Allow defining free zeropage bytes instead of pointers

CHANGELOG.md

@@ -50,6 +50,8 @@
 
 * **Potentially breaking change!** Commodore 128 target no longer defines `CBM_64` feature.
 
+* 6502 targets can now define free zeropage bytes, not only pointers.
+
 * 6502: Fixed optimizations using index registers.
 
 * 6502: Fixed optimizations of comparisons.

docs/api/custom-platform.md

@@ -118,7 +118,11 @@ See the [preprocessor documentation](../lang/preprocessor.md) for more info.
 * `zp_pointers` – 
 either a list of comma separated zeropage addresses that can be used by the program as zeropage pointers, or `all` for all. 
 Each value should be the address of the first of two free bytes in the zeropage.
-Only used for 6502-based targets.
+Only used for 6502-based targets. Cannot be used together with `zp_bytes`.
+
+* `zp_bytes` – 
+either a list of comma separated zeropage byte addresses or address ranges that can be used by the program in zeropage, or `all` for all. 
+Only used for 6502-based targets. Cannot be used together with `zp_pointers`.
 
 * `segments` – a comma-separated list of segment names.  
 A segment named `default` is always required.  

include/a8.ini

@@ -5,7 +5,7 @@ encoding=atascii
 
 [allocation]
 ; TODO
-zp_pointers=$80,$82,$84,$86,$88,$8a,$8c,$8e,$90,$92,$94,$96,$98,$9a,$9c,$9e,$a0,$a2,$a4
+zp_bytes=$80-$A5
 segment_default_start=$2000
 ; TODO
 segment_default_end=$3fff

include/apple2.ini

@@ -7,7 +7,7 @@ lenient_encoding=true
 
 [allocation]
 ; TODO
-zp_pointers=6,8,$EB,$ED,$FA,$FC
+zp_bytes=6-9, $EB-$EE, $FA-$FD
 segment_default_start=$0C00
 segment_default_end=$95FF
 

include/bbcmicro.ini

@@ -7,7 +7,7 @@ modules=bbc_kernal,bbc_hardware,default_panic,stdlib
 
 [allocation]
 ; TODO
-zp_pointers=$70, $72, $74, $76, $78, $7A, $7C, $7E, $80, $82, $84, $86, $88, $8A, $8C, $8E
+zp_bytes=$70-$8F
 ; $0E00 increases chances it will work on Electrons
 segment_default_start=$0E00
 ; The following is for Model B; for Model A, consider changing it to $31FF

include/c64_crt8k.ini

@@ -10,7 +10,7 @@ ro_arrays=true
 
 
 [allocation]
-zp_pointers=2-$ff
+zp_bytes=2-$ff
 segments=default,prgrom
 default_code_segment=prgrom
 segment_default_start=$800

include/lunix.ini

@@ -9,7 +9,7 @@ lunix=true
 
 
 [allocation]
-zp_pointers=$80-$bf
+zp_bytes=$80-$bf
 segments=default
 default_code_segment=default
 segment_default_start=$1006

include/nes_mmc4.ini

@@ -14,7 +14,7 @@ modules=nes_hardware,nes_routines,default_panic,nes_mmc4,stdlib
 ro_arrays=true
 
 [allocation]
-zp_pointers=all
+zp_bytes=all
 
 segments=default,ram,prgrom0,prgrom1,prgrom2,prgrom3,prgrom4,prgrom5,prgrom6,prgrom7,chrrom0,chrrom1
 default_code_segment=prgrom7

include/nes_small.ini

@@ -10,7 +10,7 @@ modules=nes_hardware,nes_routines,default_panic,stdlib
 ro_arrays=true
 
