feat/savestates: Implement save/load state API for GameBoyAdvance

Using serde & bincode encoding


Former-commit-id: f5e4c599497f6bdf3096fa99f8b2d6ce89278ef7

src/core/arm7tdmi/arm/mod.rs

@@ -1,6 +1,8 @@
 pub mod display;
 pub mod exec;
 
+use serde::{Deserialize, Serialize};
+
 use super::alu::*;
 use crate::core::arm7tdmi::{Addr, InstructionDecoder, InstructionDecoderError};
 
@@ -38,7 +40,7 @@ impl ArmDecodeError {
     }
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Primitive)]
+#[derive(Serialize, Deserialize, Debug, Copy, Clone, PartialEq, Primitive)]
 pub enum ArmCond {
     EQ = 0b0000,
     NE = 0b0001,
@@ -57,7 +59,7 @@ pub enum ArmCond {
     AL = 0b1110,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq)]
+#[derive(Serialize, Deserialize, Debug, Copy, Clone, PartialEq)]
 #[allow(non_camel_case_types)]
 pub enum ArmFormat {
     /// Branch and Exchange
@@ -97,7 +99,7 @@ pub enum ArmHalfwordTransferType {
     SignedHalfwords = 0b11,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq)]
+#[derive(Serialize, Deserialize, Debug, Copy, Clone, PartialEq)]
 pub struct ArmInstruction {
     pub cond: ArmCond,
     pub fmt: ArmFormat,

src/core/arm7tdmi/cpu.rs

@@ -1,6 +1,7 @@
 use std::fmt;
 
 use ansi_term::{Colour, Style};
+use serde::{Deserialize, Serialize};
 
 pub use super::exception::Exception;
 use super::{
@@ -13,7 +14,7 @@ use crate::core::sysbus::{
     MemoryAccess, MemoryAccessType, MemoryAccessType::*, MemoryAccessWidth::*, SysBus,
 };
 
-#[derive(Debug, PartialEq)]
+#[derive(Serialize, Deserialize, Clone, Copy, Debug, PartialEq)]
 pub enum PipelineState {
     Refill1,
     Refill2,
@@ -26,7 +27,7 @@ impl Default for PipelineState {
     }
 }
 
-#[derive(Debug, Default)]
+#[derive(Serialize, Deserialize, Clone, Debug, Default)]
 pub struct Core {
     pub pc: u32,
     pub gpr: [u32; 15],

src/core/arm7tdmi/mod.rs

@@ -1,6 +1,7 @@
 use std::fmt;
 
 use num::Num;
+use serde::{Deserialize, Serialize};
 
 pub mod arm;
 pub mod thumb;
@@ -21,7 +22,7 @@ pub const REG_SP: usize = 13;
 
 pub(self) use crate::core::{Addr, Bus};
 
-#[derive(Debug, PartialEq, Copy, Clone)]
+#[derive(Serialize, Deserialize, Debug, PartialEq, Copy, Clone)]
 pub enum DecodedInstruction {
     Arm(ArmInstruction),
     Thumb(ThumbInstruction),

src/core/arm7tdmi/psr.rs

@@ -1,6 +1,8 @@
 /// The program status register
 use std::fmt;
 
+use serde::{Deserialize, Serialize};
+
 use crate::bit::BitIndex;
 use crate::num::FromPrimitive;
 
@@ -27,7 +29,7 @@ impl From<bool> for CpuState {
     }
 }
 
-#[derive(Debug, Clone, Copy, Default)]
+#[derive(Serialize, Deserialize, Debug, Clone, Copy, Default)]
 pub struct RegPSR {
     raw: u32,
 }

src/core/arm7tdmi/thumb/mod.rs

@@ -35,7 +35,7 @@ impl ThumbDecodeError {
     }
 }
 
-#[derive(Debug, Copy, Clone, PartialEq)]
+#[derive(Serialize, Deserialize, Debug, Copy, Clone, PartialEq)]
 pub enum ThumbFormat {
     /// Format 1
     MoveShiftedReg,
@@ -77,7 +77,7 @@ pub enum ThumbFormat {
     BranchLongWithLink,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq)]
+#[derive(Serialize, Deserialize, Debug, Copy, Clone, PartialEq)]
 pub struct ThumbInstruction {
     pub fmt: ThumbFormat,
     pub raw: u16,

src/core/cartridge.rs

@@ -4,6 +4,8 @@ use std::io::prelude::*;
 use std::path::Path;
 use std::str::from_utf8;
 
