Enchanted Stone is a logisim-evolution CPU that runs brainfuck instructions. An accurate (and better performing) software simulator is also present.
This is a beginner project and I have no experience in CPU design. What I did may as well be magic, hence the project name. Nevertheless, it was a fun side project!
The first step is to build the toolchain. It supports software CPU simulation and conversion from brainfuck code to binary logisim-evolution ROMs.
$ make
Before using the CPU, brainfuck code needs to be converted to a logisim-evolution ROM. To do it, run:
$ ./toolchain bin [input file]
This outputs the ROM to stdout. Redirect it to the target output file. For example:
$ ./toolchain bin helloworld.bf > helloworld.bin
To load it into logisim-evolution, right-click on the ROM component on the main circuit and
choose "Load Image...". Select the binary file the toolchain created.
The program's input can be set (with the hand tool) in the keyboard field below the terminal output:
Start the simulation by going to Simulate -> Auto-Tick Enabled or pressing Ctrl+K. The CPU's
frequency can also be adjusted on the Simulate menu.
The toolchain includes a simulator. It is written in C for better performance, but it doesn't do any fancy optimizations, as it was designed to behave like the CPU. To run a file:
$ ./toolchain sim [input file]
The simulator tries to emulate the CPU. Though, there are some differences to be noted:
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When the end of the program is reached, the simulator simply stops running. Meanwhile, the CPU needs to modify the cell it is working on, in order to stop program execution. The memory dumps at the end may be, therefore, different.
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The simulator segfaults when reading / writing outside of the memory array. On the other hand, the CPU will likely read / write from the wrong address.
- Documentation
[-]optimization (set cell to zero)- Error detection