done some more work on the sprites.. hopefully most are positioned a

bit better now..  
still can't see how they get disabled tho, nor do I understand the
rouge lines on top of some of them.. it either needs perfect precision
or they're some kind of markers like sega used..
lots of bits set in the spriteram we don't use too..  (nw)

src/mame/drivers/cybertnk.c

@@ -304,9 +304,9 @@ static void draw_road(screen_device &screen, bitmap_ind16 &bitmap, const rectang
 static void draw_sprites(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect, int screen_shift)
 {
 	cybertnk_state *state = screen.machine().driver_data<cybertnk_state>();
-	const UINT8 *blit_ram = screen.machine().root_device().memregion("spr_gfx")->base();
+	const UINT32 *sprrom = (UINT32*)screen.machine().root_device().memregion("spr_gfx")->base();
-	int offs,x,y,z,xsize,ysize,yi,xi,col_bank,fx,zoom;
+	int offs,x,y,xsize,ysize,yi,xi,col_bank,fx,zoom;
-	UINT32 spr_offs,spr_offs_helper;
+	UINT32 spr_offs,line_start_spr_offset;
 	int xf,yf,xz,yz;
 	const pen_t *paldata = screen.machine().pens;
 
@@ -316,130 +316,135 @@ static void draw_sprites(screen_device &screen, bitmap_ind16 &bitmap, const rect
 	int	maxx = cliprect.max_x;
 	UINT16* dest;
 
+	/*
+
+	o = offset
+	y = ypos  Y = ysize
+	x = xpos  X = xsize f = flipx
+
+	Z = zoom
+	C = colour
+                            +word offset
+	 CCCC CCCC ---- -ooo   0x0
+	 oooo oooo oooo oooo   0x1
+	 ---- ---- ---y yyyy   0x2
+	 ---- ---- ---- ----   0x3
+	 ---- ---- ---- YYYY   0x4
+	 f--- --xx xxxx xxxx   0x5
+	 ZZZZ ZZZZ ---- XXXX   0x6
+	 ---- ---- ---- ----   0x7
+
+	*/
+
 
 	for(offs=0;offs<0x1000/2;offs+=8)
 	{
-		z = (state->m_spr_ram[offs+(0x6/2)] & 0xffff);
+		// todo, how are sprites really disabled? our gunshots etc. still leave trails with this logic
-		if(z == 0xffff || state->m_spr_ram[offs+(0x0/2)] == 0x0000) //TODO: check the correct bit
-			continue;
-		x = (state->m_spr_ram[offs+(0xa/2)] & 0x3ff);
-		y = (state->m_spr_ram[offs+(0x4/2)] & 0xff);
-		if(state->m_spr_ram[offs+(0x4/2)] & 0x100)
-			y = 0x100 - y;
-		spr_offs = (((state->m_spr_ram[offs+(0x0/2)] & 7) << 16) | (state->m_spr_ram[offs+(0x2/2)])) << 2;
-		xsize = ((state->m_spr_ram[offs+(0xc/2)] & 0x000f)+1) << 3;
-		ysize = (state->m_spr_ram[offs+(0x8/2)] & 0x00ff)+1;
-		fx = (state->m_spr_ram[offs+(0xa/2)] & 0x8000) >> 15;
-		zoom = (state->m_spr_ram[offs+(0xc/2)] & 0xff00) >> 8;
 
-		col_bank = (state->m_spr_ram[offs+(0x0/2)] & 0xff00) >> 8;
+		if ((state->m_spr_ram[offs+0x3]) == 0xffff)
+			continue;
+
+		if ((state->m_spr_ram[offs+0x0]) == 0x0000)
+			continue;
+
+
+		x = (state->m_spr_ram[offs+0x5] & 0x3ff);
+		if (x&0x200) x-=0x400;
+
+		y = (state->m_spr_ram[offs+0x2] & 0x1ff);
+		if (y&0x100) y-=0x200;
+
+
+		spr_offs = (((state->m_spr_ram[offs+0x0] & 7) << 16) | (state->m_spr_ram[offs+0x1]));
+		xsize = ((state->m_spr_ram[offs+0x6] & 0x000f)+1) << 3;
+		ysize = (state->m_spr_ram[offs+0x4] & 0x00ff)+1;
+		fx = (state->m_spr_ram[offs+0x5] & 0x8000) >> 15;
+		zoom = (state->m_spr_ram[offs+0x6] & 0xff00) >> 8;
+
+
+		col_bank = (state->m_spr_ram[offs+0x0] & 0xff00) >> 8;
 
 		xf = 0;
 		yf = 0;
 		xz = 0;
 		yz = 0;
 
+		line_start_spr_offset = spr_offs;
+
+
 		for(yi = 0;yi < ysize;yi++)
 		{
 			xf = xz = 0;
-			spr_offs_helper = spr_offs;
+			
+
 			int yy = y+yz;
 
 			if ((yy>=miny) && (yy<=maxy))
 			{
 				dest = &bitmap.pix16(yy, 0);	
 
