we don't implement asmsub params via @stack yet

compiler/src/prog8/ast/AstToSourceCode.kt

@@ -140,7 +140,7 @@ class AstToSourceCode(val output: (text: String) -> Unit, val program: Program):
                             param.second.stack -> "stack"
                             param.second.registerOrPair!=null -> param.second.registerOrPair.toString()
                             param.second.statusflag!=null -> param.second.statusflag.toString()
-                            else -> "?????1"
+                            else -> "?????"
                         }
                 output("${datatypeString(param.first.type)} ${param.first.name} @$reg")
                 if(param.first!==subroutine.parameters.last())

compiler/src/prog8/ast/antlr/Antr2Kotlin.kt

@@ -254,7 +254,7 @@ private fun prog8Parser.Asmsub_declContext.toAst(): AsmsubDecl {
     val clobbers = asmsub_clobbers()?.clobber()?.toAst() ?: emptySet()
     val normalParameters = params.map { SubroutineParameter(it.name, it.type, it.position) }
     val normalReturntypes = returns.map { it.type }
-    val paramRegisters = params.map { RegisterOrStatusflag(it.registerOrPair, it.statusflag, it.stack) }
+    val paramRegisters = params.map { RegisterOrStatusflag(it.registerOrPair, it.statusflag, false) }
     val returnRegisters = returns.map { RegisterOrStatusflag(it.registerOrPair, it.statusflag, it.stack) }
     return AsmsubDecl(name, normalParameters, normalReturntypes, paramRegisters, returnRegisters, clobbers)
 }
@@ -263,7 +263,7 @@ private class AsmSubroutineParameter(name: String,
                                      type: DataType,
                                      val registerOrPair: RegisterOrPair?,
                                      val statusflag: Statusflag?,
-                                     val stack: Boolean,
+                                     // TODO implement: val stack: Boolean,
                                      position: Position) : SubroutineParameter(name, type, position)
 
 private class AsmSubroutineReturn(val type: DataType,
@@ -305,8 +305,7 @@ private fun prog8Parser.Asmsub_paramsContext.toAst(): List<AsmSubroutineParamete
             else -> throw FatalAstException("invalid register or status flag '$name'")
         }
     }
-    AsmSubroutineParameter(vardecl.varname.text, datatype, registerorpair, statusregister,
-            !it.stack?.text.isNullOrEmpty(), toPosition())
+    AsmSubroutineParameter(vardecl.varname.text, datatype, registerorpair, statusregister, toPosition())
 }
 
 private fun prog8Parser.Functioncall_stmtContext.toAst(): Statement {

docs/source/syntaxreference.rst

@@ -514,18 +514,20 @@ and returning stuff in several registers as well. The ``clobbers`` clause is use
 what CPU registers are clobbered by the call instead of being unchanged or returning a meaningful result value.
 
 
-Subroutines that are implemented purely in assembly code and which have an assembly calling convention (i.e.
-the parameters are strictly passed via cpu registers), are defined like this::
+User subroutines in the program source code that are implemented purely in assembly and which have an assembly calling convention (i.e.
+the parameters are strictly passed via cpu registers), are defined with ``asmsub`` like this::
 
-    asmsub  FREADS32() clobbers(A,X,Y)  {
+    asmsub  clear_screenchars (ubyte char @ A) clobbers(Y)  {
         %asm {{
-            lda  $62
-            eor  #$ff
-            asl  a
-            lda  #0
-            ldx  #$a0
-            jmp  $bc4f
-        }}
+            ldy  #0
+    _loop   sta  c64.Screen,y
+            sta  c64.Screen+$0100,y
+            sta  c64.Screen+$0200,y
+            sta  c64.Screen+$02e8,y
+            iny
+            bne  _loop
+            rts
+            }}
     }
 
 the statement body of such a subroutine should consist of just an inline assembly block.

docs/source/todo.rst

@@ -5,6 +5,7 @@ TODO
 - further optimize assignment codegeneration
 - auto select correct library to import based on target, instead of having c64- and  cx16-  prefix variants
 - get rid of all TODO's ;-)
+- implement @stack for asmsub parameters
 - make it possible to use cpu opcodes such as 'nop' as variable names by prefixing all asm vars with something such as '_'
 - option to load the built-in library files from a directory instead of the embedded ones (for easier library development/debugging)
 - aliases for imported symbols for example perhaps '%alias print = c64scr.print' ?

parser/antlr/prog8.g4

@@ -273,7 +273,7 @@ asmsub_decl : identifier '(' asmsub_params? ')' asmsub_clobbers? asmsub_returns?
 
 asmsub_params :  asmsub_param (',' EOL? asmsub_param)* ;
 
-asmsub_param :  vardecl '@' (identifier | stack='stack') ;      // A,X,Y,AX,AY,XY,Pc,Pz,Pn,Pv allowed
+asmsub_param :  vardecl '@' identifier ;      // A,X,Y,AX,AY,XY,Pc,Pz,Pn,Pv allowed.  TODO implement  stack='stack'
 
 asmsub_clobbers : 'clobbers' '(' clobber? ')' ;