c64: added a couple of routines that calculate the correct memory loc…

…ations for video ram and sprite pointers etc. based on current VIC-II memory setup.

the examples with sprites, now use it.

compiler/res/prog8lib/c64/graphics.p8

@@ -10,15 +10,16 @@ graphics {
     const uword WIDTH = 320
     const ubyte HEIGHT = 200
 
-    const uword BITMAP_ADDRESS = $6000      ; MUST BE IN REGULAR RAM if you are not messing with ROM/RAM banking.
-    const uword CHARS_ADDRESS = $5c00       ; must be in same vic bank as the bitmap
+    const uword BITMAP_ADDRESS = $6000      ; MUST BE IN REGULAR RAM if you are not messing with ROM/RAM banking. (and $2000-aligned)
+                                            ; note: this constant is also used in a asm multiplication table below!
+    const uword CHARS_ADDRESS = $5c00       ; must be in same vic memory bank as the bitmap.
 
     sub enable_bitmap_mode() {
         ; enable bitmap screen, erase it and set colors to black/white.
         clear_screen(1, 0)
         c64.SCROLY = %00111011      ; enable bitmap graphics mode
         c64.SCROLX = %00001000      ; 40 column mode, no scrolling, multicolor bitmap off
-        c64.VMCSB = (lsb(CHARS_ADDRESS >> 6) & $F0) | (((BITMAP_ADDRESS & $3fff) / $0800) << 1)     ; set bitmap address
+        c64.VMCSB = (lsb(CHARS_ADDRESS >> 6) & $F0) | (lsb((BITMAP_ADDRESS & $3fff) / $0800) << 1)     ; set bitmap address
         c64.CIA2DDRA |= %11
         c64.CIA2PRA = lsb(BITMAP_ADDRESS >> 14) ^ 3     ; set VIC bank.
     }

compiler/res/prog8lib/c64/syslib.p8

@@ -136,7 +136,8 @@ c64 {
     %option no_symbol_prefixing
 
         ; the default locations of the 8 sprite pointers (store address of sprite / 64)
-        ; (depending on the VIC bank and screen ram address selection these can be shifted around though)
+        ; (depending on the VIC bank and screen ram address selection these can be shifted around though,
+        ; see the two routines after this for a dynamic way of determining the correct memory location)
         &ubyte  SPRPTR0         = 2040
         &ubyte  SPRPTR1         = 2041
         &ubyte  SPRPTR2         = 2042
@@ -285,6 +286,39 @@ c64 {
 
 ; ---- end of SID registers ----
 
+
+    sub get_vic_memory_base() -> uword {
+        ; one of the 4 possible banks. $0000/$4000/$8000/$c000.
+        c64.CIA2DDRA |= %11
+        return ((c64.CIA2PRA & 3) ^ 3) as uword << 14
+    }
+
+    sub get_char_matrix_ptr() -> uword {
+        ; Usually the character screen matrix is at 1024-2039 (see above)
+        ; However the vic memory configuration can be altered and this moves these registers with it.
+        ; So this routine determines it dynamically from the VIC memory setup.
+        uword chars_matrix_offset = (c64.VMCSB & $f0) as uword << 6
+        return get_vic_memory_base() + chars_matrix_offset
+    }
+
+    sub get_bitmap_ptr() -> uword {
+        return get_vic_memory_base() + ((c64.VMCSB & %00001000) as uword << 10)
+    }
+
+    sub get_sprite_addr_ptrs() -> uword {
+        ; Usually the sprite address pointers are at addresses 2040-2047 (see above)
+        ; However the vic memory configuration can be altered and this moves these registers with it.
+        ; So this routine determines it dynamically from the VIC memory setup.
+        return get_char_matrix_ptr() + 1016
+    }
+
+    sub set_sprite_ptr(ubyte sprite_num, uword sprite_data_address) {
+        ; Sets the sprite data pointer to the given address.
+        ; Because it takes some time to calculate things based on the vic memory setup,
+        ; its only suitable if you're not continuously changing the data address.
+        ; Otherwise store the correct sprite data pointer location somewhere yourself and reuse it.
+        @(get_sprite_addr_ptrs() + sprite_num) = lsb(sprite_data_address / 64)
+    }
 }
 
 sys {

examples/c64/balloonflight.p8

@@ -15,7 +15,7 @@ main {
     ubyte perform_scroll = false
 
     sub start() {
-        c64.SPRPTR[0] = $0f00 / 64
+        c64.set_sprite_ptr(0, $0f00)           ; alternatively, set directly:  c64.SPRPTR[0] = $0f00 / 64
         c64.SPENA = 1
         c64.SP0COL = 14
         c64.SPXY[0] = 80

examples/c64/cube3d-sprites.p8

@@ -171,6 +171,7 @@ main {
 
             c64.SPXYW[i] = mkword(sy, sx)
 
+            ; because we want speed, we don't use the dynamic c64.set_sprite_ptr() here
             if(zc < 30*128)
                 c64.SPRPTR[i] = $2000/64 +1     ; large ball
             else

examples/c64/sprites.p8

@@ -40,7 +40,7 @@ main {
 
         ubyte @zp i
         for i in 0 to 7 {
-            c64.SPRPTR[i] = $0a00 / 64
+            c64.set_sprite_ptr(i, $0a00)           ; alternatively, set directly:  c64.SPRPTR[i] = $0a00 / 64
             c64.SPXY[i*2] = 50+25*i
             c64.SPXY[i*2+1] = math.rnd()
         }

examples/c64/turtle-gfx.p8

@@ -30,19 +30,18 @@ turtle {
     float angle
     bool pendown
 
+    const uword SPRITE_MEMORY = $5800
+
     sub init() {
         xpos = 160.0
         ypos = 100.0
         angle = 0.0
         pendown = true
 
-        const uword SPRITE_MEMORY = $5800
-        const uword SPRITE_ADDR_POINTERS = (graphics.CHARS_ADDRESS & $fc00) + 1016      ; no longer the default location 2040!
-
-        sys.memcopy(&turtlesprite, SPRITE_MEMORY, len(turtlesprite))
-        @(SPRITE_ADDR_POINTERS) = (SPRITE_MEMORY & $3fff) / 64
-        c64.SPENA = 1
-        c64.SP0COL = 5
+        sys.memcopy(&turtlesprite, SPRITE_MEMORY, len(turtlesprite))    ; copy the sprite pixel data
+        c64.set_sprite_ptr(0, SPRITE_MEMORY)        ; use dynamic setter because of changed vic memory layout
+        c64.SPENA = 1       ; sprites on
+        c64.SP0COL = 5      ; green sprite
 
         update_turtle_sprite()
     }

examples/c64/wizzine.p8

@@ -35,7 +35,7 @@ main {
     sub start() {
         ubyte i
         for i in 0 to 7 {
-            c64.SPRPTR[i] = $0a00/64
+            c64.set_sprite_ptr(i, $0a00)           ; alternatively, set directly:  c64.SPRPTR[i] = $0a00 / 64
         }
         c64.SPENA = 255                 ; enable all sprites
         sys.set_rasterirq(&irq.irqhandler, 230, true)     ; enable animation