nes-sim 0.1.4

A NES (Famicom) emulator core library written in pure Rust.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145

use crate::{
    AudioBatch, CartridgeError, ControllerState, CoreCommand, DebugSnapshot, NES, SaveStateError,
    VideoFrame,
};

#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct FrontendInput {
    pub controller1: ControllerState,
    pub controller2: ControllerState,
    pub reset: bool,
    pub toggle_pause: bool,
    pub step_frame: bool,
    pub step_cpu_instruction: bool,
    pub quit: bool,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum RunMode {
    Running,
    Paused,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum ExecutionTarget {
    None,
    Frame,
    CpuInstruction,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct RuntimeStatus {
    pub mode: RunMode,
    pub executed: ExecutionTarget,
    pub quit_requested: bool,
}

#[derive(Clone, Copy, Debug)]
pub struct RuntimeSnapshot<'a> {
    pub status: RuntimeStatus,
    pub video: VideoFrame<'a>,
    pub audio: AudioBatch<'a>,
    pub debug: DebugSnapshot,
}

pub struct FrontendRuntime {
    nes: NES,
    mode: RunMode,
}

impl FrontendRuntime {
    pub fn new(nes: NES) -> Self {
        Self {
            nes,
            mode: RunMode::Running,
        }
    }

    pub fn from_rom_bytes(rom: &[u8]) -> Result<Self, CartridgeError> {
        let mut nes = NES::new();
        nes.load_cartridge_ines(rom)?;
        nes.reset();
        Ok(Self::new(nes))
    }

    pub fn mode(&self) -> RunMode {
        self.mode
    }

    pub fn nes(&self) -> &NES {
        &self.nes
    }

    pub fn nes_mut(&mut self) -> &mut NES {
        &mut self.nes
    }

    pub fn save_state(&self) -> Result<Vec<u8>, SaveStateError> {
        self.nes.save_state()
    }

    pub fn load_state(&mut self, bytes: &[u8]) -> Result<(), SaveStateError> {
        self.nes.load_state(bytes)
    }

    pub fn set_mode(&mut self, mode: RunMode) {
        self.mode = mode;
    }

    pub fn snapshot(&self) -> RuntimeSnapshot<'_> {
        RuntimeSnapshot {
            status: RuntimeStatus {
                mode: self.mode,
                executed: ExecutionTarget::None,
                quit_requested: false,
            },
            video: self.nes.video_frame(),
            audio: self.nes.audio_batch(),
            debug: self.nes.debug_snapshot(),
        }
    }

    pub fn step(&mut self, input: FrontendInput) -> RuntimeSnapshot<'_> {
        self.nes.clear_audio_samples();
        self.nes.execute(CoreCommand::SetControllerState {
            port: 0,
            state: input.controller1,
        });
        self.nes.execute(CoreCommand::SetControllerState {
            port: 1,
            state: input.controller2,
        });

        if input.reset {
            self.nes.execute(CoreCommand::Reset);
        }

        if input.toggle_pause {
            self.mode = match self.mode {
                RunMode::Running => RunMode::Paused,
                RunMode::Paused => RunMode::Running,
            };
        }

        let executed = if input.step_cpu_instruction {
            self.nes.execute(CoreCommand::StepCpuInstruction);
            ExecutionTarget::CpuInstruction
        } else if input.step_frame || matches!(self.mode, RunMode::Running) {
            self.nes.execute(CoreCommand::RunFrame);
            ExecutionTarget::Frame
        } else {
            ExecutionTarget::None
        };

        RuntimeSnapshot {
            status: RuntimeStatus {
                mode: self.mode,
                executed,
                quit_requested: input.quit,
            },
            video: self.nes.video_frame(),
            audio: self.nes.audio_batch(),
            debug: self.nes.debug_snapshot(),
        }
    }
}