+use serde::{Deserialize, Serialize};
+
 use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
 use zip::ZipArchive;
 
@@ -35,7 +37,7 @@ use super::{Addr, Bus, GBAResult};
 ///   0C6h    26    Not used         (seems to be unused)
 ///   0E0h    4     JOYBUS Entry Pt. (32bit ARM branch opcode, eg. "B joy_start")
 ///
-#[derive(Debug)]
+#[derive(Serialize, Deserialize, Clone, Debug)]
 pub struct CartridgeHeader {
     // rom_entry_point: Addr,
     game_title: String,
@@ -69,7 +71,7 @@ impl CartridgeHeader {
     }
 }
 
-#[derive(Debug)]
+#[derive(Serialize, Deserialize, Clone, Debug)]
 pub struct Cartridge {
     pub header: CartridgeHeader,
     bytes: Box<[u8]>,

src/core/dma.rs

@@ -2,16 +2,10 @@ use super::iodev::consts::{REG_FIFO_A, REG_FIFO_B};
 use super::sysbus::SysBus;
 use super::{Addr, Bus, Interrupt, IrqBitmask};
 
-use bit_set::BitSet;
 use num::FromPrimitive;
+use serde::{Deserialize, Serialize};
 
-#[derive(Debug)]
-enum DmaTransferType {
-    Xfer16bit,
-    Xfer32bit,
-}
-
-#[derive(Debug)]
+#[derive(Serialize, Deserialize, Clone, Debug)]
 pub struct DmaChannel {
     id: usize,
 
@@ -30,7 +24,7 @@ pub struct DmaChannel {
     irq: Interrupt,
 }
 
-#[derive(Debug, Default)]
+#[derive(Serialize, Deserialize, Clone, Debug, Default)]
 struct DmaInternalRegs {
     src_addr: u32,
     dst_addr: u32,
@@ -172,10 +166,10 @@ impl DmaChannel {
     }
 }
 
-#[derive(Debug)]
+#[derive(Serialize, Deserialize, Clone, Debug)]
 pub struct DmaController {
     pub channels: [DmaChannel; 4],
-    pending_set: BitSet,
+    pending_set: u8,
     cycles: usize,
 }
 
@@ -188,20 +182,22 @@ impl DmaController {
                 DmaChannel::new(2),
                 DmaChannel::new(3),
             ],
-            pending_set: BitSet::with_capacity(4),
+            pending_set: 0,
             cycles: 0,
         }
     }
 
     pub fn is_active(&self) -> bool {
-        !self.pending_set.is_empty()
+        self.pending_set != 0
     }
 
     pub fn perform_work(&mut self, sb: &mut SysBus, irqs: &mut IrqBitmask) {
-        for id in self.pending_set.iter() {
-            self.channels[id].xfer(sb, irqs);
+        for id in 0..4 {
+            if self.pending_set & (1 << id) != 0 {
+                self.channels[id].xfer(sb, irqs);
+            }
         }
-        self.pending_set.clear();
+        self.pending_set = 0;
     }
 
     pub fn write_16(&mut self, channel_id: usize, ofs: u32, value: u16) {
@@ -213,9 +209,9 @@ impl DmaController {
             8 => self.channels[channel_id].write_word_count(value),
             10 => {
                 if self.channels[channel_id].write_dma_ctrl(value) {
-                    self.pending_set.insert(channel_id);
+                    self.pending_set |= 1 << channel_id;
                 } else {
-                    self.pending_set.remove(channel_id);
+                    self.pending_set &= !(1 << channel_id);
                 }
             }
             _ => panic!("Invalid dma offset {:x}", ofs),
@@ -225,7 +221,7 @@ impl DmaController {
     pub fn notify_vblank(&mut self) {
         for i in 0..4 {
             if self.channels[i].ctrl.is_enabled() && self.channels[i].ctrl.timing() == 1 {
-                self.pending_set.insert(i);
+                self.pending_set |= 1 << i;
             }
         }
     }
@@ -233,7 +229,7 @@ impl DmaController {
     pub fn notify_hblank(&mut self) {
         for i in 0..4 {
             if self.channels[i].ctrl.is_enabled() && self.channels[i].ctrl.timing() == 2 {
-                self.pending_set.insert(i);
+                self.pending_set |= 1 << i;
             }
         }
     }
@@ -245,14 +241,14 @@ impl DmaController {
                 && self.channels[i].ctrl.timing() == 3
                 && self.channels[i].dst == fifo_addr
             {
-                self.pending_set.insert(i);
+                self.pending_set |= 1 << i;
             }
         }
     }
 }
 