 [allocation]
-zp_pointers=all
+zp_bytes=all
 
 segments=default,prgrom,chrrom
 default_code_segment=prgrom

include/vcs.ini

@@ -10,7 +10,7 @@ zeropage_register=false
 
 
 [allocation]
-zp_pointers=$80,$82,$84,$86,$88,$8a,$8c,$8e,$90,$92,$94,$96,$98,$9a,$9c,$9e,$a0,$a2,$a4
+zp_bytes=$80-$a5
 segments=default,prgrom
 default_code_segment=prgrom
 

src/main/scala/millfork/Platform.scala

@@ -29,7 +29,7 @@ class Platform(
                 val codeAllocators: Map[String, UpwardByteAllocator],
                 val variableAllocators: Map[String, VariableAllocator],
                 val zpRegisterSize: Int,
-                val freeZpPointers: List[Int],
+                val freeZpBytes: List[Int],
                 val fileExtension: String,
                 val generateBbcMicroInfFile: Boolean,
                 val generateGameBoyChecksums: Boolean,
@@ -166,14 +166,29 @@ object Platform {
       bankDataStarts(b).foreach(dataStarts => if (dataStarts >= bankEnds(b)) log.error(s"Segment $b has invalid range"))
     })
 
-    val freePointers = as.get(classOf[String], "zp_pointers", "all") match {
-      case "all" => List.tabulate(128)(_ * 2)
-      case xs => xs.split("[, ]+").flatMap(parseNumberOrRange).toList
+    val freePointers: Option[List[Int]] = as.get(classOf[String], "zp_pointers", "") match {
+      case "all" => Some(List.tabulate(128)(_ * 2))
+      case "" => None
+      case xs => Some(xs.split("[, ]+").flatMap(s => parseNumberOrRange(s, 2)).toList)
+    }
+    val freeExplicitBytes: Option[List[Int]] = as.get(classOf[String], "zp_bytes", "") match {
+      case "all" => Some(List.tabulate(256)(identity))
+      case "" => None
+      case xs => Some(xs.split("[, ]+").flatMap(s => parseNumberOrRange(s, 1)).toList)
+    }
+
+    val freeZpBytes: List[Int] = (freePointers, freeExplicitBytes) match {
+      case (Some(l), None) => l.flatMap(i => List(i, i+1))
+      case (None, Some(l)) => l
+      case (None, None) => List.tabulate(256)(identity)
+      case (Some(_), Some(l)) =>
+        log.error(s"Cannot define both zp_pointers and zp_bytes")
+        l
     }
 
     val codeAllocators = banks.map(b => b -> new UpwardByteAllocator(bankStarts(b), bankCodeEnds(b)))
     val variableAllocators = banks.map(b => b -> new VariableAllocator(
-      if (b == "default" && CpuFamily.forType(cpu) == CpuFamily.M6502) freePointers else Nil, bankDataStarts(b) match {
+      if (b == "default" && CpuFamily.forType(cpu) == CpuFamily.M6502) freeZpBytes else Nil, bankDataStarts(b) match {
         case None => new AfterCodeByteAllocator(bankEnds(b))
         case Some(start) => new UpwardByteAllocator(start, bankEnds(b))
       }))
@@ -232,7 +247,7 @@ object Platform {
       codeAllocators.toMap,
       variableAllocators.toMap,
       zpRegisterSize,
-      freePointers,
+      freeZpBytes,
       if (fileExtension == "" || fileExtension.startsWith(".")) fileExtension else "." + fileExtension,
       generateBbcMicroInfFile,
       generateGameBoyChecksums,
@@ -269,15 +284,15 @@ object Platform {
     )
   }
 
-  def parseNumberOrRange(s:String)(implicit log: Logger): Seq[Int] = {
+  def parseNumberOrRange(s:String, step: Int)(implicit log: Logger): Seq[Int] = {
     if (s.contains("-")) {
       val segments = s.split("-")
       if (segments.length != 2) {
         log.fatal(s"Invalid range: `$s`")
       }
-      Range(parseNumber(segments(0)), parseNumber(segments(1)), 2)
+      Range(parseNumber(segments(0).trim()), parseNumber(segments(1).trim()), step)
     } else {
-      Seq(parseNumber(s))
+      Seq(parseNumber(s.trim()))
     }
   }
 

src/main/scala/millfork/output/AbstractAssembler.scala

@@ -184,9 +184,8 @@ abstract class AbstractAssembler[T <: AbstractCode](private val program: Program
     val variableAllocators = platform.variableAllocators
     val zpOccupied = mem.banks("default").occupied
     (0 until 0x100).foreach(i => zpOccupied(i) = true)
-    platform.freeZpPointers.foreach { i =>
+    platform.freeZpBytes.foreach { i =>
       zpOccupied(i) = false
-      zpOccupied(i + 1) = false
     }
 
