SQLite VM

A simple 8-bit stack VM implementation in SQLite.

All SQL is hand written in emulator.sql.
Programs are stored as SQLite database files and can be created with assembler.py.
Samples programs can be found in examples/.

Usage

Assemble a program:

python3 assembler.py examples/sum.asm examples/sum.db

And run it:

./emulator.sh examples/sub.db

Architecture

• 8-bit
• stack based (no registers)
• unlimited stack
• 256 bytes program memory
• 256 bytes RAM

Instruction Set

0 - NOP

1 - PUSH[x]

stack: -> x

2 - POP

stack: _ ->

4 - DUP

stack: x -> x x

5 - PICK[n]

stack: x0 x1 ... xn -> x1 ... xn x0

6 - ADD

stack: x y -> x+y

8 - SUB

stack: x y -> x-y

10 - AND

stack: x y -> x&y

12 - OR

stack: x y -> x|y

14 - NOT

stack: x -> ~x

15 - JUMP[x]

pc: x

16 - JUMPP/RET

stack: x ->
pc: x

17 - JUMPZ[x]

stack: c ->
pc: if c=0, x

18 - JUMPPZ

stack: c x ->
pc: if c=0, x

19 - CALL[x]

stack: -> pc + 2 pc: x

20 - CALLP

stack: x -> pc + 1 pc: x

22 - READ

stack: i -> memory[i]

24 - WRITE

stack: x i -> memory: [i] = x

254 - FIN