don't require carry parameter Pc to asmsubs to be last

compiler/src/prog8/compiler/astprocessing/AstChecker.kt

@@ -351,10 +351,6 @@ internal class AstChecker(private val program: Program,
             if(statusFlagsNoCarry.isNotEmpty())
                 err("can only use Carry as status flag parameter")
 
-            val carryParameter = subroutine.asmParameterRegisters.singleOrNull { it.statusflag==Statusflag.Pc }
-            if(carryParameter!=null && carryParameter !== subroutine.asmParameterRegisters.last())
-                err("carry parameter has to come last")
-
         } else {
             // Pass-by-reference datatypes can not occur as parameters to a subroutine directly
             // Instead, their reference (address) should be passed (as an UWORD).

compiler/src/prog8/compiler/target/c64/codegen/FunctionCallAsmGen.kt

@@ -91,11 +91,15 @@ internal class FunctionCallAsmGen(private val program: Program, private val asmg
                     when {
                         stmt.args.all {isNoClobberRisk(it)} -> {
                             // There's no risk of clobbering for these simple argument types. Optimize the register loading directly from these values.
+                            // register assignment order: 1) cx16 virtual word registers, 2) actual CPU registers, 3) CPU Carry status flag.
                             val argsInfo = sub.parameters.withIndex().zip(stmt.args).zip(sub.asmParameterRegisters)
-                            val (cx16virtualRegsArgsInfo, otherRegsArgsInfo) = argsInfo.partition { it.second.registerOrPair in Cx16VirtualRegisters }
-                            for(arg in cx16virtualRegsArgsInfo)
+                            val (cx16virtualRegs, args2) = argsInfo.partition { it.second.registerOrPair in Cx16VirtualRegisters }
+                            val (cpuRegs, statusRegs) = args2.partition { it.second.registerOrPair!=null }
+                            for(arg in cx16virtualRegs)
                                 argumentViaRegister(sub, arg.first.first, arg.first.second)
-                            for(arg in otherRegsArgsInfo)
+                            for(arg in cpuRegs)
+                                argumentViaRegister(sub, arg.first.first, arg.first.second)
+                            for(arg in statusRegs)
                                 argumentViaRegister(sub, arg.first.first, arg.first.second)
                         }
                         else -> {

docs/source/todo.rst

@@ -2,9 +2,10 @@
 TODO
 ====
 
-- don't require carry parameter Pc to asmsubs to be last; sort this out yourself like with the R0-R15 registers
 - make blocks without explicit memory address, word-aligned in the assembly.
+
 - add sound to the cx16 tehtriz
+
 - hoist all variable declarations up to the subroutine scope *before* even the constant folding takes place (to avoid undefined symbol errors when referring to a variable from another nested scope in the subroutine)
 - refactor the asmgen into their own submodule?
 - refactor the compiler optimizers into their own submodule?

examples/cx16/vtui/testvtui.p8

@@ -40,6 +40,6 @@ vtui $1000 {
     romsub $1023  =  pet2scr(ubyte char @A) -> ubyte @A
     romsub $1026  =  scr2pet(ubyte char @A) -> ubyte @A
     romsub $1029  =  border(ubyte mode @A, ubyte width @R1, ubyte height @R2, ubyte colors @X) clobbers(Y)       ; NOTE: mode 6 means 'custom' characters taken from r3 - r6
-    romsub $102c  =  save_rect(ubyte vbank @A, uword address @R0, ubyte width @R1, ubyte height @R2, ubyte ramtype @Pc) clobbers(A, X, Y)
-    romsub $102f  =  rest_rect(ubyte vbank @A, uword address @R0, ubyte width @R1, ubyte height @R2, ubyte ramtype @Pc) clobbers(A, X, Y)
+    romsub $102c  =  save_rect(ubyte ramtype @Pc, ubyte vbank @A, uword address @R0, ubyte width @R1, ubyte height @R2) clobbers(A, X, Y)
+    romsub $102f  =  rest_rect(ubyte ramtype @Pc, ubyte vbank @A, uword address @R0, ubyte width @R1, ubyte height @R2) clobbers(A, X, Y)
 }

examples/test.p8

@@ -5,8 +5,20 @@
 main {
 
     sub start() {
+        ubyte rr = bla(1,true,2)
+        txt.print_ub(rr)
+        txt.nl()
+        rr = bla(1,false,2)
+        txt.print_ub(rr)
+    }
 
-        uword zzz=memory("derp", 2000)
-        txt.print("hello")
+    asmsub bla(ubyte aa @A, ubyte cc @Pc, ubyte bb @Y) -> ubyte @A{
+        %asm {{
+            bcc  +
+            lda  #10
+            bne  end
++           lda  #20
+end         rts
+        }}
     }
 }