cx16: added routines to get and set the default palette (new rom 49+ extapi)

compiler/res/prog8lib/cx16/palette.p8

@@ -257,6 +257,7 @@ palette {
 
     sub set_default16() {
         ; set first 16 colors to the defaults on the X16
+        ; (doesn't use the rom table so this works on roms older than 49 as well)
         uword[] @nosplit colors = [
             $000,   ; 0 = black
             $fff,   ; 1 = white
@@ -277,4 +278,12 @@ palette {
         ]
         set_rgb_nosplit(colors, len(colors), 0)
     }
+
+    ; set the full 256 colors in the palette back to its default values on the X16
+    ; NOTE: this routine requires rom version 49+
+    alias set_default = cx16.set_default_palette
+
+    ; get the bank and address of the word-array containing the 256 default palette colors
+    ; NOTE: this routine requires rom version 49+
+    alias get_default = cx16.get_default_palette
 }

compiler/res/prog8lib/cx16/syslib.p8

@@ -670,12 +670,33 @@ asmsub scnsiz(ubyte width @X, ubyte heigth @Y) clobbers(A,X,Y) {
 }
 
 asmsub memory_decompress_from_func(uword datafunction @R4, uword output @R1)  clobbers(A,X,Y) -> uword @R1  {
+    ; requires rom v49+
     %asm {{
         lda  #EXTAPI_memory_decompress_from_func
         jmp  cx16.extapi
     }}
 }
 
+asmsub get_default_palette() -> ubyte @A, uword @XY {
+    ; returns memory address of default palette; bank in A and address in XY
+    ; requires rom v49+
+    %asm {{
+        sec
+        lda  #EXTAPI_default_palette
+        jmp  cx16.extapi
+    }}
+}
+
+asmsub set_default_palette() {
+    ; sets default palette in to the Vera
+    ; requires rom v49+
+    %asm {{
+        clc
+        lda  #EXTAPI_default_palette
+        jmp  cx16.extapi
+    }}
+}
+
 asmsub get_charset() -> ubyte @A {
     ;Get charset mode.  result: 0=unknown, 1=ISO, 2=PETSCII upper case/gfx, 3=PETSCII lowercase.
     %asm {{

docs/source/todo.rst

@@ -1,6 +1,8 @@
 TODO
 ====
 
+symboldump doesn't include aliased symbols (like palette.set_default)
+
 atari customtarget: default output should be .xex not .prg (10.5 still did it correctly)
 
 test irqs on various targets: set_irq, set_rasterirq