nullptr

CHANGELOG.md

@@ -18,6 +18,8 @@
 
 * Pointers can now be typed.
 
+* Added `nullptr`.
+
 * Arrays can now have elements of types other than `byte` (still limited in size to 1 byte though).
 
 * Added hint for identifiers with typos.
@@ -36,7 +38,9 @@
 
 * Fixed `#use` not accessing all preprocessor parameters.
 
-* Fixed `#pragma` not respecting `#if`
+* Fixed `#pragma` not respecting `#if`.
+
+* 8080 and LR35902: fixed large stack variables.
 
 * Optimization improvements.
 

docs/lang/preprocessor.md

@@ -90,6 +90,8 @@ The following features are defined based on the chosen CPU and compilation optio
 
 * `PAL` – 1 if the target is PAL, 0 otherwise
 
+* `NULLPTR` – physical value of `nullptr`, default 0
+
 ### Built-in preprocessor functions and operators
 
 The `defined` function returns 1 if the feature is defined, 0 otherwise.  

docs/lang/types.md

@@ -66,6 +66,13 @@ Examples:
     p[i]        // valid only if the type 't' is of size 1, equivalent to 't(p.raw[i])'
     p->x        // valid only if the type 't' has a field called 'x', accesses the field 'x' of the pointed element
     p->x.y->z   // you can stack it
+  
+## `nullptr`
+
+There is a 2-byte constant `nullptr` that can be assigned to any 2-byte pointer type.
+Its actual value is defined using the feature `NULLPTR`, by default it's 0.
+
+`nullptr` isn't directly assignable to non-pointer types. 
 
 ## Boolean types
 
@@ -103,7 +110,7 @@ Assigment between numeric types and enumerations is not possible without an expl
 Plain enumerations have their variants equal to `byte(0)` to `byte(<name>.count - 1)`.
     
 Tip: You can use an enumeration with no variants as a strongly checked alternative byte type,
-as there are no checks no values when converting bytes to enumeration values and vice versa.
+as there are no checks on values when converting bytes to enumeration values and vice versa.
 
 ## Structs
 

src/main/scala/millfork/Main.scala

@@ -196,7 +196,7 @@ object Main {
     }
     val callGraph = new StandardCallGraph(program, options.log)
 
-    val env = new Environment(None, "", platform.cpuFamily, options.jobContext)
+    val env = new Environment(None, "", platform.cpuFamily, options)
     env.collectDeclarations(program, options)
 
     val assemblyOptimizations = optLevel match {
@@ -248,7 +248,7 @@ object Main {
     }
     val callGraph = new StandardCallGraph(program, options.log)
 
-    val env = new Environment(None, "", platform.cpuFamily, options.jobContext)
+    val env = new Environment(None, "", platform.cpuFamily, options)
     env.collectDeclarations(program, options)
 
     val assemblyOptimizations = optLevel match {

src/main/scala/millfork/compiler/AbstractExpressionCompiler.scala

@@ -28,7 +28,7 @@ class AbstractExpressionCompiler[T <: AbstractCode] {
   }
 
   def callingContext(ctx: CompilationContext, callee: String, v: VariableInMemory): CompilationContext = {
-    val result = new Environment(Some(ctx.env), "", ctx.options.platform.cpuFamily, ctx.jobContext)
+    val result = new Environment(Some(ctx.env), "", ctx.options.platform.cpuFamily, ctx.options)
     val localName = v.name.stripPrefix(callee + '$')
     result.addVariable(ctx.options, localName, v, None)
     ctx.copy(env = result)

src/main/scala/millfork/compiler/CompilationContext.scala

@@ -16,7 +16,7 @@ case class CompilationContext(env: Environment,
                               breakLabels: Map[String, Label] = Map(),
                               continueLabels: Map[String, Label] = Map()){
   def withInlinedEnv(environment: Environment, newLabel: String): CompilationContext = {
-    val newEnv = new Environment(Some(env), newLabel, environment.cpuFamily, jobContext)
+    val newEnv = new Environment(Some(env), newLabel, environment.cpuFamily, options)
     newEnv.things ++= environment.things
     copy(env = newEnv)
   }

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

@@ -18,8 +18,10 @@ import scala.collection.mutable.ListBuffer
   * @author Karol Stasiak
   */
 //noinspection NotImplementedCode
-class Environment(val parent: Option[Environment], val prefix: String, val cpuFamily: CpuFamily.Value, val jobContext: JobContext) {
+class Environment(val parent: Option[Environment], val prefix: String, val cpuFamily: CpuFamily.Value, val options: CompilationOptions) {
 
