From f61e3f9e65eb59bfd6851cc8267b9cbcae53ed9e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Magalh=C3=A3es?= <joamag@gmail.com>
Date: Mon, 15 May 2023 17:38:13 +0100
Subject: [PATCH] feat: support for speed switching With initial approach for
scalling down the speed of other components.
---
frontends/sdl/src/main.rs | 9 ++++++---
src/apu.rs | 31 +++++++++++++++++++++++++++++++
src/cpu.rs | 5 +++++
src/gb.rs | 24 ++++++++++++++++++++++--
src/mmu.rs | 11 ++++-------
5 files changed, 68 insertions(+), 12 deletions(-)
diff --git a/frontends/sdl/src/main.rs b/frontends/sdl/src/main.rs
index e6990a2a..fb789d0a 100644
--- a/frontends/sdl/src/main.rs
+++ b/frontends/sdl/src/main.rs
@@ -349,9 +349,12 @@ impl Emulator {
// calculates the number of cycles that are meant to be the target
// for the current "tick" operation this is basically the current
- // logic frequency divided by the visual one
- let cycle_limit =
- (self.logic_frequency as f32 / self.visual_frequency).round() as u32;
+ // logic frequency divided by the visual one, this operation also
+ // takes into account the current Game Boy speed multiplier (GBC)
+ let cycle_limit = (self.logic_frequency as f32
+ * self.system.speed().multiplier() as f32
+ / self.visual_frequency)
+ .round() as u32;
loop {
// limits the number of ticks to the typical number
diff --git a/src/apu.rs b/src/apu.rs
index c1c41c94..d2b9f657 100644
--- a/src/apu.rs
+++ b/src/apu.rs
@@ -330,6 +330,24 @@ impl Apu {
pub fn read(&mut self, addr: u16) -> u8 {
match addr {
+ // 0xFF11 — NR11: Channel 1 length timer & duty cycle
+ 0xff11 => (self.ch1_wave_duty & 0x03) << 6,
+ // 0xFF12 — NR12: Channel 1 volume & envelope
+ 0xff12 => {
+ (self.ch1_pace & 0x07)
+ | ((self.ch1_direction & 0x01) << 3)
+ | ((self.ch1_volume & 0x0f) << 4)
+ }
+
+ // 0xFF16 — NR21: Channel 2 length timer & duty cycle
+ 0xff16 => (self.ch2_wave_duty & 0x03) << 6,
+ // 0xFF17 — NR22: Channel 2 volume & envelope
+ 0xff17 => {
+ (self.ch2_pace & 0x07)
+ | ((self.ch2_direction & 0x01) << 3)
+ | ((self.ch2_volume & 0x0f) << 4)
+ }
+
// 0xFF1A — NR30: Channel 3 DAC enable
0xff1a => {
if self.ch3_dac {
@@ -338,6 +356,19 @@ impl Apu {
0x00
}
}
+ // 0xFF1B — NR31: Channel 3 length timer
+ 0xff1b => 0x00,
+ // 0xFF1C — NR32: Channel 3 output level
+ 0xff1c => (self.ch3_output_level & 0x03) << 5,
+
+ // 0xFF20 — NR41: Channel 4 length timer
+ 0xff20 => 0x00,
+ // 0xFF21 — NR42: Channel 4 volume & envelope
+ 0xff21 => {
+ (self.ch4_pace & 0x07)
+ | ((self.ch4_direction & 0x01) << 3)
+ | ((self.ch4_volume & 0x0f) << 4)
+ }
// 0xFF25 — NR51: Sound panning
0xff25 => self.glob_panning,
diff --git a/src/cpu.rs b/src/cpu.rs
index 440c5995..4c8232dc 100644
--- a/src/cpu.rs
+++ b/src/cpu.rs
@@ -327,6 +327,11 @@ impl Cpu {
self.mmu().ppu()
}
+ #[inline(always)]
+ pub fn ppu_i(&self) -> &Ppu {
+ self.mmu_i().ppu_i()
+ }
+
#[inline(always)]
pub fn apu(&mut self) -> &mut Apu {
self.mmu().apu()
diff --git a/src/gb.rs b/src/gb.rs
index 7339d0e4..f0990106 100644
--- a/src/gb.rs
+++ b/src/gb.rs
@@ -105,6 +105,13 @@ impl GameBoySpeed {
}
}
+ pub fn multiplier(&self) -> u8 {
+ match self {
+ GameBoySpeed::Normal => 1,
+ GameBoySpeed::Double => 2,
+ }
+ }
+
pub fn from_u8(value: u8) -> GameBoySpeed {
match value {
0 => GameBoySpeed::Normal,
@@ -385,11 +392,12 @@ impl GameBoy {
pub fn clock(&mut self) -> u8 {
let cycles = self.cpu_clock();
+ let cycles_n = cycles / self.mmu().speed.multiplier();
if self.ppu_enabled {
- self.ppu_clock(cycles);
+ self.ppu_clock(cycles_n);
}
if self.apu_enabled {
- self.apu_clock(cycles);
+ self.apu_clock(cycles_n);
}
if self.dma_enabled {
self.dma_clock(cycles);
@@ -628,6 +636,10 @@ impl GameBoy {
self.mode == GameBoyMode::Sgb
}
+ pub fn speed(&self) -> GameBoySpeed {
+ self.mmu_i().speed
+ }
+
pub fn mode(&self) -> GameBoyMode {
self.mode
}
@@ -774,10 +786,18 @@ impl GameBoy {
self.cpu.mmu()
}
+ pub fn mmu_i(&self) -> &Mmu {
+ self.cpu.mmu_i()
+ }
+
pub fn ppu(&mut self) -> &mut Ppu {
self.cpu.ppu()
}
+ pub fn ppu_i(&self) -> &Ppu {
+ self.cpu.ppu_i()
+ }
+
pub fn apu(&mut self) -> &mut Apu {
self.cpu.apu()
}
diff --git a/src/mmu.rs b/src/mmu.rs
index bc7f82f3..9b9b792b 100644
--- a/src/mmu.rs
+++ b/src/mmu.rs
@@ -10,7 +10,6 @@ use crate::{
rom::Cartridge,
serial::Serial,
timer::Timer,
- warnln,
};
pub const BOOT_SIZE_DMG: usize = 256;
@@ -157,6 +156,10 @@ impl Mmu {
&mut self.ppu
}
+ pub fn ppu_i(&self) -> &Ppu {
+ &self.ppu
+ }
+
pub fn apu(&mut self) -> &mut Apu {
&mut self.apu
}
@@ -387,12 +390,6 @@ impl Mmu {
// 0xFF4D - KEY1: Speed switching (CGB only)
0x4d => {
- warnln!("Switching speed is not yet implemented");
-
- // @TODO: The switching of CPU speed is not yet
- // implemented and required more work to be done.
- // Inclusive the propagation of the speed to the
- // controller emulator.
self.switching = value & 0x01 == 0x01;
}
--
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