Add new changes to screen deo function

1 files changed, 19 insertions, 23 deletions

diff --git a/src/devices.c b/src/devices.c
index 49fc4ac..6c7f281 100644
--- a/src/devices.c
+++ b/src/devices.c
@@ -63,43 +63,39 @@ deo_screen(u8 *dev, u8 port) {
             break;
         }
         case 0xf: {
-            u16 x, y, dx, dy, addr;
-            u8 n, twobpp = !!(dev[0xf] & 0x80);
-            x    = PEEK2(dev + 0x8);
-            y    = PEEK2(dev + 0xa);
-            addr = PEEK2(dev + 0xc);
-            n = dev[0x6] >> 4;
-            dx = (dev[0x6] & 0x01) << 3;
-            dy = (dev[0x6] & 0x02) << 2;
-            if(addr > 0x10000 - ((n + 1) << (3 + twobpp))) {
-                return;
-            }
+            u8 ctrl = dev[0xf];
+            u8 move = dev[0x6];
+            u8 length = move >> 4;
+            u8 twobpp = !!(ctrl & 0x80);
             u8 *layer = (dev[0xf] & 0x40) ? FG_BACK : BG_BACK;
-            u8 color = dev[0xf] & 0xf;
-            u8 flipx = dev[0xf] & 0x10;
-            u8 flipy = dev[0xf] & 0x20;
-            for(size_t i = 0; i <= n; i++) {
+            u8 color = ctrl & 0xf;
+            u16 x = PEEK2(dev + 0x8), dx = (move & 0x1) << 3;
+            u16 y = PEEK2(dev + 0xa), dy = (move & 0x2) << 2;
+            u16 addr = PEEK2(dev + 0xc), addr_incr = (move & 0x4) << (1 + twobpp);
+            int flipx = (ctrl & 0x10), fx = flipx ? -1 : 1;
+            int flipy = (ctrl & 0x20), fy = flipy ? -1 : 1;
+            for(size_t i = 0; i <= length; i++) {
                 u8 *sprite = &uxn_ram[addr];
                 if (twobpp) {
                     PROF(ppu_2bpp(layer,
-                                x + dy * i,
-                                y + dx * i,
+                                x + dy * i * fx,
+                                y + dx * i * fy,
                                 sprite,
                                 color,
                                 flipx, flipy), ppu_chr_cycles);
                 } else {
                     PROF(ppu_1bpp(layer,
-                                x + dy * i,
-                                y + dx * i,
+                                x + dy * i * fx,
+                                y + dx * i * fy,
                                 sprite,
                                 color,
                                 flipx, flipy), ppu_icn_cycles);
                 }
-                addr += (dev[0x6] & 0x04) << (1 + twobpp);
+                addr += addr_incr;
             }
-            POKE2(dev + 0xc, addr);   /* auto addr+length */
-            POKE2(dev + 0x8, x + dx); /* auto x+8 */
-            POKE2(dev + 0xa, y + dy); /* auto y+8 */
+            if(move & 0x1) POKE2(dev + 0x8, x + dx * fx); /* auto x+8 */
+            if(move & 0x2) POKE2(dev + 0xa, y + dy * fy); /* auto y+8 */
+            if(move & 0x4) POKE2(dev + 0xc, addr);        /* auto addr+length */
             break;
         }
     }