added several color fade functions to the palette module (cx16)

compiler/res/prog8lib/cx16/palette.p8

@@ -106,6 +106,90 @@ palette {
         }
     }
 
+    sub fade_step_multi(ubyte startindex, ubyte endindex, uword target_rgb) -> bool {
+        ; Perform one color fade step for multiple consecutive palette entries.
+        ;   startindex = palette index of first color to fade
+        ;   endindex = palette index of last color to fade
+        ;   target_rgb = $RGB color value to fade towards
+        ; Returns true if one or more colors were changed, false if no fade steps were done anymore.
+        ; So you usually keep calling this until it returns false.
+        bool changed = false
+        while startindex <= endindex {
+            if fade_step(startindex, target_rgb)
+                changed=true
+            startindex++
+            if_z
+                break
+        }
+        return changed
+    }
+
+    sub fade_step_colors(ubyte startindex, ubyte endindex, uword target_colors) -> bool {
+        ; Perform one color fade step for multiple consecutive palette entries, to different target colors.
+        ;   startindex = palette index of first color to fade
+        ;   endindex = palette index of last color to fade
+        ;   target_colors = address of uword $RGB array of colors to fade towards
+        ; Returns true if one or more colors were changed, false if no fade steps were done anymore.
+        ; So you usually keep calling this until it returns false.
+        bool changed = false
+        ubyte target_index = 0
+        while startindex <= endindex {
+            if fade_step(startindex, peekw(target_colors+target_index))
+                changed=true
+            target_index += 2
+            startindex++
+            if_z
+                break
+        }
+        return changed
+    }
+
+    sub fade_step(ubyte index, uword target_rgb) -> bool {
+        ; Perform one color fade step for a single palette entry.
+        ;   index = palette index of the color to fade
+        ;   target_rgb = $RGB color value to fade towards
+        ; Returns true if the color was changed, false if no fade step was done anymore.
+        ; So you usually keep calling this until it returns false.
+        uword color = palette.get_color(index)
+        cx16.r0L = msb(color)            ; r
+        cx16.r1L = lsb(color) >> 4       ; g
+        cx16.r2L = lsb(color) & 15       ; b
+        cx16.r0H = msb(target_rgb) & 15  ; r2
+        cx16.r1H = lsb(target_rgb) >> 4  ; g2
+        cx16.r2H = lsb(target_rgb) & 15  ; b2
+
+        ubyte changed
+
+        ; use cmp() + status bits branches, to avoid multiple compares that could be done just once
+        cmp(cx16.r0L, cx16.r0H)
+        if_ne {
+            if_cc
+                cx16.r0L++
+            else
+                cx16.r0L--
+            changed++
+        }
+        cmp(cx16.r1L, cx16.r1H)
+        if_ne {
+            if_cc
+                cx16.r1L++
+            else
+                cx16.r1L--
+            changed++
+        }
+        cmp(cx16.r2L, cx16.r2H)
+        if_ne {
+            if_cc
+                cx16.r2L++
+            else
+                cx16.r2L--
+            changed++
+        }
+
+        palette.set_color(index, mkword(cx16.r0L, cx16.r1L<<4 | cx16.r2L))
+        return changed!=0
+    }
+
     sub set_c64pepto() {
         ; set first 16 colors to the "Pepto" PAL commodore-64 palette  http://www.pepto.de/projects/colorvic/
         uword[] colors = [

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

@@ -1008,6 +1008,11 @@ internal class AstChecker(private val program: Program,
                 errors.err("array literal for iteration must contain constants. Try using a separate array variable instead?", array.position)
         }
 
+        if(array.parent is Assignment) {
+            val assignTarget = (array.parent as Assignment).target
+            if(!assignTarget.inferType(program).isArray)
+                errors.err("cannot assign array to a non-array variable", assignTarget.position)
+        }
         super.visit(array)
     }
 

docs/source/todo.rst

@@ -1,8 +1,6 @@
 TODO
 ====
 
-Put palette fade to white / black in.
-
 Regenerate skeleton doc files.
 
 Improve register load order in subroutine call args assignments:

examples/test.p8

@@ -1,30 +1,37 @@
+%import palette
 %import textio
-%import string
-%zeropage basicsafe
+%option no_sysinit
 
 main {
     sub start() {
-        str name1 = "irmen"
-        str name2 = "other"
-        bool[2] flags = [true, false]
+        repeat 4 {
+            for cx16.r0L in 0 to 15 {
+                txt.color2(cx16.r0L, cx16.r0L)
+                txt.spc()
+                txt.spc()
+                txt.spc()
+                txt.spc()
+            }
+            txt.nl()
+        }
+        bool changed
+        uword[] colors = [
+            $f00, $800, $200, $000,
+            $f0f, $80f, $20f, $00f
+        ]
+        do {
+            sys.waitvsync()
+            sys.waitvsync()
+            changed = palette.fade_step_colors(0, 8, colors)
+        } until not changed
 
-        txt.print(name1)
-        txt.nl()
-        name1 = name2
-        txt.print(name1)
-        txt.nl()
-        flags = [false, true]
-
-        ubyte[10] array
-        ubyte[10] array2
-
-        void string.copy(name2, name1)
-        array = array2
-        name2 = "zzz"
-        array = [1,2,3,4,5,6,7,8,9,10]
-        ;; array = cx16.r0
-        ;; array = name1
-        ;; name1 = array
-        ;; name1 = cx16.r0
+        sys.wait(60)
+        changed = false
+        do {
+            sys.waitvsync()
+            sys.waitvsync()
+            changed = palette.fade_step_multi(0, 8, $fff)
+        } until not changed
+        sys.wait(60)
     }
 }