 bitfield! {
-    #[derive(Default)]
+    #[derive(Serialize, Deserialize, Clone, Default)]
     pub struct DmaChannelCtrl(u16);
     impl Debug;
     u16;

src/core/gba.rs

@@ -2,6 +2,9 @@
 use std::cell::RefCell;
 use std::rc::Rc;
 
+use bincode;
+use serde::{Deserialize, Serialize};
+
 use super::arm7tdmi::Core;
 use super::cartridge::Cartridge;
 use super::gpu::*;
@@ -23,6 +26,12 @@ pub struct GameBoyAdvance {
     cycles_to_next_event: usize,
 }
 
+#[derive(Serialize, Deserialize)]
+struct SaveState {
+    sysbus: Box<SysBus>,
+    cpu: Core,
+}
+
 impl GameBoyAdvance {
     pub fn new(
         cpu: Core,
@@ -49,6 +58,25 @@ impl GameBoyAdvance {
         }
     }
 
+    pub fn save_state(&self) -> bincode::Result<Vec<u8>> {
+        let s = SaveState {
+            cpu: self.cpu.clone(),
+            sysbus: self.sysbus.clone(),
+        };
+
+        bincode::serialize(&s)
+    }
+
+    pub fn restore_state(&mut self, bytes: &[u8]) -> bincode::Result<()> {
+        let decoded: Box<SaveState> = bincode::deserialize_from(bytes)?;
+
+        self.cpu = decoded.cpu;
+        self.sysbus = decoded.sysbus;
+        self.cycles_to_next_event = 1;
+
+        Ok(())
+    }
+
     #[inline]
     pub fn key_poll(&mut self) {
         self.sysbus.io.keyinput = self.input_device.borrow_mut().poll();

src/core/gpu/mod.rs

@@ -2,6 +2,8 @@ use std::cell::RefCell;
 use std::fmt;
 use std::rc::Rc;
 
+use serde::{Deserialize, Serialize};
+
 use super::super::VideoInterface;
 use super::interrupt::IrqBitmask;
 use super::sysbus::{BoxedMemory, SysBus};
@@ -50,7 +52,7 @@ pub enum PixelFormat {
     BPP8 = 1,
 }
 
-#[derive(Debug, PartialEq, Copy, Clone)]
+#[derive(Serialize, Deserialize, Debug, PartialEq, Copy, Clone)]
 pub enum GpuState {
     HDraw = 0,
     HBlank,
@@ -95,7 +97,7 @@ impl std::ops::IndexMut<usize> for Scanline {
     }
 }
 
-#[derive(Debug, Default, Copy, Clone)]
+#[derive(Serialize, Deserialize, Debug, Default, Clone)]
 pub struct Background {
     pub bgcnt: BgControl,
     pub bgvofs: u16,
@@ -107,7 +109,7 @@ pub struct Background {
     mosaic_first_row: Scanline,
 }
 
-#[derive(Debug, Default)]
+#[derive(Serialize, Deserialize, Clone, Debug, Default)]
 pub struct Window {
     pub left: u8,
     pub right: u8,
@@ -151,7 +153,7 @@ pub struct AffineMatrix {
     pub pd: i32,
 }
 
-#[derive(Debug, Default, Copy, Clone)]
+#[derive(Serialize, Deserialize, Debug, Default, Copy, Clone)]
 pub struct BgAffine {
     pub pa: i16, // dx
     pub pb: i16, // dmx
@@ -163,7 +165,7 @@ pub struct BgAffine {
     pub internal_y: i32,
 }
 
