Interrupt functions in assembly should not have prologue (fixes #62)

src/main/scala/millfork/compiler/mos/MosCompiler.scala

@@ -37,7 +37,7 @@ object MosCompiler extends AbstractCompiler[AssemblyLine] {
         List(AssemblyLine.absolute(LDA, ctx.env.get[ThingInMemory]("__sp")), AssemblyLine.implied(PHA))
       } else Nil)
 
-    val prefix = storeParamsFromRegisters ++ (if (ctx.function.interrupt) {
+    val prefix = storeParamsFromRegisters ++ (if (ctx.function.interrupt && !ctx.function.inAssembly) {
 
       if (ctx.options.flag(CompilationFlag.EmitNative65816Opcodes)) {
         if (zpRegisterSize > 0) {

src/main/scala/millfork/compiler/z80/Z80Compiler.scala

@@ -68,7 +68,7 @@ object Z80Compiler extends AbstractCompiler[ZLine] {
   def preserveRegisters(ctx: CompilationContext): List[ZLine] = {
     import millfork.assembly.z80.ZOpcode._
     import ZRegister._
-    if (ctx.function.interrupt) {
+    if (ctx.function.interrupt && !ctx.function.inAssembly) {
       if (ctx.options.flag(CompilationFlag.EmitZ80Opcodes)) {
         if (ctx.options.flag(CompilationFlag.UseShadowRegistersForInterrupts)) {
           List(

src/main/scala/millfork/env/Environment.scala

@@ -1378,6 +1378,7 @@ class Environment(val parent: Option[Environment], val prefix: String, val cpuFa
             hasElidedReturnVariable = hasElidedReturnVariable,
             interrupt = stmt.interrupt,
             kernalInterrupt = stmt.kernalInterrupt,
+            inAssembly = stmt.assembly,
             reentrant = stmt.reentrant,
             isConstPure = stmt.constPure,
             position = stmt.position,

src/main/scala/millfork/env/Thing.scala

@@ -481,6 +481,7 @@ case class NormalFunction(name: String,
                           hasElidedReturnVariable: Boolean,
                           interrupt: Boolean,
                           kernalInterrupt: Boolean,
+                          inAssembly: Boolean,
                           isConstPure: Boolean,
                           reentrant: Boolean,
                           position: Option[Position],

src/test/scala/millfork/test/AssemblySuite.scala

@@ -460,4 +460,49 @@ class AssemblySuite extends FunSuite with Matchers with AppendedClues {
     m.readByte(0xc001) should equal(1)
     m.readByte(0xc002) should equal(2)
   }
+
+  test("Interrupt functions in assembly should not have prologue (6502)") {
+    val m = EmuUnoptimizedRun(
+      """
+        |byte output @$c000
+        |noinline interrupt asm void i() {
+        |  nop
+        |  rti
+        |}
+        |void main() {
+        |   output = pointer(i.addr)[0]
+        |}
+        |""".stripMargin)
+    m.readByte(0xc000) should equal(0xea)
+  }
+
+  test("Interrupt functions in assembly should not have prologue (Z80)") {
+    val m = EmuUnoptimizedZ80Run(
+      """
+        |byte output @$c000
+        |noinline interrupt asm void i() {
+        |  nop
+        |  reti
+        |}
+        |void main() {
+        |   output = pointer(i.addr)[0]
+        |}
+        |""".stripMargin)
+    m.readByte(0xc000) should equal(0)
+  }
+
+  test("Interrupt functions in assembly should not have prologue (M6809)") {
+    val m = EmuUnoptimizedM6809Run(
+      """
+        |byte output @$c000
+        |noinline interrupt asm void i() {
+        |  nop
+        |  rti
+        |}
+        |void main() {
+        |   output = pointer(i.addr)[0]
+        |}
+        |""".stripMargin)
+    m.readByte(0xc000) should equal(0x12)
+  }
 }