Fill Routine

[na_th_an]

I'm having problems. A call to the routine seems to mess up something (maybe some register should be preserved?). My routine is simple, quoting the interesting bit:

Code:

While (endOfDrawing > binAddress) cmd = Peek (binAddress) binAddress = binAddress + 1 If cmd < 192 Then x = Peek (binAddress) binAddress = binAddress + 1 y = 191 - cmd dx = x: dx = dx - cx ' ZX Basic doesn't like type mix dy = y: dy = dy - cy ' ZX Basic doesn't like type mix Draw dx, dy cx = x cy = y ElseIf cmd = 192 Then x = Peek (binAddress) y = 191 - Peek (binAddress + 1) binAddress = binAddress + 2 Plot x, y cx = x cy = y ElseIf cmd = 193 Then x = Peek (binAddress) y = Peek (binAddress + 1) ex = Peek (binAddress + 2) binAddress = binAddress + 3 SPPFill (x, y, @gpPatterns + (ex << 3)) End If Wend

Notice the call to SPPFill towards the end of the code. If I comment that line, the vector drawing renders OK (albeit, without fills), but if I leave it uncommented, it somehow messes something so binAddress goes elsewhere and it draws random lines until the program crashes.

I've found that somehow ZX Basic doens't like IX messed with, so if I do:

Code:

Asm push ix End Asm SPPFill (x, y, @gpPatterns + (ex << 3)) Asm pop ix End Asm

It just works! Not a big deal, but I just wanted you to know.

I might have something to publish very soon