adding plasma example

examples/plasma.p8

@@ -0,0 +1,97 @@
+%import c64lib
+%zeropage basicsafe
+
+
+;/*****************************************************************************\
+;** plasma test program for cc65.                                             **
+;**                                                                           **
+;** (w)2001 by groepaz/hitmen                                                 **
+;**                                                                           **
+;** Cleanup and porting by Ullrich von Bassewitz.                             **
+;** Converted to prog8 by Irmen de Jong                                       **
+;**                                                                           **
+;\*****************************************************************************/
+
+main {
+    const uword SCREEN1 = $E000
+    const uword SCREEN2 = $E400
+    const uword CHARSET = $E800
+
+    const ubyte PAGE1 = ((SCREEN1 >> 6) & $F0) | ((CHARSET >> 10) & $0E)
+    const ubyte PAGE2 = ((SCREEN2 >> 6) & $F0) | ((CHARSET >> 10) & $0E)
+
+    sub start() {
+        c64.COLOR = 1
+        c64scr.print("creating charset...")
+        makechar()
+
+        ubyte block = c64.CIA2PRA
+        c64.CIA2PRA = (block & $FC) | (lsb(SCREEN1 >> 14) ^ $03)
+
+        repeat {
+            doplasma(SCREEN1)
+            c64.VMCSB = PAGE1
+            doplasma(SCREEN2)
+            c64.VMCSB = PAGE2
+        }
+    }
+
+    ; several variables outside of doplasma to make them retain their value
+    ubyte c1A
+    ubyte c1B
+    ubyte c2A
+    ubyte c2B
+
+    sub doplasma(uword screen) {
+        ubyte[40] xbuf
+        ubyte[25] ybuf
+        ubyte c1a = c1A
+        ubyte c1b = c1B
+        ubyte c2a = c2A
+        ubyte c2b = c2B
+        ubyte @zp i
+        ubyte @zp ii
+
+        for ii in 0 to 24 {
+            ybuf[ii] = sin8u(c1a) + sin8u(c1b)
+            c1a += 4
+            c1b += 9
+        }
+        c1A += 3
+        c1B -= 5
+        for i in 0 to 39 {
+            xbuf[i] = sin8u(c2a) + sin8u(c2b)
+            c2a += 3
+            c2b += 7
+        }
+        c2A += 2
+        c2B -= 3
+        for ii in 0 to 24 {
+            for i in 0 to 39 {
+                @(screen) = xbuf[i] + ybuf[ii]
+                screen++
+            }
+        }
+    }
+
+    sub makechar() {
+
+        ubyte[8] bittab = [ $01, $02, $04, $08, $10, $20, $40, $80 ]
+        ubyte c
+        for c in 0 to 255 {
+            ubyte @zp s = sin8u(c)
+            ubyte i
+            for i in 0 to 7 {
+                ubyte b=0
+                ubyte @zp ii
+                for ii in 0 to 7 {
+                    ; use 16 bit rng for a bit more randomness instead of the 8-bit rng
+                    if lsb(rndw()) > s {
+                        b |= bittab[ii]
+                    }
+                }
+                @(CHARSET + i + c*8.w) = b
+            }
+        }
+    }
+}

examples/test.p8

@@ -7,15 +7,20 @@ main {
 
     sub start() {
 
-        ubyte A =$22
-        ubyte V
-        uword addr = $c0f0
+        uword zz = $ee22
 
-        @($c000) = 123
+        const uword SCREEN1 = $E000
+        const uword CHARSET = $E800
+        const ubyte PAGE1 = ((SCREEN1 >> 6) & $F0) | ((CHARSET >> 10) & $0E)
+        ubyte cmsb = msb(zz)
+        ubyte clsb = lsb(zz)
 
-        A = @($c022-A)
-
-        c64scr.print_ub(A)
-        c64.CHROUT('\n')
+        c64scr.print("\ncmsb=")
+        c64scr.print_ubhex(cmsb, false)
+        c64scr.print("\nclsb=")
+        c64scr.print_ubhex(clsb, false)
+        c64scr.print("\nPAGE1=")
+        ubyte p1 = PAGE1            ; TODO fix type error of PAGE1
+        c64scr.print_ubhex(PAGE1, false)
     }
 }