diff --git a/src/parser.rs b/src/parser.rs
index 5bd88ef..30c0cea 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -47,10 +47,14 @@ pub enum Ast {
 /*
 ## Grammar
 ### Expressions
-`expr_primary = LITERAL` \
-`expr_mul = expr_primary (("*" | "/") expr_primary)*` \
-`expr_add = expr_mul (("+" | "-") expr_mul)*` \
-`expr = expr_add` \
+expr_primary = LITERAL
+expr_mul = expr_primary (("*" | "/" | "%") expr_primary)*
+expr_add = expr_mul (("+" | "-") expr_mul)*
+expr_shift = expr_add ((">>" | "<<") expr_add)*
+expr_band = expr_shift ("&" expr_shift)*
+expr_bxor = expr_band ("^") expr_band)*
+expr_bor = expr_bxor ("|" expr_bxor)*
+expr = expr_bor
 */
 
 struct Parser<T: Iterator<Item = Token>> {
@@ -129,6 +133,10 @@ pub fn parse<T: Iterator<Item = Token>, A: IntoIterator<IntoIter = T>>(tokens: A
 impl BinOpType {
     /// Get the precedence for a binary operator. Higher value means the OP is stronger binding.
     /// For example Multiplication is stronger than addition, so Mul has higher precedence than Add.
+    /// 
+    /// The operator precedences are derived from the C language operator precedences. While not all
+    /// C operators are included or the exact same, the precedence oder is the same. 
+    /// See: https://en.cppreference.com/w/c/language/operator_precedence
     fn precedence(&self) -> u8 {
         match self {
             BinOpType::BOr => 0,