lua write callbacks: adding optional third parameter to retrieve the value written, added Sprites.lua script to visualize sprites (requires and demonstrates feature just added)

trunk/output/luaScripts/Sprites.lua

@@ -0,0 +1,45 @@
+-- Simple sprite visualizer
+-- Draws a box around all sprites on screen.
+-- rainwarrior 8/23/2016
+
+sprite_color = "#FF00FF" -- change to customize color
+
+sprite_height_last = 8
+sprite_height = 8
+
+function oam_dma(a,s,v)
+	local oam = v * 256
+	for i=1,64 do
+		local is = (i-1) * 4
+		local x0 = memory.readbyte(oam + is + 3)
+		local x1 = x0 + 7
+		local y0 = memory.readbyte(oam + is + 0) + 1
+		local y1 = y0 + (sprite_height_last - 1)
+		gui.box(x0,y0,x1,y1,"",sprite_color)
+	end
+end
+
+function ppu_ctrl(a,s,v)
+	if AND(v,0x20) == 0 then
+		sprite_height = 8
+	else
+		sprite_height = 16
+	end
+end
+
+function frame_end()
+	-- information about sprite height will be behind by 1 frame
+	-- (or potentially wrong if changed before the end of the frame)
+	-- in most games this doesn't change from frame to frame, though
+	sprite_height_last = sprite_height
+end
+
+-- main
+
+memory.registerwrite(0x4014,1,oam_dma)
+memory.registerwrite(0x2000,1,ppu_ctrl)
+emu.registerafter(frame_end)
+
+while (true) do
+	emu.frameadvance()
+end

trunk/src/lua-engine.cpp

@@ -1976,7 +1976,8 @@ static void CallRegisteredLuaMemHook_LuaMatch(unsigned int address, int size, un
 						//RefreshScriptSpeedStatus();
 						lua_pushinteger(L, address);
 						lua_pushinteger(L, size);
-						int errorcode = lua_pcall(L, 2, 0, 0);
+						lua_pushinteger(L, value);
+						int errorcode = lua_pcall(L, 3, 0, 0);
 						luaRunning /*info.running*/ = wasRunning;
 						//RefreshScriptSpeedStatus();
 						if (errorcode)