# Emulator (ivss)

An **emulator** executes the hypothetical machine's instructions using a program running on the host. ivss reads a linked hex-serialized object and interprets its code:

```bash
$ ./emulator program.hex
```

The emulator initializes `%pc` to `0x40000000` and `%sp` to `0x80000000`, loads sections, and applies relocations. It then repeatedly fetches four instruction bytes, decodes their fields, and updates the simulated registers or memory.

A `halt` instruction ends execution and produces a register-state report. A simple addition program can therefore be checked by examining `%r1` in that report rather than expecting a native executable to run on the host CPU.

Optional behavior is explicit:

```bash
$ ./emulator -debug -timer -terminal program.hex
```

`-debug` prints instruction and register information. `-timer` and `-terminal` start host threads that supply device events; they are not needed for ordinary arithmetic programs. The program must install a handler to receive interrupts. [[ivss-memory-mapped-io|Memory-mapped I/O]] connects its loads and stores to device behavior.

Source: [emulator.c](https://github.com/yanevskiv/ivss/blob/main/src/emulator.c).