     val optimizations = unfilteredOptimizations.filter(_.requiredFlags.forall(options.flag))
@@ -430,9 +429,9 @@ abstract class AbstractAssembler[T <: AbstractCode](private val program: Program
     env.allocateVariables(None, mem, callGraph, variableAllocators, options, labelMap.put, 3, forZpOnly = false)
 
     val defaultBank = mem.banks("default").index
-    if (platform.freeZpPointers.nonEmpty) {
-      val zpUsageOffset = platform.freeZpPointers.min
-      val zeropageOccupation = zpOccupied.slice(zpUsageOffset, platform.freeZpPointers.max + 2)
+    if (platform.freeZpBytes.nonEmpty) {
+      val zpUsageOffset = platform.freeZpBytes.min
+      val zeropageOccupation = zpOccupied.slice(zpUsageOffset, platform.freeZpBytes.max + 1)
       labelMap += "__zeropage_usage" -> (defaultBank, zeropageOccupation.lastIndexOf(true) - zeropageOccupation.indexOf(true) + 1)
       labelMap += "__zeropage_first" -> (defaultBank, zpUsageOffset + (zeropageOccupation.indexOf(true) max 0))
       labelMap += "__zeropage_last" -> (defaultBank, zpUsageOffset + (zeropageOccupation.lastIndexOf(true) max 0))

src/main/scala/millfork/output/VariableAllocator.scala

@@ -68,14 +68,14 @@ class UpwardByteAllocator(val startAt: Int, val endBefore: Int) extends ByteAllo
   override def preferredOrder: Option[List[Int]] = None
 }
 
-class ZeropageAllocator(val freeZpPointers: List[Int]) extends ByteAllocator {
+class ZeropageAllocator(val freeZpBytes: List[Int]) extends ByteAllocator {
 
   def notifyAboutEndOfCode(org: Int): Unit = ()
-  override def preferredOrder: Option[List[Int]] = if (freeZpPointers.isEmpty) None else Some(freeZpPointers.flatMap(i => Seq(i,i+1)))
+  override def preferredOrder: Option[List[Int]] = if (freeZpBytes.isEmpty) None else Some(freeZpBytes)
 
-  override def startAt: Int = if (freeZpPointers.isEmpty) 2 else freeZpPointers.min
+  override def startAt: Int = if (freeZpBytes.isEmpty) 2 else freeZpBytes.min
 
-  override def endBefore: Int = if (freeZpPointers.isEmpty) 2 else freeZpPointers.max + 2
+  override def endBefore: Int = if (freeZpBytes.isEmpty) 2 else freeZpBytes.max + 1
 }
 
 class AfterCodeByteAllocator(val endBefore: Int) extends ByteAllocator {
@@ -85,9 +85,9 @@ class AfterCodeByteAllocator(val endBefore: Int) extends ByteAllocator {
   override def preferredOrder: Option[List[Int]] = None
 }
 
-class VariableAllocator(pointers: List[Int], private val bytes: ByteAllocator) {
+class VariableAllocator(zpBytes: List[Int], private val bytes: ByteAllocator) {
 
-  val zeropage: ByteAllocator = new ZeropageAllocator(pointers)
+  val zeropage: ByteAllocator = new ZeropageAllocator(zpBytes)
 
   private val variableMap = mutable.Map[Int, mutable.Map[Int, Set[VariableVertex]]]()
 

src/test/scala/millfork/test/emu/EmuPlatform.scala

@@ -8,7 +8,7 @@ import millfork.{Cpu, CpuFamily, OutputStyle, Platform, ViceDebugOutputFormat}
   * @author Karol Stasiak
   */
 object EmuPlatform {
-  private val pointers: List[Int] = (0 until 256 by 2).toList
+  private val pointers: List[Int] = (0 until 256).toList
 
   def get(cpu: Cpu.Value) = new Platform(
     cpu,