fibonacci.txt

uint16_t fibonacci(uint16_t n)
{
  uint16_t first = 1;
  uint16_t second = 1;
  
  while(n > 1) {
    uint16_t tmp = first + second;
    second = first;
    first = tmp;

    --n;
  }

  return first;
}

// r0: program counter
// r1: stack pointer
// r2-r5: function args
// r6: function return values
// mov ra, rb = lfun 0b1010, ra, rb
// and ra, c = lfun 0b1000, ra, c

fibonacci:
  mov r3, 1
  mov r4, 1
  mov r0, fibonacci_loc0

fibonacci_loc1:
  mov r5, r3
  add r5, r4
  mov r4, r3
  mov r3, r5

  add r2, -1

fibonacci_loc0:
  mov r5, r2
  and r5, 0xfffe
  bnez r5, fibonacci_loc1

  mov r6, r3
  pop r0