From b9472afb31266342b280f330b3d932d26cd7375b Mon Sep 17 00:00:00 2001
From: Sven Van de Velde <sven.van.de.velde@telenet.be>
Date: Wed, 13 Dec 2023 17:16:06 +0100
Subject: [PATCH] - zeropages allocated for local variables, used in procedures
 exported to .Asm libraries, are also added as part of the function prototype
 using the directive __zp_reserve.

---
 .../dk/camelot64/kickc/asm/AsmLibrary.java    | 67 +++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/src/main/java/dk/camelot64/kickc/asm/AsmLibrary.java b/src/main/java/dk/camelot64/kickc/asm/AsmLibrary.java
index e9c72465e..750105fee 100644
--- a/src/main/java/dk/camelot64/kickc/asm/AsmLibrary.java
+++ b/src/main/java/dk/camelot64/kickc/asm/AsmLibrary.java
@@ -4,6 +4,7 @@ import dk.camelot64.kickc.model.Program;
 import dk.camelot64.kickc.model.Registers;
 import dk.camelot64.kickc.model.symbols.Procedure;
 import dk.camelot64.kickc.model.symbols.Scope;
+import dk.camelot64.kickc.model.symbols.Symbol;
 import dk.camelot64.kickc.model.symbols.Variable;
 import dk.camelot64.kickc.model.values.ProcedureRef;
 
@@ -56,6 +57,39 @@ public class AsmLibrary extends AsmLine {
       return procedures.containsKey(procedureName);
    }
 
+
+   /**
+    * Generate the zeropages used
+    *
+    * @param param     The variable to investigate
+    * @param scope     The scope (procedure)
+    * @param zp        The zero pages to append
+    */
+   void generateZPVar(Variable param, Scope scope, StringBuilder zp) {
+      if (param == null) return;
+      if (param.isKindPhiMaster()) {
+         List<Variable> versions = new ArrayList<>(scope.getVersions(param));
+         if (versions.size() > 0) if (param.getLocalName().equals("return")) {
+            // Choose the last version for return values
+            param = versions.get(versions.size() - 1);
+         } else {
+            // Choose the first version for parameters
+            param = versions.get(0);
+         }
+         else
+            // Parameter optimized away to a constant or unused
+            return;
+      }
+
+      Registers.Register allocation = param.getAllocation();
+      if (allocation instanceof Registers.RegisterZpMem registerZp) {
+         if(!zp.isEmpty()) zp.append(", ");
+         zp.append(AsmFormat.getAsmNumber(registerZp.getZp()));
+      }
+
+      return;
+   }
+
    /**
     * Generate part of a comment that describes a returnvalue/parameter
     *
@@ -99,11 +133,34 @@ public class AsmLibrary extends AsmLine {
       return param;
    }
 
+   /**
+    * Generate a header for a C function prototype for .asm library import.
+    * It defines the signature of each procedure in terms of the registers used,
+    * which can be __mem, __zp, __register for the procedure parameters and return value.
+    * Local variables, when allocated to __zp within the pre-compiled .asm library,
+    * are reserved using __zp_reserve directive.
+    * @param procedure The procedure to generate the header for.
+    * @return A String with the generated function prototype.
+    */
    private String generateHeader(Procedure procedure) {
       StringBuilder signature = new StringBuilder();
       signature.append("extern ");
       signature.append(procedure.getCallingConvention().getName()).append(" ");
       signature.append("__asm_import(\"").append(this.getName()).append("\") ");
+
+      // reserve used zero pages if any.
+      StringBuilder zp = new StringBuilder();
+      for(Symbol symbol : procedure.getSymbols().values()) {
+         if(symbol instanceof Variable variable) {
+            generateZPVar(variable, procedure, zp);
+         }
+      }
+      if(!zp.isEmpty()) {
+         zp.insert(0, "__zp_reserve(");
+         zp.append(") ");
+      }
+      signature.append(zp);
+
       generateSignatureVar(procedure.getLocalVar("return"), procedure, signature);
       signature.append(procedure.getReturnType().toCDecl());
       signature.append(" ").append(procedure.getLocalName()).append("(");
@@ -119,6 +176,16 @@ public class AsmLibrary extends AsmLine {
       return signature.toString();
    }
 
+   /**
+    * Generate a header file for an .asm library import.
+    * This is to be used by the main program to import an .asm library.
+    * It defines the signature of each procedure in terms of the registers used,
+    * which can be __mem, __zp, __register for the procedure parameters and return value.
+    * Local variables, when allocated to __zp within the pre-compiled .asm library,
+    * are reserved using __zp_reserve directive.
+    * @param program The program
+    * @return A string with the generated function prototypes for import.
+    */
    public String generateHeaders(Program program) {
       StringBuilder headers = new StringBuilder();
       for(String procedureName: this.getProcedures()) {