+  @inline
+  def jobContext: JobContext = options.jobContext
   @inline
   def log: Logger = jobContext.log
   @inline
@@ -50,7 +52,7 @@ class Environment(val parent: Option[Environment], val prefix: String, val cpuFa
         m.environment.getAllPrefixedThings
       case _ => Map[String, Thing]()
     }.fold(things.toMap)(_ ++ _)
-    val e = new Environment(None, "", cpuFamily, jobContext)
+    val e = new Environment(None, "", cpuFamily, options)
     e.things.clear()
     e.things ++= allThings
     e
@@ -397,6 +399,7 @@ class Environment(val parent: Option[Environment], val prefix: String, val cpuFa
 
   if (parent.isEmpty) {
     addThing(VoidType, None)
+    addThing(NullType, None)
     addThing(BuiltInBooleanType, None)
     val b = BasicPlainType("byte", 1)
     val w = BasicPlainType("word", 2)
@@ -433,8 +436,20 @@ class Environment(val parent: Option[Environment], val prefix: String, val cpuFa
     addThing(falseType, None)
     addThing(ConstantThing("true", NumericConstant(1, 0), trueType), None)
     addThing(ConstantThing("false", NumericConstant(0, 0), falseType), None)
-    addThing(ConstantThing("__zeropage_usage", UnexpandedConstant("__zeropage_usage", 1), b), None)
-    addThing(ConstantThing("__heap_start", UnexpandedConstant("__heap_start", 2), p), None)
+    val nullptrValue = options.features.getOrElse("NULLPTR", 0L)
+    val nullptrConstant = NumericConstant(nullptrValue, 2)
+    addThing(ConstantThing("nullptr", nullptrConstant, NullType), None)
+    addThing(ConstantThing("nullptr.hi", nullptrConstant.hiByte.quickSimplify, b), None)
+    addThing(ConstantThing("nullptr.lo", nullptrConstant.loByte.quickSimplify, b), None)
+    addThing(ConstantThing("nullptr.raw", nullptrConstant, p), None)
+    addThing(ConstantThing("nullptr.raw.hi", nullptrConstant.hiByte.quickSimplify, b), None)
+    addThing(ConstantThing("nullptr.raw.lo", nullptrConstant.loByte.quickSimplify, b), None)
+    val __zeropage_usage = UnexpandedConstant("__zeropage_usage", 1)
+    addThing(ConstantThing("__zeropage_usage", __zeropage_usage, b), None)
+    val __heap_start = UnexpandedConstant("__heap_start", 2)
+    addThing(ConstantThing("__heap_start", __heap_start, p), None)
+    addThing(ConstantThing("__heap_start.hi", __heap_start.hiByte, b), None)
+    addThing(ConstantThing("__heap_start.lo", __heap_start.loByte, b), None)
     addThing(ConstantThing("$0000", NumericConstant(0, 2), p), None)
     addThing(FlagBooleanType("set_carry",
       BranchingOpcodeMapping(Opcode.BCS, IfFlagSet(ZFlag.C)),
@@ -928,7 +943,7 @@ class Environment(val parent: Option[Environment], val prefix: String, val cpuFa
         log.error(s"Non-macro function `$name` cannot have inlinable parameters", stmt.position)
     }
 
-    val env = new Environment(Some(this), name + "$", cpuFamily, jobContext)
+    val env = new Environment(Some(this), name + "$", cpuFamily, options)
     stmt.params.foreach(p => env.registerParameter(p, options))
     def params: ParamSignature = if (stmt.assembly) {
       AssemblyParamSignature(stmt.params.map {

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

@@ -82,6 +82,20 @@ case class PointerType(name: String, targetName: String, var target: Option[Type
   override def pointerTargetName: String = targetName
 }
 
+case object NullType extends VariableType {
+  override def size: Int = 2
+
+  override def isSigned: Boolean = false
+
+  override def name: String = "null$"
+
+  override def isPointy: Boolean = true
+
+  override def isSubtypeOf(other: Type): Boolean = this == other || other.isPointy && other.size == 2
+
+  override def isAssignableTo(targetType: Type): Boolean = this == targetType || targetType.isPointy && targetType.size == 2
+}
+
 case class EnumType(name: String, count: Option[Int]) extends VariableType {
   override def size: Int = 1
 

