DyNES, a dynamically-recompiling NES

An extensible, dynamically recompiling NES emulator. As study on how to build it. May also serve as sample how to architecture a project like this.

Written in C++ using Qt5 for GUI.

Building

You can open the Dynes.pro in the QtCreator IDE, or run these commands:

# Create a build directory
mkdir build
cd build

# Run QMake
qmake ..

# Build
make -j$(nproc)

Configuration

You can enable specific CPU cores at build-time by supplying the name to qmake like so: qmake .. "CONFIG+=dynes_core_lua". Repeat the CONIFG argument for multiple cores.

CPU cores

Right now, there are four to choose from:

Interpret

Standard interpret. While a modern computer will have no issues running it at full speed, it's not optimized for speed. It's pretty simple however.

Built-in and can't be disabled.

AMD64 Dynarec

Fully self-contained AMD64 dynarec. Only works on AMD64 (x86_64) machines.

Requires Nothing.

Config option is dynes_core_dynarec_amd64

LLVM Dynarec

A LLVM-based dynamic recompiler. Uses LLVM to dynamically recompile code from 6502 machine code to LLVM bytecode, and then using a JIT, to what the host platform uses.

Requires LLVM 4.0

Config option is dynes_core_dynarec_llvm (Disabled by default)

It is possible to use this core with LLVM versions 5.0 and 6.0 when using a debug-build instead of a release-build: qmake .. "CONFIG+=debug" ....

Lua Dynarec

An experiment what happens if you use Lua (A simple yet fully-featured scripting language) as run-time. Dynamically recompiles from 6502 machine code to Lua script, and then calls it. It offers surprisingly good performance.

Requires Lua version 5.3 or LuaJit

Config option is dynes_core_lua (Disabled by default)

Cartridge mappers

Only NROM and MMC1 are supported.

Testing

Tests are done by using test ROMs, which can be automatically ran an verified on all (compiled) CPU cores. These automatic verifications are called "casettes", and reside in test/casettes.

How to run

Build the project like shown above. Then run the test binary, supplying it with the paths to the casette files. All casettes will be ran against all CPU cores.

# Make use of your shells path expansion feature to run all casettes:
$ build/test/test test/casettes/*.conf

Casette files

Casette configuration files end in .conf and are text- and line-based. Each line describes a command to execute. Command names and arguments are case-insensitive, except for path names. Commands and arguments are separated by one (or multiple) horizontal space(s). The end of a line marks the end of a command.

Commands accepting a path name will resolve it relative to the current casette file.

Empty lines, and lines beginning with #, are ignored.

# This is ignored.
   # As is this, and the following empty line too:

# Comments MUST start at the beginning, the following will NOT work:
OPEN foo.nes  # Some comment.

In syntax descriptions <x> means that x is a mandatory argument and [x] is an optional argument. The brackets are not to be written and only serve explanatory purposes in this document. A ... means that the previous argument can be repeated as often as you want. A pipe (|), like in [x|y], means that either x or y are expected. Full upper-cased [KEY|WORDS] mean that one of the keywords is expected, otherwise it's a free-form argument.

Commands

ONFAIL sets a custom message to be shown if the following command fails. If the following command succeeds, the message is discarded.

Syntax: ONFAIL <Message>

OPEN opens a .nes ROM. Expects the path to the ROM file as argument.

Syntax: OPEN <Path to .nes>

ONFAIL Uses the test by foobar, download from http://example.com
OPEN foobar.nes

ADVANCE advances the emulator by one or more frames. Optionally, one or more buttons can be pressed. These will be held down during the whole duration of the command, and will be released afterwards.

Syntax: ADVANCE [Count of frames, defaults to 1] [UP|DOWN|LEFT|RIGHT|A|B|START|SELECT] ...

# Advances one frame:
ADVANCE

# Advances 60 frames (= one second):
ADVANCE 60

# Advances one frame with LEFT+A pressed:
ADVANCE LEFT A

# Advances 10 frames while pressing START+DOWN
ADVANCE 10 START DOWN

FRAME saves the current displayed framebuffer as .bmp file onto the disk. The file name can contain a % which will be replaced by the name of the current core. This command can be used to generate the pictures for a COMPARE.

Syntax: FRAME <FileName.bmp>

# Stores the current frame into foo.bmp.  If ran with multiple cores they'll
# override each others file!
FRAME foo.bmp

# Stores the current frame into "foo_%.bmp", where "%" will be replaced by the
# current core's name.  May produce "foo_interpret.bmp" and "foo_amd64.bmp".
FRAME foo_%.bmp

COMPARE compares the current displayed framebuffer with a given .bmp file. The file name can also contain %, and works just like in FRAME. This command is best used with a FRAME preceeding it to ease debugging output issues.

Syntax: COMPARE <FileName.bmp>

# Compares the current frame with foo.bmp:
COMPARE foo.bmp

# Compares the current frame with foo_interpret.bmp, foo_amd64.bmp, etc.
COMPARE foo_%.bmp

Missing

• Sound
• More cartridge mappers

License

This project is licensed under the GPLv3.