regs:
instr ptr (ip)
stack ptr (sp)
alternative input (ai)

instructions:
arith:

               | immediate operand
               || clear input
               ||| flip input
               |||| offset (from sp)
00xxx fCFddddd iCFss2ss iCFss1ss
  op  ||| flip ai (before performing the arith computation)
      || clear ai (same as above)
      | flip output (that gets written to the dest)

b = ai & 1

dst,ai = 0x1234DEAD is the same as dst = 0x1234, ai = 0xDEAD

000: dst,ai = s1 + s2 + b
001: dst,ai = s1 * s2 + r
010: dst,ai = s1 << s2 | ai
011: dst,ai = s1 >> s2 | ai
100: dst    = s1 & s2
101: dst    = s1 ^ s2
110: dst,ai = s1 / s2
111: dst,ai = r,s1

mem:
01wxx fCFddddd iCFss2ss iCFss1ss
  | read/write

0xx: d = mem[s1 + ai << x], ai++
1xx: mem[s1 + ai << x] = s2, ai++

flow:
10sxx fCFddddd iCFss2ss iCFss1ss
  | set dest register to the computed address

addr = s1 + s2 << x
if(s) dst = addr;
if(b) ip = addr

stack:
//im not too sure what kinds of instructions i should have here
11000 -------- -------- aaaaaaaa | sp += a;
1111- iiiiiiii iiiiiiii aaaaaaaa | sp += a; mem[sp] = ip; ip = i //behaves similarly to a call instr
11001 -------- -------- aaaaaaaa | sp += a; ip = mem[sp]; //behaves similarly to a ret instr when a = 0