From 749defd05add8a906cba9069a19598db61a7a52d Mon Sep 17 00:00:00 2001
From: Karol Stasiak <karol.m.stasiak@gmail.com>
Date: Tue, 24 Jul 2018 23:14:09 +0200
Subject: [PATCH] Decimal subtraction fixes

---
 src/main/scala/millfork/compiler/mos/BuiltIns.scala | 3 ++-
 src/main/scala/millfork/env/Constant.scala          | 8 +++++++-
 src/main/scala/millfork/parser/MfParser.scala       | 2 +-
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/main/scala/millfork/compiler/mos/BuiltIns.scala b/src/main/scala/millfork/compiler/mos/BuiltIns.scala
index 5f42ac95..18659fb0 100644
--- a/src/main/scala/millfork/compiler/mos/BuiltIns.scala
+++ b/src/main/scala/millfork/compiler/mos/BuiltIns.scala
@@ -825,6 +825,7 @@ object BuiltIns {
               if (l.+(1).quickSimplify == h) {
                 return List(AssemblyLine.zeropage(INC_W, l))
               }
+            case _ =>
           }
         }
         if (ctx.options.flags(CompilationFlag.EmitNative65816Opcodes)) {
@@ -1016,7 +1017,7 @@ object BuiltIns {
           ???
         }
         buffer ++= staTo(LDA, targetBytes(i))
-        buffer ++= ldTo(SBC, addendByteRead(i))
+        buffer ++= wrapInSedCldIfNeeded(decimal, ldTo(SBC, addendByteRead(i)))
         buffer ++= targetBytes(i)
       } else {
         if (i >= addendSize) {
diff --git a/src/main/scala/millfork/env/Constant.scala b/src/main/scala/millfork/env/Constant.scala
index 7aae9d87..359669ef 100644
--- a/src/main/scala/millfork/env/Constant.scala
+++ b/src/main/scala/millfork/env/Constant.scala
@@ -232,6 +232,9 @@ case class CompoundConstant(operator: MathOperator.Value, lhs: Constant, rhs: Co
       case (_, CompoundConstant(MathOperator.Plus, a, b)) if operator == MathOperator.Minus =>
         ((l - a) - b).quickSimplify
       case (CompoundConstant(MathOperator.Shl, SubbyteConstant(c1, 1), NumericConstant(8, _)), SubbyteConstant(c2, 0)) if operator == MathOperator.Or && c1 == c2 => c1
+
+      case (_, CompoundConstant(MathOperator.DecimalMinus, a, b)) if operator == MathOperator.DecimalPlus =>
+        CompoundConstant(MathOperator.DecimalMinus, CompoundConstant(MathOperator.DecimalPlus, l, a), b).quickSimplify
       case (NumericConstant(lv, ls), NumericConstant(rv, rs)) =>
         var size = ls max rs
         val value = operator match {
@@ -247,7 +250,9 @@ case class CompoundConstant(operator: MathOperator.Value, lhs: Constant, rhs: Co
           case MathOperator.Or => lv | rv
           case MathOperator.And => lv & rv
           case MathOperator.DecimalPlus if ls == 1 && rs == 1 =>
-            asDecimal(lv, rv, _ + _) & 0xff
+            asDecimal(lv & 0xff, rv & 0xff, _ + _) & 0xff
+          case MathOperator.DecimalMinus if ls == 1 && rs == 1 && lv.&(0xff) >= rv.&(0xff) =>
+            asDecimal(lv & 0xff, rv & 0xff, _ - _) & 0xff
           case _ => return this
         }
         operator match {
@@ -285,6 +290,7 @@ case class CompoundConstant(operator: MathOperator.Value, lhs: Constant, rhs: Co
           case MathOperator.DecimalPlus => c
           case MathOperator.DecimalPlus9 => c
           case MathOperator.Minus => c
+          case MathOperator.DecimalMinus => c
           case MathOperator.Times => Constant.Zero
           case MathOperator.Shl => c
           case MathOperator.Shr => c
diff --git a/src/main/scala/millfork/parser/MfParser.scala b/src/main/scala/millfork/parser/MfParser.scala
index 16b3b54d..280ba551 100644
--- a/src/main/scala/millfork/parser/MfParser.scala
+++ b/src/main/scala/millfork/parser/MfParser.scala
@@ -222,7 +222,7 @@ abstract class MfParser[T](fileId: String, input: String, currentDirectory: Stri
           case List("+") | List("-") | List("+", "-") | List("-", "+") =>
             SumExpression(xs.toPairList("+").map { case (op, value) => (op == "-", p(value, level + 1)) }, decimal = false)
           case List("+'") | List("-'") | List("+'", "-'") | List("-'", "+'") =>
-            SumExpression(xs.toPairList("+").map { case (op, value) => (op == "-", p(value, level + 1)) }, decimal = true)
+            SumExpression(xs.toPairList("+").map { case (op, value) => (op == "-'", p(value, level + 1)) }, decimal = true)
           case List(":") =>
             if (xs.size != 2) {
               ErrorReporting.error("The `:` operator can have only two arguments", xs.head.head.position)