-#[derive(Debug, Copy, Clone)]
+#[derive(Serialize, Deserialize, Debug, Copy, Clone)]
 pub struct ObjBufferEntry {
     pub(super) color: Rgb15,
     pub(super) priority: u16,
@@ -182,7 +184,7 @@ impl Default for ObjBufferEntry {
 
 type VideoDeviceRcRefCell = Rc<RefCell<dyn VideoInterface>>;
 
-#[derive(DebugStub)]
+#[derive(Serialize, Deserialize, Clone, DebugStub)]
 pub struct Gpu {
     pub state: GpuState,
 

src/core/gpu/regs.rs

@@ -1,6 +1,8 @@
 use super::sfx::BldMode;
 use super::*;
 
+use serde::{Deserialize, Serialize};
+
 pub const SCREEN_BLOCK_SIZE: u32 = 0x800;
 
 #[derive(Debug, PartialEq)]
@@ -60,6 +62,7 @@ impl BgControl {
 
 // struct definitions below because the bitfield! macro messes up syntax highlighting in vscode.
 bitfield! {
+    #[derive(Serialize, Deserialize, Clone)]
     pub struct DisplayControl(u16);
     impl Debug;
     u16;
@@ -79,6 +82,7 @@ bitfield! {
 }
 
 bitfield! {
+    #[derive(Serialize, Deserialize, Clone)]
     pub struct DisplayStatus(u16);
     impl Debug;
     u16;
@@ -92,7 +96,7 @@ bitfield! {
 }
 
 bitfield! {
-    #[derive(Default, Copy, Clone)]
+    #[derive(Serialize, Deserialize, Default, Copy, Clone)]
     pub struct BgControl(u16);
     impl Debug;
     u16;
@@ -106,7 +110,7 @@ bitfield! {
 }
 
 bitfield! {
-    #[derive(Default, Copy, Clone)]
+    #[derive(Serialize, Deserialize, Default, Copy, Clone)]
     pub struct RegMosaic(u16);
     impl Debug;
     u32;
@@ -117,7 +121,7 @@ bitfield! {
 }
 
 bitflags! {
-    #[derive(Default)]
+    #[derive(Serialize, Deserialize, Default)]
     pub struct BlendFlags: u32 {
         const BG0 = 0b00000001;
         const BG1 = 0b00000010;
@@ -148,7 +152,7 @@ impl BlendFlags {
 }
 
 bitfield! {
-    #[derive(Default, Copy, Clone)]
+    #[derive(Serialize, Deserialize, Default, Copy, Clone)]
     pub struct BlendControl(u16);
     impl Debug;
     pub into BlendFlags, top, _: 5, 0;
@@ -157,7 +161,7 @@ bitfield! {
 }
 
 bitfield! {
-    #[derive(Default, Copy, Clone)]
+    #[derive(Serialize, Deserialize, Default, Copy, Clone)]
     pub struct BlendAlpha(u16);
     impl Debug;
     u16;
@@ -166,7 +170,7 @@ bitfield! {
 }
 
 bitflags! {
-    #[derive(Default)]
+    #[derive(Serialize, Deserialize, Default)]
     pub struct WindowFlags: u32 {
         const BG0 = 0b00000001;
         const BG1 = 0b00000010;
@@ -200,7 +204,7 @@ const BG_WIN_FLAG: [WindowFlags; 4] = [
 ];
 
 bitfield! {
-    #[derive(Default, Copy, Clone)]
+    #[derive(Serialize, Deserialize, Default, Copy, Clone)]
     pub struct WindowReg(u16);
     impl Debug;
     u16;

src/core/gpu/rgb15.rs

@@ -1,8 +1,10 @@
 //! Helper type to deal with the GBA's 15bit color
 
+use serde::{Deserialize, Serialize};
+
 bitfield! {
     #[repr(transparent)]
-    #[derive(Copy, Clone, Default, PartialEq)]
+    #[derive(Serialize, Deserialize, Copy, Clone, Default, PartialEq)]
     pub struct Rgb15(u16);
     impl Debug;
     pub r, set_r: 4, 0;

src/core/interrupt.rs

@@ -1,4 +1,6 @@
-#[derive(Debug, Primitive, Copy, Clone, PartialEq)]
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize, Debug, Primitive, Copy, Clone, PartialEq)]
 #[allow(non_camel_case_types)]
 pub enum Interrupt {
     LCD_VBlank = 0,
@@ -17,7 +19,7 @@ pub enum Interrupt {
     GamePak = 13,
 }
 
