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153 lines
4.8 KiB
Markdown
153 lines
4.8 KiB
Markdown
[]
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(https://travis-ci.org/simias/rustation)
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# Rustation PlayStation emulator
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PlayStation emulator in the Rust programing language.
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The focus of this emulator is to write code that's clean, accurate and
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hopefully easy to understand. There's no plugin infrastructure, the
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emulator is monolithic.
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Performance is pretty poor but it should be enough to run close to
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realtime on a modern CPU (there's no framelimiting implemented at the
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moment).
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The current frontend code is built around SDL2. The plan once the
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emulator starts to become usable is to turn it into a libretro core so
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that it could be played in
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[RetroArch](https://github.com/libretro/RetroArch) for instance.
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For the time being it can only boot a few games. Crash Bandicoot
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(Japanese version) is mostly playable, although I've had random
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crashes. Some other games (like Spyro) freeze after or during the
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intro.
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The GPU rendering is implemented using OpenGL through the [glium
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API](https://github.com/tomaka/glium), the idea is to allow things
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like increased internal resolution, texture replacement and other
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enhancements down the line. Using modern OpenGL it should be possible
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to write a flexible yet reasonably accurate renderer. At least that's
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the theory, there's quite a lot of work to do before it reaches a
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playable state.
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If you have any questions, in particular if something in the code is
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not clear or properly commented don't hesitate to fill an issue.
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I also created a [/psx/ board on 8chan](https://8ch.net/psx/) if you
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prefer something less formal to discuss this emulator and all things
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PlayStation. We'll see if this turns out to be a good idea...
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## Currently implemented (even partially)
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![Crash Bandicoot (Japan)]
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(https://raw.githubusercontent.com/wiki/simias/rustation/images/crash_bandicoot-level1.png)
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* CPU
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* Basic GTE support (ported from mednafen PSX)
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* Instruction cache
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* Interrupts
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* Very basic GPU (no textures)
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* Timers
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* DMA
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* Debugger
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* CDROM controller (missing many commands)
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* Gamepad controller (only digital pad for now)
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## Todo list
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* Most of the GPU
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* MDEC
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* SPU
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* Memory card
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* CPU pipeline emulation
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* More accurate timings
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* Many, many other things...
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## Build
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You'll need [Rust and its package manager Cargo]
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(https://www.rust-lang.org/),
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[SDL2](https://www.libsdl.org/download-2.0.php) and a PlayStation
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BIOS. The emulator is mainly tested with BIOS version `SCPH1001` whose
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SHA-1 is `10155d8d6e6e832d6ea66db9bc098321fb5e8ebf`.
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You should then be able to build the emulator with:
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```
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cargo build --release
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```
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Don't forget the `--release` flag in order to turn optimizations
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on. Without them the resulting binary will be absurdly slow.
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If the build is succesful you can run the emulator using:
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```
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cargo run --release /path/to/SCPH1001.BIN
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```
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For Windows check issue [#12](https://github.com/simias/rustation/issues/12).
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Use the `Escape` key to exit the emulator, `Pause/Break` to "break" into the
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debugger, the emulator will then listen on TCP port `9001` for a GDB
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connection.
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## Debugger
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In order to debug you'll need a GDB targetting
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`mipsel-unknown-elf`. Once the emulator is running press the
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`Pause/Break` key to trigger the debugger and then connect GDB to it
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using (at the gdb command prompt):
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`target remote localhost:9001`
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GDB might complain about not finding symbols or the boundaries of the
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current function but you can ignore that. From then you should be able
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to use the familiar [GDB commands]
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(https://sourceware.org/gdb/onlinedocs/gdb/) to debug the live
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emulator.
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A few examples:
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```
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# Dump the CPU registers
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info registers
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# Disassemble 20 instructions around PC
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disassemble $pc-40,+80
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# Display word at address 0x1f801814 (GPU status)
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x/x 0x1f801814
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# Add code breakpoint at address 0x00004588
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break *0x00004588
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# Add write watchpoint at address 0x1f801070 (IRQ ack)
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watch *0x1f801070
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# Step over a single instruction
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stepi
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# Continue until a break/watchpoint is reached (or Pause/Break is pressed)
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continue
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```
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The debugger support is pretty experimental and quircky but it works
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for basic debugging needs.
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## Guide
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I'm also attempting to document the emulator writing process in a
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LaTeX document available in the
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[psx-guide repository](https://github.com/simias/psx-guide). It's
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generally lagging behind the actual code but I'll try to update it as
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often as possible.
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## Resources
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I try to cite all of my sources in the guide above but I'm mainly
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using the priceless [No$ PSX
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specifications](http://problemkaputt.de/psx-spx.htm) as well as
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[mednafen](http://mednafen.fobby.net/)'s source code when I feel like
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cheating.
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I also run tests on the real hardware and store them in the
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[psx-hardware-tests repository]
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(https://github.com/simias/psx-hardware-tests/tree/master/tests).
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