYTE_SIZE
 
@@ -102,7 +123,7 @@ def import_svd(bv: BinaryView):
         bv.memory_map.add_memory_region(per_name, per_base_addr, bytearray(per_size))
 
         # Add the peripheral description as a comment
-        if show_comments:
+        if show_comments and per_desc is not None:
             bv.set_comment_at(per_base_addr, per_desc)
         # Define the peripheral type and data var in the binary view.
         per_struct_ty = Type.structure_type(per_struct)