From 6b33c97881d67cf0318ab0bfd9a1802219feb339 Mon Sep 17 00:00:00 2001
From: Thomas <thomas@thomasw.dev>
Date: Sat, 9 Dec 2023 06:22:45 +0100
Subject: [PATCH] Handle screenover in mode 7

---
 src/snes/ppu/render_m7.rs  | 20 ++++++++++++++++++--
 src/test/peterlemon_ppu.rs | 13 +++++++++++++
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/src/snes/ppu/render_m7.rs b/src/snes/ppu/render_m7.rs
index a768af6..61a0fd2 100644
--- a/src/snes/ppu/render_m7.rs
+++ b/src/snes/ppu/render_m7.rs
@@ -7,8 +7,24 @@ where
     TRenderer: Renderer,
 {
     fn mode7_vram_to_color(&self, vram_x: i32, vram_y: i32) -> u8 {
-        let tile_x = ((vram_x as u32 >> 11) & 0x7f) as u16;
-        let tile_y = ((vram_y as u32 >> 11) & 0x7f) as u16;
+        let screenover = (self.m7sel >> 6) & 0x03;
+        let overflow = (vram_x >> 18) | (vram_y >> 18) != 0;
+
+        if overflow && (screenover == 2) {
+            // Overflow -> transparent
+            return 0;
+        }
+
+        let (tile_x, tile_y) = if overflow && (screenover == 3) {
+            // Overflow -> Tile 0
+            (0, 0)
+        } else {
+            // Overflow -> Wrap
+            (
+                ((vram_x as u32 >> 11) & 0x7f) as u16,
+                ((vram_y as u32 >> 11) & 0x7f) as u16,
+            )
+        };
         let pixel_x = ((vram_x >> 8) & 0x07) as u16;
         let pixel_y = ((vram_y >> 8) & 0x07) as u16;
 
diff --git a/src/test/peterlemon_ppu.rs b/src/test/peterlemon_ppu.rs
index c65def1..776232c 100644
--- a/src/test/peterlemon_ppu.rs
+++ b/src/test/peterlemon_ppu.rs
@@ -98,3 +98,16 @@ ppu_test!(
     "Window/WindowMultiHDMA/WindowMultiHDMA.sfc",
     "688de105142b1b28b1c0bb0473e518f1beada64623c9352e58f71341da1dbf19"
 );
+
+// Mode 7 tests
+ppu_test!(
+    Mode7RotZoom,
+    "Mode7/RotZoom/RotZoom.sfc",
+    "4235ddbbc79e0a5f3f2ebe075eb23e328a63a8ba0de6949d320747668790ab91"
+);
+ppu_test!(
+    // Tests screenover (transoarent)
+    Mode7Perspective,
+    "Mode7/Perspective/Perspective.sfc",
+    "48993ffece6707ea3c64ad4a9c3096ec81215fd5dda1f9a5aaff18ee31e6c616"
+);