fix gfx2 screen fill broken when using verafx

compiler/res/prog8lib/cx16/gfx2.p8

@@ -32,6 +32,7 @@ gfx2 {
     bool monochrome_dont_stipple_flag = false            ; set to false to enable stippling mode in monochrome displaymodes
 
     sub screen_mode(ubyte mode) {
+        cx16.VERA_CTRL=0
         when mode {
             1 -> {
                 ; lores monochrome

compiler/res/prog8lib/cx16/verafx.p8

@@ -6,6 +6,17 @@
 verafx {
     %option no_symbol_prefixing
 
+    sub fill(ubyte vbank, uword vaddr, ubyte data, uword numlongs) {
+        ; TODO use vera fx cache write
+        cx16.vaddr(vbank, vaddr, 0, true)
+        repeat numlongs {
+            cx16.VERA_DATA0 = data
+            cx16.VERA_DATA0 = data
+            cx16.VERA_DATA0 = data
+            cx16.VERA_DATA0 = data
+        }
+    }
+
     ; unsigned multiplication just passes the values as signed to muls
     ; if you do this yourself in your call to muls, it will save a few instructions.
     sub mult(uword value1, uword value2) -> uword {
@@ -46,9 +57,10 @@ verafx {
             stz  cx16.VERA_DATA0      ; multiply and write out result
             lda  #%00010001           ; $01 with Increment 1
             sta  cx16.VERA_ADDR_H     ; so we can read out the result
-            stz  cx16.VERA_FX_CTRL    ; Cache write disable
             lda  cx16.VERA_DATA0
             ldy  cx16.VERA_DATA0
+            stz  cx16.VERA_FX_CTRL    ; Cache write disable
+            stz  cx16.VERA_CTRL       ; reset DCSEL
             rts
 ; we skip the upper 16 bits of the result:
 ;            lda  cx16.VERA_DATA0

docs/source/todo.rst

@@ -1,7 +1,6 @@
 TODO
 ====
 
-- add a compiler switch to replace all calls to the math word mul routine on the X16 by the verafx call instead. Search TODO("vera fx mul")
 - [on branch: shortcircuit] investigate McCarthy evaluation again? this may also reduce code size perhaps for things like if a>4 or a<2 ....
 - [on branch: ir-less-branch-opcodes] IR: reduce the number of branch instructions such as BEQ, BEQR, etc (gradually), replace with CMP(I) + status branch instruction
 - IR: reduce amount of CMP/CMPI after instructions that set the status bits correctly (LOADs? INC? etc), but only after setting the status bits is verified!
@@ -20,6 +19,7 @@ Future Things and Ideas
 ^^^^^^^^^^^^^^^^^^^^^^^
 Compiler:
 
+- Currently "320*240/8/8" gives integer overflow, so: allow constant integer subexpressions to contain out of range integers (>65535 etc) as long as the final constant value is within byte/word range.
 - allow 'chained' array indexing for expressions:  value = ptrarray[0][0]
 - allow 'chained' array indexing for assign targets:  ptrarray[0][0] = 42   this is just evaluating the lhs as a uword pointer expression
 

examples/test.p8

@@ -1,7 +1,7 @@
-%import diskio
+%import gfx2
 %import textio
 ;%import math
-;%import verafx
+%import verafx
 %zeropage basicsafe
 %option no_sysinit
 
@@ -36,6 +36,11 @@ main {
         txt.print_w(w1)
         txt.nl()
 
+        gfx2.screen_mode(1)
+        verafx.fill(0, 0, %10101010, 1200)        ; should fill top half of the screen
+        verafx.fill(0, 4800, %11111111, 1200)     ; should fill bottom half of the screen
+
+
 ;        txt.print_uw(math.mul16_last_upper())
 ;        txt.nl()
 ;        uword value1=5678