-				for(xi=0;xi < xsize;xi+=8)
+				int start,end,inc;
+
+				if (!fx)
+				{
+					start = 0;
+					end = xsize;
+					inc = 8;
+				}
+				else
+				{
+					start = xsize-8;
+					end = -8;
+					inc = -8;
+				}
+
+				for(xi=start;xi != end;xi+=inc)
 				{ // start x loop
 					UINT32 color;
+					
+					color = sprrom[line_start_spr_offset+xi/8];
+			
 					UINT16 dot;
-					int shift_pen, x_dec; //helpers
+					int x_dec; //helpers
 
-					// 4 bytes = 8 pixels..
+					int shift_pen = 0;
-					color = ((blit_ram[spr_offs+0] & 0xff) << 24);
-					color|= ((blit_ram[spr_offs+1] & 0xff) << 16);
-					color|= ((blit_ram[spr_offs+2] & 0xff) << 8);
-					color|= ((blit_ram[spr_offs+3] & 0xff) << 0);
 
-					shift_pen = 28;
 					x_dec = 0;
 
-					// draw 4 pixels
+					// draw 8 pixels
-					while(x_dec < 4 && x_dec+xi <= xsize)
+					while(x_dec < 8)
+					{
+						if (!fx)
 						{
 							dot = (color >> shift_pen) & 0xf;
+						}
+						else
+						{
+							dot = (color >> (28-shift_pen)) & 0xf;
+						}
+
 						if(dot != 0) // transparent pen
 						{
 							dot|= col_bank<<4;
 
-							if(fx)
+							int xx = (x+xz)+screen_shift;
-							{
-								int xx = x+xsize-(xz)+screen_shift;
 							CYBERTNK_DRAWPIXEL
 						}
-							else
-							{
-								int xx = x+xz+screen_shift;
-								CYBERTNK_DRAWPIXEL
-							}
-						}
 						xf+=zoom;
 						if(xf >= 0x100)
 						{
 							xz++;
 							xf-=0x100;
 						}
-						else
+						else // next source pixel
 						{
-							shift_pen -= 8;
+							shift_pen += 4;
 							x_dec++;
 							if(xf >= 0x80) { xz++; xf-=0x80; }
 						}
 					}
-
-					shift_pen = 24;
-					x_dec = 4;
-
-					// draw 4 pixels
-					while(x_dec < 8 && x_dec+xi <= xsize)
-					{
-						dot = (color >> shift_pen) & 0xf;
-						if(dot != 0) // transparent pen
-						{
-							dot|= col_bank<<4;
-
-							if(fx)
-							{
-								int xx = x+xsize-(xz)+screen_shift;
-								CYBERTNK_DRAWPIXEL
-							}
-							else
-							{
-								int xx = x+xz+screen_shift;
-								CYBERTNK_DRAWPIXEL
-
-							}
-						}
-						xf+=zoom;
-						if(xf >= 0x100)
-						{
-							xz++;
-							xf-=0x100;
-						}
-						else
-						{
-							shift_pen -= 8;
-							x_dec++;
-							if(xf >= 0x80) { xz++; xf-=0x80; }
-						}
-					}
-					spr_offs+=4;
 				} // end x loop
 			}
-			else
-			{
-				spr_offs+=xsize/8;
-			}
 
 
 			yf+=zoom;
@@ -447,13 +452,16 @@ static void draw_sprites(screen_device &screen, bitmap_ind16 &bitmap, const rect
 			{
 				yi--;
 				yz++;
-				spr_offs = spr_offs_helper;
 				yf-=0x100;
 			}
+			else // next line
+			{
+				line_start_spr_offset += xsize/8;
 				if(yf >= 0x80) { yz++; yf-=0x80; }
 			}
 		}
 	}		
+}
 
 
 static UINT32 update_screen(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect, int screen_shift)
@@ -957,4 +965,18 @@ ROM_START( cybertnk )
 	ROM_LOAD( "ic30", 0x0260, 0x0020, CRC(2bb6033f) SHA1(eb994108734d7d04f8e293eca21bb3051a63cfe9) )
 ROM_END
 
-GAME( 1988, cybertnk,  0,       cybertnk,  cybertnk,  0, ROT0, "Coreland", "Cyber Tank (v1.04)", GAME_NOT_WORKING ) // it boots as 1.4, not 1.04?
+DRIVER_INIT( cybertnk )
+{
+	UINT32 *spr = (UINT32*)machine.root_device().memregion("spr_gfx")->base();
+
+	for (int x = 0; x< 0x200000/4;x++)
+	{
+		// reorder the data to simplify sprite drawing
+		// we draw 8 pixels at a time, each each nibble contains a pixel, however the original order of 32-bits (8 pixels)
+		// is along the lines of 04 15 26 37 which is awkward to use
+		spr[x] = BITSWAP32(spr[x],  27,26,25,24,   19,18,17,16,  11,10,9,8,  3,2,1,0, 31,30,29,28,   23,22,21,20,   15,14,13,12,   7,6,5,4 );
+	}
+
+}
+
+GAME( 1988, cybertnk,  0,       cybertnk,  cybertnk,  cybertnk, ROT0, "Coreland", "Cyber Tank (v1.4)", GAME_NOT_WORKING )