Allow setting the size of the zeropage register from the command line.

docs/api/command-line.md

@@ -81,10 +81,11 @@ Default: native if targeting 65816, no otherwise.
 `.ini` equivalent: `prevent_jmp_indirect_bug`.
 Default: no if targeting a 65C02-compatible architecture or a non-6502 architecture, yes otherwise.
 
-* `-fzp-register`, `-fno-zp-register` – Whether should reserve 4 bytes of zero page as a pseudoregister.
-Increases language features. 
+* `-fzp-register=[0-15]`, `-fno-zp-register` – Sets the size of the zeropage pseudoregister.
+Increases language features on 6502-based targets.
+Recommended values: 2 or 4. Values higher than 4 are pointless.  
 `.ini` equivalent: `zeropage_register`.
-Default: yes if targeting a 6502-based architecture, no otherwise.
+Default: 4 if targeting a 6502-based architecture, 0 otherwise.
                     
 * `-fdecimal-mode`, `-fno-decimal-mode` –
 Whether hardware decimal mode should be used (6502 only).

src/main/scala/millfork/Main.scala

@@ -323,7 +323,7 @@ object Main {
     }.description("Whether should emit 65CE02 opcodes.")
     boolean("-fhuc6280-ops", "-fno-huc6280-ops").action { (c, v) =>
       c.changeFlag(CompilationFlag.EmitHudsonOpcodes, v)
-    }.description("Whether should emit HuC6280huc6280 opcodes.")
+    }.description("Whether should emit HuC6280 opcodes.")
     flag("-fno-65816-ops").action { c =>
       c.changeFlag(CompilationFlag.EmitEmulation65816Opcodes, b = false)
       c.changeFlag(CompilationFlag.EmitNative65816Opcodes, b = false)
@@ -344,12 +344,19 @@ object Main {
     boolean("-fillegals", "-fno-illegals").action { (c, v) =>
       c.changeFlag(CompilationFlag.EmitIllegals, v)
     }.description("Whether should emit illegal (undocumented) NMOS opcodes. Requires -O2 or higher to have an effect.")
-    boolean("-fzp-register", "-fno-zp-register").action { (c, v) =>
-      c.copy(zpRegisterSize = Some(if (v) 2 else 0)) // TODO
-    }.description("Whether should use 2 bytes of zeropage as a pseudoregister.")
+    flag("-fzp-register=[0-15]").description("Set the size of the zeropage pseudoregister (6502 only).").dummy()
+    (0 to 15).foreach(i =>
+      flag("-fzp-register="+i).action(c => c.copy(zpRegisterSize = Some(i))).hidden()
+    )
+    flag("-fzp-register").action { c =>
+      c.copy(zpRegisterSize = Some(4))
+    }.description("Alias for -fzp-register=4.")
+    flag("-fno-zp-register").action { c =>
+      c.copy(zpRegisterSize = Some(0))
+    }.description("Alias for -fzp-register=0.")
     boolean("-fjmp-fix", "-fno-jmp-fix").action { (c, v) =>
       c.changeFlag(CompilationFlag.PreventJmpIndirectBug, v)
-    }.description("Whether should prevent indirect JMP bug on page boundary.")
+    }.description("Whether should prevent indirect JMP bug on page boundary (6502 only).")
     boolean("-fdecimal-mode", "-fno-decimal-mode").action { (c, v) =>
       c.changeFlag(CompilationFlag.DecimalMode, v)
     }.description("Whether hardware decimal mode should be used (6502 only).")

src/main/scala/millfork/cli/CliOption.scala

@@ -25,6 +25,7 @@ trait CliOption[T, O <: CliOption[T, O]] {
   private[cli] val _shortName: String
   private[cli] var _description: String = ""
   private[cli] var _hidden = false
+  private[cli] var _dummy = false
   private[cli] var _maxEncounters = 1
   private[cli] var _minEncounters = 0
   private[cli] var _actualEncounters = 0
@@ -71,6 +72,11 @@ trait CliOption[T, O <: CliOption[T, O]] {
     this
   }
 
+  def dummy(): O = {
+    _dummy = true
+    this
+  }
+
   def minCount(count: Int): O = {
     _minEncounters = count
     this

src/main/scala/millfork/cli/CliParser.scala

@@ -41,16 +41,16 @@ class CliParser[T] {
     args match {
       case k :: v :: xs if mapOptions.contains(k) =>
         mapOptions(k) match {
-          case p: ParamOption[T] => parseInner(p.encounter(v, context), xs)
+          case p: ParamOption[T] if !p._dummy => parseInner(p.encounter(v, context), xs)
           case _ => ???
         }
       case k :: xs if mapFlags.contains(k) =>
         mapFlags(k) match {
-          case p: FlagOption[T] =>
+          case p: FlagOption[T] if !p._dummy =>
             parseInner(p.encounter(context), xs)
-          case p: BooleanOption[T] =>
+          case p: BooleanOption[T] if !p._dummy =>
             parseInner(p.encounter(k, context), xs)
-          case p: NoMoreOptions[T] =>
+          case p: NoMoreOptions[T] if !p._dummy =>
             p.encounter()
             xs.foldLeft(context)((t, x) => _default.encounter(x, t))
           case _ => ???