Add ability to specify size of generated enums

2 files changed, 18 insertions, 3 deletions

diff --git a/docs/reference.md b/docs/reference.md
index c86330e..720e679 100644
--- a/docs/reference.md
+++ b/docs/reference.md
@@ -50,7 +50,7 @@ The full set of available options is defined in [nanopb.proto](https://github.co
 * `fixed_length`: Generate `bytes` fields with a constant length defined by `max_size`. A separate `.size` field will then not be generated.
 * `fixed_count`: Generate arrays with constant length defined by `max_count`.
 * `package`: Package name that applies only for nanopb generator. Defaults to name defined by `package` keyword in .proto file, which applies for all languages.
-* `int_size`: Override the integer type of a field. For example, specify `int_size = IS_8` to convert `int32` from protocol definition into `int8_t` in the structure.
+* `int_size`: Override the integer type of a field. For example, specify `int_size = IS_8` to convert `int32` from protocol definition into `int8_t` in the structure. When used with enum types, the size of the generated enum can be specified (C++ only)
 
 These options can be defined for the .proto files before they are
 converted using the nanopb-generator.py. There are three ways to define
diff --git a/generator/nanopb_generator.py b/generator/nanopb_generator.py
index 3b79948..8dc0e80 100755
--- a/generator/nanopb_generator.py
+++ b/generator/nanopb_generator.py
@@ -99,7 +99,11 @@ datatypes = {
     FieldD.TYPE_UINT32:     ('uint32_t', 'UINT32',      5,  4),
     FieldD.TYPE_UINT64:     ('uint64_t', 'UINT64',     10,  8),
 
-    # Integer size override options
+    # Integer size override option
+    (FieldD.TYPE_ENUM,    nanopb_pb2.IS_8):   ('uint8_t', 'ENUM',  4,  1),
+    (FieldD.TYPE_ENUM,   nanopb_pb2.IS_16):   ('uint16_t', 'ENUM',  4,  2),
+    (FieldD.TYPE_ENUM,   nanopb_pb2.IS_32):   ('uint32_t', 'ENUM',  4,  4),
+    (FieldD.TYPE_ENUM,   nanopb_pb2.IS_64):   ('uint64_t', 'ENUM',  4,  8),
     (FieldD.TYPE_INT32,   nanopb_pb2.IS_8):   ('int8_t',   'INT32', 10,  1),
     (FieldD.TYPE_INT32,  nanopb_pb2.IS_16):   ('int16_t',  'INT32', 10,  2),
     (FieldD.TYPE_INT32,  nanopb_pb2.IS_32):   ('int32_t',  'INT32', 10,  4),
@@ -431,7 +435,18 @@ class Enum(ProtoElement):
         if leading_comment:
             result = '%s\n' % leading_comment
 
-        result += 'typedef enum %s {' % Globals.naming_style.enum_name(self.names)
+        result += 'typedef enum %s' % Globals.naming_style.enum_name(self.names)
+
+        # Override the enum size if user wants to use smaller integers
+        if (FieldD.TYPE_ENUM, self.options.int_size) in datatypes:
+            self.ctype, self.pbtype, self.enc_size, self.data_item_size = datatypes[(FieldD.TYPE_ENUM, self.options.int_size)]
+            result += '\n#ifdef __cplusplus\n'
+            result += ' : ' + self.ctype + '\n'
+            result += '#endif\n'
+            result += '{'
+        else:
+            result += ' {'
+
         if trailing_comment:
             result += " " + trailing_comment