From eb2e4a872ab715a3414f99b585d018cce34533f1 Mon Sep 17 00:00:00 2001
From: Thomas <thomas@thomasw.dev>
Date: Thu, 7 Dec 2023 04:05:41 +0100
Subject: [PATCH] Add mode 7 registers

---
 src/snes/ppu/bus.rs | 40 +++++++++++++++++++++++++++++++++++-----
 src/snes/ppu/mod.rs | 23 +++++++++++++++++++++--
 2 files changed, 56 insertions(+), 7 deletions(-)

diff --git a/src/snes/ppu/bus.rs b/src/snes/ppu/bus.rs
index 729a729..21f1528 100644
--- a/src/snes/ppu/bus.rs
+++ b/src/snes/ppu/bus.rs
@@ -3,6 +3,13 @@ use super::*;
 use crate::frontend::Renderer;
 use crate::snes::bus::{Address, BusMember};
 
+macro_rules! write_m7x {
+    ($self:ident, $reg:ident, $val:expr) => {{
+        $self.$reg = (($val as u16) << 8 | $self.m7_old as u16) as i16;
+        $self.m7_old = $val
+    }};
+}
+
 impl<TRenderer> BusMember<Address> for PPU<TRenderer>
 where
     TRenderer: Renderer,
@@ -37,17 +44,17 @@ where
                 //}
                 // MPYL - Signed Multiply Result (lower 8bit) (R)
                 0x2134 => {
-                    let res = i32::from(self.m7a as i16) * i32::from(self.m7b as i8);
+                    let res = i32::from(self.m7a as i16) * i32::from(self.m7b_8b);
                     Some(res as u8)
                 }
                 // MPYM - Signed Multiply Result (middle 8bit) (R)
                 0x2135 => {
-                    let res = i32::from(self.m7a as i16) * i32::from(self.m7b as i8);
+                    let res = i32::from(self.m7a as i16) * i32::from(self.m7b_8b);
                     Some((res >> 8) as u8)
                 }
                 // MPYH - Signed Multiply Result (upper 8bit) (R)
                 0x2136 => {
-                    let res = i32::from(self.m7a as i16) * i32::from(self.m7b as i8);
+                    let res = i32::from(self.m7a as i16) * i32::from(self.m7b_8b);
                     Some((res >> 16) as u8)
                 }
                 // SLHV - Latch H/V-Counter by Software (R)
@@ -182,6 +189,11 @@ where
                     let new = val as u16;
                     self.bgxxofs_prev = val;
 
+                    if idx == 0 {
+                        // M7HOFS
+                        write_m7x!(self, m7hofs, val);
+                    }
+
                     Some(self.bgxhofs[idx] = (new << 8) | (prev & !7) | ((cur >> 8) & 7))
                 }
                 // BGxVOFS - BGx Vertical Scroll (Y) (write-twice)
@@ -191,6 +203,11 @@ where
                     let new = val as u16;
                     self.bgxxofs_prev = val;
 
+                    if idx == 0 {
+                        // M7VOFS
+                        write_m7x!(self, m7vofs, val);
+                    }
+
                     Some(self.bgxvofs[idx] = (new << 8) | prev)
                 }
 
@@ -224,10 +241,23 @@ where
                     self.vram_autoinc(true);
                     Some(self.vram[addr] = (cur & 0xFF) | (val as u16) << 8)
                 }
+                // M7SEL - Rotation/Scaling Mode Settings (W)
+                0x211A => Some(self.m7sel = val),
                 // M7A - Rotation/Scaling Parameter A (and Maths 16bit operand) (W)
-                0x211B => Some(self.m7a = self.m7a >> 8 | (val as u16) << 8),
+                0x211B => Some(write_m7x!(self, m7a, val)),
                 // M7B - Rotation/Scaling Parameter B (and Maths 8bit operand) (W)
-                0x211C => Some(self.m7b = val),
+                0x211C => {
+                    self.m7b_8b = val as i8;
+                    Some(write_m7x!(self, m7b, val))
+                }
+                // M7C - Rotation/Scaling Parameter C (W)
+                0x211D => Some(write_m7x!(self, m7c, val)),
+                // M7D - Rotation/Scaling Parameter D (W)
+                0x211E => Some(write_m7x!(self, m7d, val)),
+                // M7X - Rotation/Scaling Center Coordinate X (W)
+                0x211F => Some(write_m7x!(self, m7x, val)),
+                // M7Y - Rotation/Scaling Center Coordinate Y (W)
+                0x2120 => Some(write_m7x!(self, m7y, val)),
                 // CGADD - Palette CGRAM Address (Color Generator Memory)
                 0x2121 => {
                     self.cgadd.set(val);
diff --git a/src/snes/ppu/mod.rs b/src/snes/ppu/mod.rs
index 8bd3d51..cc27675 100644
--- a/src/snes/ppu/mod.rs
+++ b/src/snes/ppu/mod.rs
@@ -168,8 +168,18 @@ pub struct PPU<TRenderer: Renderer> {
     hlatch: Cell<u8>,
     vlatch: Cell<u8>,
 
-    m7a: u16,
-    m7b: u8,
+    // Mode 7 registers
+    m7sel: u8,
+    m7a: i16,
+    m7b_8b: i8,
+    m7b: i16,
+    m7c: i16,
+    m7d: i16,
+    m7x: i16,
+    m7y: i16,
+    m7hofs: i16,
+    m7vofs: i16,
+    m7_old: u8,
 }
 
 pub struct BgTile<'a> {
@@ -262,8 +272,17 @@ where
             hlatch: Cell::new(0),
             vlatch: Cell::new(0),
 
+            m7sel: 0,
             m7a: 0,
             m7b: 0,
+            m7b_8b: 0,
+            m7c: 0,
+            m7d: 0,
+            m7hofs: 0,
+            m7vofs: 0,
+            m7x: 0,
+            m7y: 0,
+            m7_old: 0,
         }
     }