refactor: removes magic numbers in asmgenerator

src/main/wacc/backend/RuntimeError.scala

@@ -3,8 +3,6 @@ package wacc
 import cats.data.Chain
 import wacc.assemblyIR._
 
-val ERROR_CODE = 255
-
 sealed trait RuntimeError {
   def strLabel: String
   def errStr: String
@@ -28,14 +26,11 @@ object RuntimeError {
   import assemblyIR.Size._
   import assemblyIR.RegName._
 
-  // private val RAX = Register(Q64, AX)
-  // private val EAX = Register(D32, AX)
   private val RDI = Register(Q64, DI)
   private val RIP = Register(Q64, IP)
-  // private val RBP = Register(Q64, BP)
   private val RSI = Register(Q64, SI)
-  // private val RDX = Register(Q64, DX)
   private val RCX = Register(Q64, CX)
+  private val ERROR_CODE = 255
 
   case object ZeroDivError extends RuntimeError {
     val strLabel = ".L._errDivZero_str0"

src/main/wacc/backend/asmGenerator.scala

@@ -25,6 +25,8 @@ object asmGenerator {
   private val ECX = Register(D32, CX)
   private val argRegs = List(DI, SI, DX, CX, R8, R9)
 
+  private val _7_BIT_MASK = 0x7f
+
   extension [T](chain: Chain[T])
     def +(item: T): Chain[T] = chain.append(item)
 
@@ -326,7 +328,7 @@ object asmGenerator {
         op match {
           case UnaryOperator.Chr =>
             chain += Move(EAX, stack.head)
-            chain += And(EAX, ImmediateVal(-128))
+            chain += And(EAX, ImmediateVal(~_7_BIT_MASK))
             chain += Compare(EAX, ImmediateVal(0))
             chain += Jump(LabelArg(BadChrError.errLabel), Cond.NotEqual)
           case UnaryOperator.Ord => // No op needed