This respository contains everything necessary to create a working RISC-V image of Project Oberon 2013, including a working RV32IM compiler as well as a port of Oberon itself.
Runtime/RISC5 emulator and operating system interface.Oberon/Unmodified source code from Project Oberon 2013.OberonRV/RISC-V modified source code.Norebo/Norebo-specific and new modules.Bootstrap/Pre-compiled modules to bootstrap Norebo.
If you don't want to figure out how to build an image, and you just want to try this out, clone the repository for the RISC-V Oberon emulator instead, as it includes an example RISC-V image.
To build a RISC-V image, simply run:
make imagervThis will deposit a disk image: imagebuild/Oberon.dsk. This can be used for the emulator.
If you wish more control over the process, here is how to generate one with a different manifest, from whichever folder you prefer:
rm -rf imagebuild
./build-image.py -r OberonRV/Oberon -m manifests/manifest.csvThe -r flag specifies the creation of a RISC-V image. By default, build-image will select the manifests/manifest.csv manifest; but there are a few other manifests in that folder, and you can use a -m flag to specify using them instead. Editing the manifest to include whichever files you wish to include should be fairly straight-forward; just remember to add the corresponding .Mod files in the OberonRV/Oberon folder. You can specify a different folder than OberonRV/Oberon, but an unedited PO2013 repository will not work without some significant changes.
The bootloader is embedded in the emulator. Thus, changing it is a separate process from building the image. You probably don't need to change the bootloader, but if you desire to:
- Compile your bootloader using the RISC-V compiler. To make this easier for yourself, running
cd OberonRV; source functions.shwill source therocandnorcommands. You can then runroc BootLoad.mod, and the compiled program can be found inBootLoad.rsc. - Use
ORX.Modin andreaspirklbauer'sOberon-building-tools, included as a submodule, to write a file that can be used as bootloader:nor ORX.WriteFile BootLoad.rsc BootLoad.code. BootLoad.code now contains a list of RISC-V instructions. - Currently, the emulator won't understand this format. You need to add
0xto the start of every line, and a comma to the end. You can look atsrc/emu/bootloader.incin the emulator for an example of the formatting. (I use vim to do this, and that's quick enough that I never bothered to write a script for it. So, this part is left as an exercise to the reader.) Then, replace bootloader.inc with your own bootloader.
- Test it on an FPGA; should be doable
- Support REALs and interrupts
- 64-bit support. This is rather easy, as to my knowledge it only requires minor changes.
- Bootstrap Norebo using a RISC-V emulator rather than RISC-5
- For some reason, the compiler incorrectly reads symbol tables within Project Oberon. It reads parameter lengths of 0FFFFFFFFH as 07FH; probably due to reading only a byte instead of the full word. Currently, there is a workaround in the parser that allows parameter lengths of 07FH to be treated the same as 0FFFFFFFFH.
Several open-source projects were used to create this port.
- Of course, Project Oberon itself.
- sam-falvo's Oberon-RV compiler, of which this repository is a fork. It could compile many programs, but had bugs that prevented it from being able to compile the full Oberon system. I've patched most of these, such that it is now self-compiling. Some modules, such as RVAssem, RVDis, and RVOTool, remain either entirely or mostly unchanged.
- pdewacht's Project Norebo, used to create the RISC-V image, of which this repository is also a fork.
- pdewacht's Oberon emulator, used to emulate the created images. My port of the emulator to RISC-V can be found here.
- andreaspirklbauer's Oberon-building-tools, which is included as a submodule of this repository. The documentation on Oberon's boot process is very useful, as is the tooling.