The most trivial virtual machine for education purposes. It can run a few x86 machine code instructions on Windows OS. I never tried to build it on Linux but it should be possible.
The VM is very slow because it copies the instruction being executed to an executable buffer and runs it directly.
This project was introduced at hysteria session 2011.
The LDE64.lib is Lenght Disassembler. It comes from https://github.com/BeaEngine/lde64.
- Visual compiler and linker
- NASM
Another toolchain can be used too but beware of command line options. For more see the batch files.
The build batch files produce listings in assembler language. The listing shows what instructions actually run in the VM.
The core functionality is located in execute.asm. The instruction being executed is stored in execute_instruction_buffer first, execute_instruction() is called to execute it then.
The vm1.c is the simplest VM possible. It consists of few tens of lines of simple C and asm code.
It merely runs very simple code:
printf("%s World\n\n\n", "Hysteria");
exit(0);
The vm2.c builds on VM1 and shows how to resolve branch instructions that can't be executed directly. It runs slightly more complicated code:
int number;
printf("enter decimal number: ");
if (1 != scanf("%d", &number)) {
printf("error, exiting...\n");
exit(1);
}
printf ("hexadecimal: %X\n", number);
exit(0);