src/test/scala/millfork/test/PointerSuite.scala

@@ -102,7 +102,7 @@ class PointerSuite extends FunSuite with Matchers {
         |
         | void main() {
         |   heapEnd = heap.addr
-        |   this = pointer.pointlist(0)
+        |   this = nullptr
         |   point tmp
         |   tmp.x = 3
         |   tmp.y = 3
@@ -152,4 +152,20 @@ class PointerSuite extends FunSuite with Matchers {
       m.readByte(0xc000) should equal(44)
     }
   }
+
+  test("nullptr") {
+    EmuUnoptimizedCrossPlatformRun(Cpu.Mos, Cpu.Z80)(
+      """
+        | void main() {
+        |   pointer.word pw
+        |   pointer p
+        |   word w
+        |   pw = nullptr
+        |   p = nullptr
+        |   w = word(nullptr)
+        | }
+      """.stripMargin) { m =>
+
+    }
+  }
 }

src/test/scala/millfork/test/ZLineSizeSuite.scala

@@ -17,8 +17,8 @@ class ZLineSizeSuite extends FunSuite with Matchers {
   private def runCase(line: ZLine): Unit = {
     val platform = EmuPlatform.get(Cpu.Z80)
     val jobContext = JobContext(TestErrorReporting.log, new LabelGenerator)
-    val env = new Environment(None, "", CpuFamily.I80, jobContext)
     val options = CompilationOptions(platform, Map(), None, 0, Map(), jobContext)
+    val env = new Environment(None, "", CpuFamily.I80, options)
     val correctSize = new Z80Assembler(null, env, platform).emitInstruction("default", options, 0x100, line) - 0x100
     val guessedSize = line.sizeInBytes
     guessedSize should equal(correctSize)

src/test/scala/millfork/test/emu/EmuRun.scala

@@ -185,7 +185,7 @@ class EmuRun(cpu: millfork.Cpu.Value, nodeOptimizations: List[NodeOptimization],
         }
         val program = nodeOptimizations.foldLeft(withLibraries.applyImportantAliases)((p, opt) => p.applyNodeOptimization(opt, options))
         val callGraph = new StandardCallGraph(program, log)
-        val env = new Environment(None, "", CpuFamily.M6502, options.jobContext)
+        val env = new Environment(None, "", CpuFamily.M6502, options)
         env.collectDeclarations(program, options)
 
         val hasOptimizations = assemblyOptimizations.nonEmpty
@@ -205,7 +205,7 @@ class EmuRun(cpu: millfork.Cpu.Value, nodeOptimizations: List[NodeOptimization],
 
 
         // compile
-        val env2 = new Environment(None, "", CpuFamily.M6502, options.jobContext)
+        val env2 = new Environment(None, "", CpuFamily.M6502, options)
         env2.collectDeclarations(program, options)
         val assembler = new MosAssembler(program, env2, platform)
         val output = assembler.assemble(callGraph, assemblyOptimizations, options)

src/test/scala/millfork/test/emu/EmuZ80Run.scala

@@ -109,7 +109,7 @@ class EmuZ80Run(cpu: millfork.Cpu.Value, nodeOptimizations: List[NodeOptimizatio
         }
         val program = nodeOptimizations.foldLeft(withLibraries.applyImportantAliases)((p, opt) => p.applyNodeOptimization(opt, options))
         val callGraph = new StandardCallGraph(program, log)
-        val env = new Environment(None, "", CpuFamily.I80, options.jobContext)
+        val env = new Environment(None, "", CpuFamily.I80, options)
         env.collectDeclarations(program, options)
 
         val hasOptimizations = assemblyOptimizations.nonEmpty
@@ -129,7 +129,7 @@ class EmuZ80Run(cpu: millfork.Cpu.Value, nodeOptimizations: List[NodeOptimizatio
 
 
         // compile
-        val env2 = new Environment(None, "", CpuFamily.I80, options.jobContext)
+        val env2 = new Environment(None, "", CpuFamily.I80, options)
         env2.collectDeclarations(program, options)
         val assembler = new Z80Assembler(program, env2, platform)
         val output = assembler.assemble(callGraph, assemblyOptimizations, options)

src/test/scala/millfork/test/emu/ShouldNotCompile.scala

@@ -45,7 +45,7 @@ object ShouldNotCompile extends Matchers {
         // prepare
         val callGraph = new StandardCallGraph(program, log)
         val cpuFamily = CpuFamily.forType(cpu)
-        val env = new Environment(None, "", cpuFamily, options.jobContext)
+        val env = new Environment(None, "", cpuFamily, options)
         env.collectDeclarations(program, options)
 
         var unoptimizedSize = 0L