Implement ECALL and EBREAK, the final RV64I instructions!

src/instructions.rs

@@ -13,7 +13,10 @@ use crate::{
     consts::DWord,
     core::Core,
     decode::Instruction,
-    exceptions::{Exception, ExceptionType::IllegalInstruction},
+    exceptions::{
+        Exception,
+        ExceptionType::{self, IllegalInstruction},
+    },
 };
 
 fn illegal(instr: Instruction) -> Result<(), Exception> {
@@ -130,6 +133,15 @@ pub(crate) fn find_and_exec(instr: Instruction, core: &mut Core) -> Result<(), E
             }
             _ => illegal(instr),
         },
+        0b11100 => match (instr.funct3(), instr.funct12(), instr.rs1(), instr.rd()) {
+            (0b000, 0b000000000000, 0, 0) => {
+                // TODO: When privilege modes are added, make the exception raised by ecall
+                // depend on privilege mode
+                Err(ExceptionType::EnvironmentCallFromMMode.with_no_value())
+            }
+            (0b000, 0b000000000001, 0, 0) => Err(ExceptionType::Breakpoint.with_no_value()),
+            _ => illegal(instr),
+        },
         _ => illegal(instr),
     }
 }