-#[derive(Debug, Default)]
+#[derive(Serialize, Deserialize, Clone, Debug, Default)]
 pub struct InterruptController {
     pub interrupt_master_enable: bool,
     pub interrupt_enable: IrqBitmask,
@@ -48,7 +50,7 @@ impl IrqBitmask {
 }
 
 bitfield! {
-    #[derive(Default, Copy, Clone, PartialEq)]
+    #[derive(Serialize, Deserialize, Default, Copy, Clone, PartialEq)]
     pub struct IrqBitmask(u16);
     impl Debug;
     u16;

src/core/iodev.rs

@@ -7,15 +7,18 @@ use super::sound::SoundController;
 use super::timer::Timers;
 use super::{Addr, Bus};
 
+use serde::{Deserialize, Serialize};
+
 use self::consts::*;
 
-#[derive(Debug, Clone, Copy, PartialEq)]
+#[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq)]
 pub enum HaltState {
     Running,
     Halt, // In Halt mode, the CPU is paused as long as (IE AND IF)=0,
     Stop, // In Stop mode, most of the hardware including sound and video are paused
 }
 
+#[derive(Clone, Serialize, Deserialize)]
 pub struct IoDevices {
     pub intc: InterruptController,
     pub gpu: Box<Gpu>,
@@ -262,7 +265,7 @@ impl Bus for IoDevices {
 }
 
 bitfield! {
-    #[derive(Default, Copy, Clone, PartialEq)]
+    #[derive(Serialize, Deserialize, Default, Copy, Clone, PartialEq)]
     pub struct WaitControl(u16);
     impl Debug;
     u16;

src/core/sound/dsp.rs

@@ -1,12 +1,14 @@
 use crate::{AudioInterface, StereoSample};
 
+use serde::{Deserialize, Serialize};
+
 const PI: f32 = std::f32::consts::PI;
 
 pub trait Resampler {
     fn push_sample(&mut self, s: StereoSample, audio: &mut dyn AudioInterface);
 }
 
-#[derive(Debug)]
+#[derive(Serialize, Deserialize, Clone, Debug)]
 pub struct CosineResampler {
     last_in_sample: StereoSample,
     phase: f32,

src/core/sound/fifo.rs

@@ -1,7 +1,9 @@
 // TODO write tests or replace with a crate
 const SOUND_FIFO_CAPACITY: usize = 32;
 
-#[derive(Debug)]
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize, Clone, Debug)]
 pub struct SoundFifo {
     wr_pos: usize,
     rd_pos: usize,

src/core/sound/mod.rs

@@ -2,6 +2,7 @@ use std::cell::RefCell;
 use std::rc::Rc;
 
 use bit::BitIndex;
+use serde::{Deserialize, Serialize};
 
 use super::dma::DmaController;
 use super::iodev::consts::*;
@@ -18,10 +19,7 @@ const DMG_RATIOS: [f32; 4] = [0.25, 0.5, 1.0, 0.0];
 const DMA_TIMERS: [usize; 2] = [0, 1];
 const DUTY_RATIOS: [f32; 4] = [0.125, 0.25, 0.5, 0.75];
 
-#[derive(Debug)]
-struct NoiseChannel {}
-
-#[derive(Debug)]
+#[derive(Serialize, Deserialize, Clone, Debug)]
 struct DmaSoundChannel {
     value: i8,
     volume_shift: i16,
@@ -62,7 +60,7 @@ const REG_FIFO_B_H: u32 = REG_FIFO_B + 2;
 
 type AudioDeviceRcRefCell = Rc<RefCell<dyn AudioInterface>>;
 
