From 12f9bb51c180c296441f49ded93cd75d3a7ad035 Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Sun, 1 May 2022 18:53:11 -0300
Subject: [PATCH] feat: stub mode 1 and 2

---
 src/cpu/thumb/data_transfer.zig |  2 +-
 src/ppu.zig                     | 47 +++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/src/cpu/thumb/data_transfer.zig b/src/cpu/thumb/data_transfer.zig
index 542ffee..d299908 100644
--- a/src/cpu/thumb/data_transfer.zig
+++ b/src/cpu/thumb/data_transfer.zig
@@ -25,7 +25,7 @@ pub fn format78(comptime op: u2, comptime T: bool) InstrFn {
             const rb = opcode >> 3 & 0x7;
             const rd = opcode & 0x7;
 
-            const address = cpu.r[rb] + cpu.r[ro];
+            const address = cpu.r[rb] +% cpu.r[ro];
 
             if (T) {
                 // Format 8
diff --git a/src/ppu.zig b/src/ppu.zig
index f1e566c..6709fb9 100644
--- a/src/ppu.zig
+++ b/src/ppu.zig
@@ -135,6 +135,7 @@ pub const Ppu = struct {
             if (maybe_sprites) |sprite| {
                 // Move on to the next sprite If its of a different priority
                 if (sprite.priority() != prio) continue :sprite_loop;
+                if (sprite.attr0.rot_scaling.read()) continue :sprite_loop; // TODO: Affine Sprites
 
                 var i: u9 = 0;
                 px_loop: while (i < sprite.width) : (i += 1) {
@@ -302,6 +303,52 @@ pub const Ppu = struct {
                 std.mem.set(?u16, &self.scanline_buf, null);
                 std.mem.set(?Sprite, &self.scanline_sprites, null);
             },
+            0x1 => {
+                const fb_base = framebuf_pitch * @as(usize, scanline);
+                if (obj_enable) self.fetchSprites();
+
+                var layer: usize = 0;
+                while (layer < 4) : (layer += 1) {
+                    self.drawSprites(@truncate(u2, layer));
+                    if (layer == self.bg[0].cnt.priority.read() and bg_enable & 1 == 1) self.drawBackround(0);
+                    if (layer == self.bg[1].cnt.priority.read() and bg_enable >> 1 & 1 == 1) self.drawBackround(1);
+                    // TODO: Implement Affine BG2
+                }
+
+                // Copy Drawn Scanline to Frame Buffer
+                // If there are any nulls present in self.scanline_buf it means that no background drew a pixel there, so draw backdrop
+                for (self.scanline_buf) |maybe_px, i| {
+                    const bgr555 = if (maybe_px) |px| px else self.palette.getBackdrop();
+                    std.mem.copy(u8, self.framebuf[fb_base + i * @sizeOf(u32) ..][0..4], &intToBytes(u32, toRgba8888(bgr555)));
+                }
+
+                // Reset Current Scanline Pixel Buffer and list of fetched sprites
+                // in prep for next scanline
+                std.mem.set(?u16, &self.scanline_buf, null);
+                std.mem.set(?Sprite, &self.scanline_sprites, null);
+            },
+            0x2 => {
+                const fb_base = framebuf_pitch * @as(usize, scanline);
+                if (obj_enable) self.fetchSprites();
+
+                var layer: usize = 0;
+                while (layer < 4) : (layer += 1) {
+                    self.drawSprites(@truncate(u2, layer));
+                    // TODO: Implement Affine BG2, BG3
+                }
+
+                // Copy Drawn Scanline to Frame Buffer
+                // If there are any nulls present in self.scanline_buf it means that no background drew a pixel there, so draw backdrop
+                for (self.scanline_buf) |maybe_px, i| {
+                    const bgr555 = if (maybe_px) |px| px else self.palette.getBackdrop();
+                    std.mem.copy(u8, self.framebuf[fb_base + i * @sizeOf(u32) ..][0..4], &intToBytes(u32, toRgba8888(bgr555)));
+                }
+
+                // Reset Current Scanline Pixel Buffer and list of fetched sprites
+                // in prep for next scanline
+                std.mem.set(?u16, &self.scanline_buf, null);
+                std.mem.set(?Sprite, &self.scanline_sprites, null);
+            },
             0x3 => {
                 const vram_base = width * @sizeOf(u16) * @as(usize, scanline);
                 const fb_base = framebuf_pitch * @as(usize, scanline);