1 files changed, 24 insertions, 4 deletions
diff --git a/src/error/mod.rs b/src/error/mod.rs
index 99f78bb..b6c1e24 100644
--- a/src/error/mod.rs
+++ b/src/error/mod.rs
@@ -27,9 +27,23 @@ pub type Result<T> = core::result::Result<T, Error>;
 /// A crate error.
 #[derive(Clone, Debug)]
 pub enum Error {
- ImmediateTooLarge,
+ /// The given immediate cannot be encoded.
+ IllegalImmediate,
 
- InvalidImmediateValue,
+ /// The given instruction cannot be encoded.
+ ///
+ /// Even valid instructions are not valid in *every* case.
+ /// For example, most shifter operands and instruction predicates are **not** allowed in a Thumb context (with exceptions).
+ IllegalInstruction,
+
+ /// The given instruction predicate cannot be encoded.
+ IllegalPredicate,
+
+ /// The given register can currently not be used.
+ IllegalRegister,
+
+ /// Register name is not known.
+ UnknownRegister,
 }
 
 impl Display for Error {
@@ -37,9 +51,15 @@ impl Display for Error {
 use Error::*;
 
 let message = match *self {
- ImmediateTooLarge => "immediate too large",
+ IllegalImmediate => "illegal immediate value",
+
+ IllegalInstruction => "illegal instruction",
+
+ IllegalPredicate => "illegal instruction predicate",
+
+ IllegalRegister => "register not permitted here",
 
- InvalidImmediateValue => "invalid immediate value",
+ UnknownRegister => "unknown register",
 };
 
 f.write_str(message)