From 1b1b855702ecf33f8888c7b74b16034e323f17f4 Mon Sep 17 00:00:00 2001
From: Michel Heily <michelheily@gmail.com>
Date: Sat, 30 May 2020 14:32:03 +0300
Subject: [PATCH] core/gpu: Impl bitmap mode 5 and properly handle wraparound
 for bitmap modes.

resolves #90


Former-commit-id: 633580870e2d44d95a8b53b6311232f0fad48bd9
Former-commit-id: aa2ba32116900f635f12f9dcc9d29344367711eb
---
 core/src/gpu/mod.rs           |  4 +++
 core/src/gpu/render.rs        |  5 +++
 core/src/gpu/render/bitmap.rs | 65 +++++++++++++++++++++++++++++------
 3 files changed, 64 insertions(+), 10 deletions(-)

diff --git a/core/src/gpu/mod.rs b/core/src/gpu/mod.rs
index 37c1d2a..97fed96 100644
--- a/core/src/gpu/mod.rs
+++ b/core/src/gpu/mod.rs
@@ -384,6 +384,10 @@ impl Gpu {
                 self.render_mode4(2);
                 self.finalize_scanline(2, 2);
             }
+            5 => {
+                self.render_mode5(2);
+                self.finalize_scanline(2, 2);
+            }
             _ => panic!("{:?} not supported", self.dispcnt.mode()),
         }
         // self.mosaic_sfx();
diff --git a/core/src/gpu/render.rs b/core/src/gpu/render.rs
index a884aa6..eed2449 100644
--- a/core/src/gpu/render.rs
+++ b/core/src/gpu/render.rs
@@ -36,6 +36,11 @@ pub(super) static SCREEN_VIEWPORT: ViewPort = ViewPort {
     w: DISPLAY_WIDTH as i32,
     h: DISPLAY_HEIGHT as i32,
 };
+pub(super) static MODE5_VIEWPORT: ViewPort = ViewPort {
+    origin: (0, 0),
+    w: 160,
+    h: 128,
+};
 
 pub(super) mod utils {
     use super::Point;
diff --git a/core/src/gpu/render/bitmap.rs b/core/src/gpu/render/bitmap.rs
index 641679f..ba9185c 100644
--- a/core/src/gpu/render/bitmap.rs
+++ b/core/src/gpu/render/bitmap.rs
@@ -4,7 +4,7 @@ use super::super::consts::*;
 use super::super::Gpu;
 use super::super::Rgb15;
 
-use super::{utils, SCREEN_VIEWPORT};
+use super::{utils, MODE5_VIEWPORT, SCREEN_VIEWPORT};
 
 use crate::Bus;
 
@@ -16,13 +16,19 @@ impl Gpu {
         let pc = self.bg_aff[bg - 2].pc as i32;
         let ref_point = self.get_ref_point(bg);
 
-        for x in 0..DISPLAY_WIDTH {
-            let t = utils::transform_bg_point(ref_point, x as i32, pa, pc);
-            if !SCREEN_VIEWPORT.contains_point(t) {
-                self.backgrounds[bg].line[x] = Rgb15::TRANSPARENT;
-                continue;
-            }
+        let wraparound = self.backgrounds[bg].bgcnt.affine_wraparound();
 
+        for x in 0..DISPLAY_WIDTH {
+            let mut t = utils::transform_bg_point(ref_point, x as i32, pa, pc);
+            if !SCREEN_VIEWPORT.contains_point(t) {
+                if wraparound {
+                    t.0 = t.0.rem_euclid(SCREEN_VIEWPORT.w);
+                    t.1 = t.1.rem_euclid(SCREEN_VIEWPORT.h);
+                } else {
+                    self.backgrounds[bg].line[x] = Rgb15::TRANSPARENT;
+                    continue;
+                }
+            }
             let pixel_index = index2d!(u32, t.0, t.1, DISPLAY_WIDTH);
             let pixel_ofs = 2 * pixel_index;
             let color = Rgb15(self.vram.read_16(pixel_ofs));
@@ -43,11 +49,18 @@ impl Gpu {
         let pc = self.bg_aff[bg - 2].pc as i32;
         let ref_point = self.get_ref_point(bg);
 
+        let wraparound = self.backgrounds[bg].bgcnt.affine_wraparound();
+
         for x in 0..DISPLAY_WIDTH {
-            let t = utils::transform_bg_point(ref_point, x as i32, pa, pc);
+            let mut t = utils::transform_bg_point(ref_point, x as i32, pa, pc);
             if !SCREEN_VIEWPORT.contains_point(t) {
-                self.backgrounds[bg].line[x] = Rgb15::TRANSPARENT;
-                continue;
+                if wraparound {
+                    t.0 = t.0.rem_euclid(SCREEN_VIEWPORT.w);
+                    t.1 = t.1.rem_euclid(SCREEN_VIEWPORT.h);
+                } else {
+                    self.backgrounds[bg].line[x] = Rgb15::TRANSPARENT;
+                    continue;
+                }
             }
             let bitmap_index = index2d!(u32, t.0, t.1, DISPLAY_WIDTH);
             let bitmap_ofs = page_ofs + (bitmap_index as u32);
@@ -56,4 +69,36 @@ impl Gpu {
             self.backgrounds[bg].line[x] = color;
         }
     }
+
+    pub(in super::super) fn render_mode5(&mut self, bg: usize) {
+        let page_ofs: u32 = match self.dispcnt.display_frame() {
+            0 => 0x0600_0000 - VRAM_ADDR,
+            1 => 0x0600_a000 - VRAM_ADDR,
+            _ => unreachable!(),
+        };
+
+        let _y = self.vcount;
+
+        let pa = self.bg_aff[bg - 2].pa as i32;
+        let pc = self.bg_aff[bg - 2].pc as i32;
+        let ref_point = self.get_ref_point(bg);
+
+        let wraparound = self.backgrounds[bg].bgcnt.affine_wraparound();
+
+        for x in 0..DISPLAY_WIDTH {
+            let mut t = utils::transform_bg_point(ref_point, x as i32, pa, pc);
+            if !MODE5_VIEWPORT.contains_point(t) {
+                if wraparound {
+                    t.0 = t.0.rem_euclid(MODE5_VIEWPORT.w);
+                    t.1 = t.1.rem_euclid(MODE5_VIEWPORT.h);
+                } else {
+                    self.backgrounds[bg].line[x] = Rgb15::TRANSPARENT;
+                    continue;
+                }
+            }
+            let pixel_ofs = page_ofs + 2 * index2d!(u32, t.0, t.1, MODE5_VIEWPORT.w);
+            let color = Rgb15(self.vram.read_16(pixel_ofs));
+            self.backgrounds[bg].line[x] = color;
+        }
+    }
 }