corewar

Written with Jéremy Gagnot and Thibaut Fontaine

Corewar is a pretty confusing project involving a questionable VM and some pieces of bytecode fighting for their life.

It is divided in two parts.

The VM

Rules

• The VM allocates some memory in which the processes will fight. This memory is circular.
• Every cycle, each process is executed. Its PC moves to the next byte and tries to execute an instruction there.
• Each instruction takes a set time to execute. (forking a process takes 1000 cycles for example).
• Each process has access to 16 registers.
• Every set number of cycles, the VM kills every process that hasn't executed the live instruction
• The last process alive is declared winner.

The pseudo-ASM compiler

The code in the asm folder produces a compiler that compiles pseudo assembly code.

There are 16 instructions :

• live : makes the process live
• ld, ldi, lld, lldi : load memory bytes into a process' register.
• st, sti : writes a process' register onto the memory.
• add, sub
• and, or, xor
• fork, lfork : forks the process
• zjmp : jumps the PC if the process' internal "carry" is 0
• aff : display a byte to stdout

Parameters types :

• register : one byte, r1 to r16
• direct : two or four bytes
• indirect : two bytes

Syntax :

.name "[program name]"
.comment "[program description]"

[label_definition]:
  [instruction] [indirect_arg],%[direct_arg],:[label_name]
 
 #comment

Encoding

One instuction =

• One byte for the opcode
• One byte for the parameter types
• N bytes for the parameters themselves

Arguments encoding

0x  xx   xx   xx  00
   arg1 arg2 arg3
   
With  01 : register
      10 : direct
      11 : indirect