increment range spec

src/main/scala/com/htmlism/mos6502/dsl/DslDemo.scala

@@ -74,26 +74,23 @@ object registers {
     def incr(implicit ctx: AssemblyContext): Unit =
       ctx.push(INX, "incr x")
 
-    def upTo(s: String, start: Int, stop: Int)(f: AssemblyContext => Unit)(implicit ctx: AssemblyContext): Unit = {
+    def loop(s: String, spec: RangeSpec)(f: AssemblyContext => Unit)(implicit ctx: AssemblyContext): Unit = {
+      val (start, stop, instruction) =
+        spec match {
+          case Incrementing(from, to) =>
+            (from, to, INX)
+
+          case Decrementing(from, to) =>
+            (from, to, DEX)
+        }
+
       ctx.push(LDX, start)
 
       label(s)
 
       f(ctx)
 
-      ctx.push(INX)
-      ctx.push(CPX, stop)
-      ctx.branch(BNE, s)
-    }
-
-    def downTo(s: String, start: Int, stop: Int)(f: AssemblyContext => Unit)(implicit ctx: AssemblyContext): Unit = {
-      ctx.push(LDX, start)
-
-      label(s)
-
-      f(ctx)
-
-      ctx.push(DEX)
+      ctx.push(instruction)
       ctx.push(CPX, stop)
       ctx.branch(BNE, s)
     }

src/main/scala/com/htmlism/mos6502/dsl/RangeSpec.scala

@@ -0,0 +1,11 @@
+package com.htmlism.mos6502.dsl
+
+sealed trait RangeSpec {
+  def from: Int
+
+  def to: Int
+}
+
+case class Incrementing(from: Int, to: Int) extends RangeSpec
+
+case class Decrementing(from: Int, to: Int) extends RangeSpec

src/main/scala/com/htmlism/mos6502/dsl/package.scala

@@ -17,4 +17,12 @@ package object dsl extends syntax.DefinitionGroupSyntax with syntax.AsmDocSyntax
     def addr: GlobalAddress =
       GlobalAddress(n)
   }
+
+  implicit class RangeOps(from: Int) {
+    def upTo(to: Int): Incrementing =
+      Incrementing(from, to)
+
+    def downTo(to: Int): Decrementing =
+      Decrementing(from, to)
+  }
 }

src/test/scala/com/htmlism/mos6502/dsl/Easy6502Spec.scala

@@ -55,7 +55,7 @@ class Easy6502Spec extends AnyFlatSpec with should.Matchers {
     val doc =
       asmDoc { implicit ctx =>
         asm { implicit a =>
-          registers.X.upTo("incrementing", 2, 5) { implicit a =>
+          registers.X.loop("incrementing", 2 upTo 5) { implicit a =>
             a.push(INY)
           }
         }