cx16.set_screen_mode() no longer returns anything.

tweak when codegen slightly.
allow trailing comma in array literals.

set_screen_mode failure status is really uncommon and still returned by the real kernal routine screen_mode().

codeGenCpu6502/src/prog8/codegen/cpu6502/AsmGen.kt

@@ -929,7 +929,7 @@ $repeatLabel""")
     }
 
     private fun translate(stmt: PtWhen) {
-        val endLabel = makeLabel("choice_end")
+        val endLabel = makeLabel("when_end")
         val choiceBlocks = mutableListOf<Pair<String, PtNodeGroup>>()
         val conditionDt = stmt.value.type
         if(conditionDt.isByte)
@@ -939,23 +939,28 @@ $repeatLabel""")
 
         for(choiceNode in stmt.choices.children) {
             val choice = choiceNode as PtWhenChoice
-            val choiceLabel = makeLabel("choice")
+            var choiceLabel = makeLabel("choice")
             if(choice.isElse) {
                 translate(choice.statements)
             } else {
-                choiceBlocks.add(choiceLabel to choice.statements)
+                if(choice.statements.children.isEmpty()) {
+                    // no statements for this choice value, jump to the end immediately
+                    choiceLabel = endLabel
+                } else {
+                    choiceBlocks.add(choiceLabel to choice.statements)
+                }
                 for (cv in choice.values.children) {
                     val value = (cv as PtNumber).number.toInt()
                     if(conditionDt.isByte) {
                         out("  cmp  #${value.toHex()} |  beq  $choiceLabel")
                     } else {
                         out("""
-                            cmp  #<${value.toHex()}
-                            bne  +
-                            cpy  #>${value.toHex()}
-                            beq  $choiceLabel
+                        cmp  #<${value.toHex()}
+                        bne  +
+                        cpy  #>${value.toHex()}
+                        beq  $choiceLabel
 +
-                            """)
+                        """)
                     }
                 }
             }
@@ -964,7 +969,7 @@ $repeatLabel""")
         for(choiceBlock in choiceBlocks.withIndex()) {
             out(choiceBlock.value.first)
             translate(choiceBlock.value.second)
-            if(choiceBlock.index<choiceBlocks.size-1)
+            if (choiceBlock.index < choiceBlocks.size - 1)
                 jmp(endLabel)
         }
         out(endLabel)

compiler/res/prog8lib/cx16/syslib.p8

@@ -565,8 +565,8 @@ const ubyte  EXTAPI16_stack_enter_kernal_stack = $03
 const ubyte  EXTAPI16_stack_leave_kernal_stack = $04
 
 
-asmsub set_screen_mode(ubyte mode @A) clobbers(A,X,Y) -> bool @Pc {
-    ; -- convenience wrapper for screen_mode() to just set a new mode (and return success)
+asmsub set_screen_mode(ubyte mode @A) clobbers(A,X,Y) {
+    ; -- convenience wrapper for screen_mode() to just set a new mode and ignore any return values
     %asm {{
         clc
         jmp  screen_mode

docs/source/comparing.rst

@@ -21,6 +21,7 @@ The language
 - Ternary operator ``x ? value1 : value2`` is available in the form of an *if-expression*: ``if x  value1 else value2``
 - There's a Swift/Zig/Go style ``defer`` statement for delayed cleanup is available in the subroutine scope.
 - Qualified names are searched from within the top level namespace (so you have to provide the full qualified name). Unqualified names are locally scoped.
+- A trailing comma is allowed optionally in array literals:  [1,2,3,]  is a valid array of values 1, 2 and 3.
 
 
 No linker

docs/source/variables.rst

@@ -264,7 +264,8 @@ Arrays
 ^^^^^^
 Arrays can be created from a list of booleans, bytes, words, floats, or addresses of other variables
 (such as explicit address-of expressions, strings, or other array variables) - values in an array literal
-always have to be constants. Here are some examples of arrays::
+always have to be constants. A trailing comma is allowed, sometimes this is easier when copying values
+or when adding more stuff to the array later. Here are some examples of arrays::
 
     byte[10]  array                   ; array of 10 bytes, initially set to 0
     byte[]  array = [1, 2, 3, 4]      ; initialize the array, size taken from value

examples/cx16/interpolation.p8

@@ -15,7 +15,7 @@ main {
     uword mx, my
 
     sub start() {
-        void cx16.set_screen_mode(3)
+        cx16.set_screen_mode(3)
         cx16.mouse_config2(1)
         sprites.set_mousepointer_hand()
 

examples/test.p8

@@ -1,8 +1,22 @@
+%import textio
+%zeropage basicsafe
+%option no_sysinit
+
 main {
     sub start() {
-        cx16.r0 = $aabb
-        cx16.r1 = $1122
-
-        goto cx16.r1+256
+        ubyte[] array = [
+            11,
+            22,
+            33,
+            44,
+        ]
+        for cx16.r0L in [1,2,3,4,] {
+            txt.print_ub(cx16.r0L)
+            txt.nl()
+        }
+        for cx16.r0L in array {
+            txt.print_ub(cx16.r0L)
+            txt.nl()
+        }
     }
 }

parser/src/main/antlr/Prog8ANTLR.g4

@@ -256,7 +256,7 @@ integerliteral :  intpart=(DEC_INTEGER | HEX_INTEGER | BIN_INTEGER) ;
 
 booleanliteral :  'true' | 'false' ;
 
-arrayliteral :  '[' EOL? expression (',' EOL? expression)* EOL? ']' ;       // you can split the values over several lines
+arrayliteral :  '[' EOL? expression (',' EOL? expression)* ','? EOL? ']' ;       // you can split the values over several lines, trailing comma allowed
 
 stringliteral : (encoding=NAME ':')? STRING ;