Internal Structure

Loading assembly files:

In order to load an assembly file, you need to instantiate a CPU with the capabilities you want. Loading an assembly file is the done in multiple steps:

• An RiscVInput is created, this represents the file internally

• An RiscVTokenizer is created by calling cpu.get_tokenizer().

• The input is tokenized by calling .tokenize() on the tokenizer.

• The tokens can then be converted to an Executable, this will then hold all the information such as name, sections, symbols, etc. This is done by creating an ExecutableParser(tk: RiscVTokenizer) and the calling parse().

• Now you have a representation of the assembly file that can be loaded into memory by calling cpu.load(executable), this will internally construct a LoadedExecutable, which represents the actual memory regions the executable contains (and some meta information such as symbols).

• You can load as many executables as you want into memory. If you want to run one, you pass it to run_loaded(loaded_bin) method of the cpu.

You shouldn’t have to do this manually, as the riscemu/__main__.py has all the necessary code.

Instruction sets

Each instruction set is in a separate file in riscemu/instructions/. All instruction sets have to inherit from the InstructionSet class that sets up all the relevant helpers and loading code.

Creating a cpu with certain instruction sets is done by passing the CPU constructor a list of instruction set classes:

cpu = CPU(config, [RV32I, RV32M])