spieglt / nestur Goto Github PK

The NES (emulator) you left outside in the rain but let dry and still kind of works

Rust 100.00%

emulator nes rust sdl2

nestur's Introduction

nestur

Nestur is an NES emulator. There are plenty of full-featured emulators out there; this is primarily an educational project but it is usable. There may still be many bugs, but I'm probably not aware of them so please submit issues.

no use of unsafe
NTSC timing
supports mappers 0-4 which cover ~85% of games

The code aims to follow the explanations from the NES dev wiki where possible, especially in the PPU, and the comments quote from it often. Thanks to everyone who contributes to that wiki/forum, and to Michael Fogleman's NES and Scott Ferguson's Fergulator for getting me unstuck at several points.

Controls

 Button  |   Key
___________________
|   A    |    D   |
|   B    |    F   |
| Start  |  Enter |
| Select | R-Shift|
|   Up   |   Up   |
|  Down  |  Down  |
|  Left  |  Left  |
|  Right |  Right |
-------------------

F2: reset console
F5: save game state
F9: load most recent save state

If the game is called mygame.nes, the save state files will be called mygame-#.dat. To load any previous save state, drag and drop a .dat file onto the window.

Use

Double-click or run the executable from a terminal by itself to launch with instructions. Then click Ok and drag a (iNES/.nes) ROM file onto the window. Or, drag and drop a ROM file onto the executable to run it directly, or use the path to the ROM file as the first argument to the terminal command.

If the game uses battery-backed RAM (if it can save data when the console is turned off), a save file like rom_filename.sav will be created in the same folder as the ROM when the program is exited. When Nestur is run again, it will look for a file matching the ROM name, with a .sav extension instead of .nes.

Compilation

Install Rust
Have a C compiler
- Linux: sudo apt install build-essential
- Mac: XCode
- Windows: install the Visual Studio Build Tools (or Visual Studio with the "Desktop development with C++" workload).
Install CMake
- Linux: sudo apt install cmake
- Mac: install Homebrew and run brew install cmake
- Windows
cd nestur/ && cargo build --release (be sure to build/run with the release flag or it will run very slowly)
The nestur executable or nestur.exe will be in nestur/target/release.

To do

support other controllers?
more mappers?
better save file organization?

Known problem games

None currently, please report any issues

Please also check out Cloaker and Flying Carpet!

nestur's People

Contributors

Stargazers

Watchers

Forkers

triptych diegopacheco bitemyapp sekmet happy-ferret jacke atul9 zmilan cloudified-intelligence maslabgamer acalhoon geekhuyang heinrichsmythe adityavmonga michaelfaster gg-big-org iq-scm

nestur's Issues

Emulation Timing Issues and Sprite Zero Hit Inaccuracies

Hi!

I spent some time last night diving into some nes test roms for my fuzzer, and uncovered the following small issues. With these issues fixed games like Mega Man reproduce much better (although there are still some NMI timing issues I have yet to look into)

Given https://github.com/christopherpow/nes-test-roms/tree/master/cpu_timing_test6 the following opcodes report inaccuracies:

JMP in ABS mode (1 cycle too long)
RTI (2 cycles too long)
STA in Indirect Indexed Mode (should be 6)
STA in Absolute Y mode (should be 5)

I've fixed this in my fuzzer by adding offsets to JMP and RTI, and adding a before_clock parameter to report a complete offset for STA in those 2 special cases (see: https://git.openprivacy.ca/sarah/nesfuzz/commit/f7110dcd50da9680d79d7253c436989818c39609) - but this is kinda hacky and you may or may not want to use a different approach.

Given https://github.com/christopherpow/nes-test-roms/tree/master/sprite_hit_tests_2005.10.05

06.right_edge fails (Should always miss when X = 255) - can be fixed with a check in src/ppu/rendering.rs
07.screen_bottom ( Should always miss when Y = 255) - this seems to be related to PPU timing issues.

Note: 09/10/11 will all fail until cpu cycle issues documented above are fixed.

Given https://github.com/christopherpow/nes-test-roms/tree/master/blargg_ppu_tests_2005.09.15b

cpu writes to 0x4014, OAMDATA should start at the address in OAMADDR and wrap rather than replace OAM entirely.

Attempt to subtract with overflow

Nice project! I found a problem and thought you might want this bug report. This is based on commit
ea70b59. I'm a little new to Rust so I can't help much with the diagnosis.

fps: 14
fps: 9
thread 'main' panicked at 'attempt to subtract with overflow', src/apu/square.rs:117:17
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.37/src/backtrace/libunwind.rs:88
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.37/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:76
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:60
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1030
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1412
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:64
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:196
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:210
  10: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:473
  11: std::panicking::continue_panic_fmt
             at src/libstd/panicking.rs:380
  12: rust_begin_unwind
             at src/libstd/panicking.rs:307
  13: core::panicking::panic_fmt
             at src/libcore/panicking.rs:85
  14: core::panicking::panic
             at src/libcore/panicking.rs:49
  15: nestur::apu::square::Square::calculate_target_period
             at src/apu/square.rs:117
  16: nestur::apu::square::Square::write_timer_low
             at src/apu/square.rs:146
  17: nestur::apu::Apu::write_reg
             at src/apu/mod.rs:95
  18: nestur::cpu::Cpu::write
             at src/cpu/mod.rs:203
  19: nestur::cpu::opcodes::<impl nestur::cpu::Cpu>::stx
             at src/cpu/opcodes.rs:491
  20: nestur::cpu::Cpu::step
             at src/cpu/mod.rs:174
  21: nestur::main
             at src/main.rs:58
  22: std::rt::lang_start::{{closure}}
             at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/rt.rs:64
  23: std::rt::lang_start_internal::{{closure}}
             at src/libstd/rt.rs:49
  24: std::panicking::try::do_call
             at src/libstd/panicking.rs:292
  25: __rust_maybe_catch_panic
             at src/libpanic_unwind/lib.rs:80
  26: std::panicking::try
             at src/libstd/panicking.rs:271
  27: std::panic::catch_unwind
             at src/libstd/panic.rs:394
  28: std::rt::lang_start_internal
             at src/libstd/rt.rs:48
  29: std::rt::lang_start
             at /rustc/4560ea788cb760f0a34127156c78e2552949f734/src/libstd/rt.rs:64
  30: main
  31: __libc_start_main
  32: _start
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

spieglt / nestur Goto Github PK

nestur's Introduction

nestur

Controls

Use

Compilation

To do

Known problem games

nestur's People

Contributors

Stargazers

Watchers

Forkers

nestur's Issues

Emulation Timing Issues and Sprite Zero Hit Inaccuracies

Attempt to subtract with overflow

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