Added enums and bitfields

Pattern-Language-Guide.md

@@ -91,4 +91,55 @@ union Color {
 Color color @ 0x100;
 ```
 
-![Union](https://puu.sh/H4LY2/0d40d2ac34.png)
+![Union](https://puu.sh/H4LY2/0d40d2ac34.png)
+
+## Enums
+
+Enums are types whose value is restricted to a distinct number of values. When placed in memory, the Pattern Data View will show the relevant enum entry name instead of the numerical value. 
+
+Every enum has an underlying type which is used to specify the size of the enum when placed in memory. `u32` will create a 4 byte enum, `s8` will create a 1 byte enum.
+
+Every enum entry can be set to a distinct value using the `<identifier> = <expression>` syntax as seen below. If no value is specified for an entry, it's value will be the value of the last entry plus one. Counting starts at zero.
+
+```cpp
+enum <typeName> : <builtinTypeName> {
+  <enumEntry>
+  ...
+};
+
+// Example
+enum Architecture : u8 {
+  x86 = 0x20,
+  x64, // Value 0x21
+  ARM32 = 0x35,
+  ARM64 // Value 0x36
+};
+
+Architecture arch @ 0x100;
+```
+
+![Enum](https://puu.sh/H4Mx6/c1761deddd.png)
+
+## Bitfields
+
+If you're trying to parse a region of memory that is not aligned to the usual 8 bit boundaries or has variables that are smaller than one 8 bits (such as bit flags), a bitfield can be used.
+Bitfields allow variables to be specified with a custom number bits used. This is done by using the `<identifier> : <expression>` syntax where the identifier before the colon specifies the field name and the expression after the colon the size of the field in bits.
+There is no padding inserted between members, however the size of the entire bitfield will be rounded up to the next 8 bit boundary.
+
+```cpp
+bitfield <typeName> {
+  <bitfieldEntry>
+  ...
+};
+
+// Example
+bitfield Permission {
+  r : 1;
+  w : 1;
+  x : 1;
+};
+
+Permission perm @ 0x20;
+```
+
+![Bitfields](https://puu.sh/H4MC9/24980dcaae.png)