From b60ad3114c482b1519879a3eb23cc6a83c0c7fe1 Mon Sep 17 00:00:00 2001
From: Michel Heily <michelheily@gmail.com>
Date: Wed, 20 May 2020 21:22:30 +0300
Subject: [PATCH] core: Decouple SysBus from Gpu and re-implement Gpu::update

Former-commit-id: 6ca6989192f0925f4d2eb0e5029a2bcf66869ee9
Former-commit-id: 562d89f627a9e3a9153a7a0db6830fd9b5875967
---
 rustboyadvance-core/src/dma.rs     | 19 +++++++-------
 rustboyadvance-core/src/gba.rs     |  2 +-
 rustboyadvance-core/src/gpu/mod.rs | 42 +++++++++++++++---------------
 rustboyadvance-core/src/sysbus.rs  |  7 +++++
 4 files changed, 38 insertions(+), 32 deletions(-)

diff --git a/rustboyadvance-core/src/dma.rs b/rustboyadvance-core/src/dma.rs
index 2dbfa72..42814d8 100644
--- a/rustboyadvance-core/src/dma.rs
+++ b/rustboyadvance-core/src/dma.rs
@@ -238,17 +238,9 @@ impl DmaController {
         }
     }
 
-    pub fn notify_vblank(&mut self) {
+    pub fn notify_from_gpu(&mut self, timing: u16) {
         for i in 0..4 {
-            if self.channels[i].ctrl.is_enabled() && self.channels[i].ctrl.timing() == 1 {
-                self.pending_set |= 1 << i;
-            }
-        }
-    }
-
-    pub fn notify_hblank(&mut self) {
-        for i in 0..4 {
-            if self.channels[i].ctrl.is_enabled() && self.channels[i].ctrl.timing() == 2 {
+            if self.channels[i].ctrl.is_enabled() && self.channels[i].ctrl.timing() == timing {
                 self.pending_set |= 1 << i;
             }
         }
@@ -267,6 +259,13 @@ impl DmaController {
     }
 }
 
+pub const TIMING_VBLANK: u16 = 1;
+pub const TIMING_HBLANK: u16 = 2;
+
+pub trait DmaNotifer {
+    fn notify(&mut self, timing: u16);
+}
+
 bitfield! {
     #[derive(Serialize, Deserialize, Clone, Default)]
     pub struct DmaChannelCtrl(u16);
diff --git a/rustboyadvance-core/src/gba.rs b/rustboyadvance-core/src/gba.rs
index 0193efb..b1c31a7 100644
--- a/rustboyadvance-core/src/gba.rs
+++ b/rustboyadvance-core/src/gba.rs
@@ -235,9 +235,9 @@ impl GameBoyAdvance {
         io.timers.update(cycles, &mut self.sysbus, &mut irqs);
         io.gpu.update(
             cycles,
-            &mut self.sysbus,
             &mut irqs,
             &mut cycles_to_next_event,
+            self.sysbus.as_mut(),
             &self.video_device,
         );
         io.sound
diff --git a/rustboyadvance-core/src/gpu/mod.rs b/rustboyadvance-core/src/gpu/mod.rs
index be0c762..453306a 100644
--- a/rustboyadvance-core/src/gpu/mod.rs
+++ b/rustboyadvance-core/src/gpu/mod.rs
@@ -4,9 +4,10 @@ use std::rc::Rc;
 
 use serde::{Deserialize, Serialize};
 
+use super::dma::{DmaNotifer, TIMING_HBLANK, TIMING_VBLANK};
 use super::interrupt::IrqBitmask;
 pub use super::sysbus::consts::*;
-use super::sysbus::{BoxedMemory, SysBus};
+use super::sysbus::BoxedMemory;
 use super::VideoInterface;
 use super::{Addr, Bus};
 
@@ -434,13 +435,15 @@ impl Gpu {
         &self.frame_buffer
     }
 
-    pub fn on_state_completed(
+    pub fn on_state_completed<D>(
         &mut self,
         completed: GpuState,
-        sb: &mut SysBus,
         irqs: &mut IrqBitmask,
+        dma_notifier: &mut D,
         video_device: &VideoDeviceRcRefCell,
-    ) {
+    ) where
+        D: DmaNotifer,
+    {
         match completed {
             HDraw => {
                 // Transition to HBlank
@@ -451,7 +454,7 @@ impl Gpu {
                 if self.dispstat.hblank_irq_enable() {
                     irqs.set_LCD_HBlank(true);
                 };
-                sb.io.dmac.notify_hblank();
+                dma_notifier.notify(TIMING_HBLANK);
             }
             HBlank => {
                 self.update_vcount(self.vcount + 1, irqs);
@@ -479,7 +482,7 @@ impl Gpu {
                         irqs.set_LCD_VBlank(true);
                     };
 
-                    sb.io.dmac.notify_vblank();
+                    dma_notifier.notify(TIMING_VBLANK);
                     video_device.borrow_mut().render(&self.frame_buffer);
                     self.obj_buffer_reset();
                     self.cycles_left_for_current_state = CYCLES_HDRAW;
@@ -513,27 +516,24 @@ impl Gpu {
     }
 
     // Returns the new gpu state
-    pub fn update(
+    pub fn update<D>(
         &mut self,
-        cycles: usize,
-        sb: &mut SysBus,
+        mut cycles: usize,
         irqs: &mut IrqBitmask,
         cycles_to_next_event: &mut usize,
+        dma_notifier: &mut D,
         video_device: &VideoDeviceRcRefCell,
-    ) {
-        if self.cycles_left_for_current_state <= cycles {
-            let overshoot = cycles - self.cycles_left_for_current_state;
-
-            self.on_state_completed(self.state, sb, irqs, video_device);
-
-            // handle the overshoot
-            if overshoot < self.cycles_left_for_current_state {
-                self.cycles_left_for_current_state -= overshoot;
+    ) where
+        D: DmaNotifer,
+    {
+        loop {
+            if self.cycles_left_for_current_state <= cycles {
+                cycles -= self.cycles_left_for_current_state;
+                self.on_state_completed(self.state, irqs, dma_notifier, video_device);
             } else {
-                panic!("OH SHIT");
+                self.cycles_left_for_current_state -= cycles;
+                break;
             }
-        } else {
-            self.cycles_left_for_current_state -= cycles;
         }
 
         if self.cycles_left_for_current_state < *cycles_to_next_event {
diff --git a/rustboyadvance-core/src/sysbus.rs b/rustboyadvance-core/src/sysbus.rs
index 787366e..b3c0ea7 100644
--- a/rustboyadvance-core/src/sysbus.rs
+++ b/rustboyadvance-core/src/sysbus.rs
@@ -4,6 +4,7 @@ use std::ops::{Deref, DerefMut};
 use serde::{Deserialize, Serialize};
 
 use super::cartridge::Cartridge;
+use super::dma::DmaNotifer;
 use super::iodev::{IoDevices, WaitControl};
 use super::{Addr, Bus};
 
@@ -377,3 +378,9 @@ impl Bus for SysBus {
         memory_map!(write(self, write_8, addr, value));
     }
 }
+
+impl DmaNotifer for SysBus {
+    fn notify(&mut self, timing: u16) {
+        self.io.dmac.notify_from_gpu(timing);
+    }
+}