#+TITLE Project Specification

* Binary interface

The VM does not use floating point numbers, it instead uses fixed point numbers.

This is for portability reasons as some devices might not have a FPU in them

especially microcontrollers and some retro game systems like the PS1.

** Numbers
| type | size (bytes) | description                           |
|------+--------------+---------------------------------------|
| u8   |            1 | unsigned 8bit, alias =char= and =byte=    |
| bool |            1 | unsigned 8bit, =false= or =true=          |
| i8   |            1 | signed 8bit for interop               |
| u16  |            2 | unsigned 16bit for interop            |
| i16  |            2 | signed 16bit for interop              |
| u32  |            4 | unsigned 32bit, alias =nat=             |
| i32  |            4 | signed 32bit, alias =int=               |
| f32  |            4 | signed 32bit fixed number, alias =real= |

* Memory

Uses a harvard style archecture, meaning the code and ram memory
are split up into two seperate blocks.

In the C version you can see these are two seperate arrays 'code' and 'mem'.

During compilation constants and local variables are put onto 'mem'

* Opcodes

Most opcodes are 4 bytes

[opcode][dest][src1][src2]

A small number are multibyte like load-long-immidiate

[multibyte-opcode][0u8][0u8][opcode] . [u32]

These are decoded during runtime and selected.

In theory, bitshift decoding is faster than
accessing an unknown n bytes of memory in the 'code' array.