-#[derive(DebugStub)]
+#[derive(Serialize, Deserialize, Clone, Debug)]
 pub struct SoundController {
     sample_rate_to_cpu_freq: usize, // how many "cycles" are a sample?
     cycles: usize,                  // cycles count when we last provided a new sample.

src/core/sysbus.rs

@@ -1,6 +1,8 @@
 use std::fmt;
 use std::ops::Add;
 
+use serde::{Deserialize, Serialize};
+
 use super::cartridge::Cartridge;
 use super::gpu::{GpuState, VIDEO_RAM_SIZE};
 use super::iodev::IoDevices;
@@ -64,7 +66,7 @@ impl fmt::Display for MemoryAccess {
     }
 }
 
-#[derive(Debug)]
+#[derive(Serialize, Deserialize, Clone, Debug)]
 pub struct BoxedMemory {
     pub mem: Box<[u8]>,
 }
@@ -77,15 +79,17 @@ impl BoxedMemory {
 
 impl Bus for BoxedMemory {
     fn read_8(&self, addr: Addr) -> u8 {
-        self.mem[addr as usize]
+        unsafe { *self.mem.get_unchecked(addr as usize) }
     }
 
     fn write_8(&mut self, addr: Addr, value: u8) {
-        self.mem[addr as usize] = value;
+        unsafe {
+            *self.mem.get_unchecked_mut(addr as usize) = value;
+        }
     }
 }
 
-#[derive(Debug)]
+#[derive(Serialize, Deserialize, Clone, Debug)]
 struct DummyBus([u8; 4]);
 
 impl Bus for DummyBus {
@@ -96,6 +100,7 @@ impl Bus for DummyBus {
     fn write_8(&mut self, _addr: Addr, _value: u8) {}
 }
 
+#[derive(Serialize, Deserialize, Clone)]
 pub struct SysBus {
     pub io: IoDevices,
 

src/core/timer.rs

@@ -2,11 +2,10 @@ use super::interrupt::{Interrupt, IrqBitmask};
 use super::iodev::consts::*;
 use super::sysbus::SysBus;
 
-use bit_set::BitSet;
-
 use num::FromPrimitive;
+use serde::{Deserialize, Serialize};
 
-#[derive(Debug)]
+#[derive(Serialize, Deserialize, Clone, Debug)]
 pub struct Timer {
     // registers
     pub ctl: TimerCtl,
@@ -66,10 +65,10 @@ impl Timer {
     }
 }
 
-#[derive(Debug)]
+#[derive(Serialize, Deserialize, Clone, Debug)]
 pub struct Timers {
     timers: [Timer; 4],
-    running_timers: BitSet,
+    running_timers: u8,
     pub trace: bool,
 }
 
@@ -90,7 +89,7 @@ impl Timers {
     pub fn new() -> Timers {
         Timers {
             timers: [Timer::new(0), Timer::new(1), Timer::new(2), Timer::new(3)],
-            running_timers: BitSet::with_capacity(4),
+            running_timers: 0,
             trace: false,
         }
     }
@@ -101,9 +100,9 @@ impl Timers {
         let new_enabled = self[id].ctl.enabled();
         let cascade = self.timers[id].ctl.cascade();
         if new_enabled && !cascade {
-            self.running_timers.insert(id);
+            self.running_timers |= 1 << id;
         } else {
-            self.running_timers.remove(id);
+            self.running_timers &= !(1 << id);
         }
         if self.trace && old_enabled != new_enabled {
             println!(
@@ -158,7 +157,11 @@ impl Timers {
     }
 
     pub fn update(&mut self, cycles: usize, sb: &mut SysBus, irqs: &mut IrqBitmask) {
-        for id in self.running_timers.iter() {
+        for id in 0..4 {
+            if self.running_timers & (1 << id) == 0 {
+                continue;
+            }
+
             if !self.timers[id].ctl.cascade() {
                 let timer = &mut self.timers[id];
                 let num_overflows = timer.update(cycles, irqs);
@@ -181,7 +184,7 @@ impl Timers {
 }
 
 bitfield! {
-    #[derive(Default)]
+    #[derive(Serialize, Deserialize, Clone, Default)]
     pub struct TimerCtl(u16);
     impl Debug;
     u16;