https://github.com/akkartik/mu/blob/main/linux/307size.subx
 1 # Size of an array in bytes.
 2 
 3 == code
 4 
 5 size:  # in: (addr array _) -> result/eax: int
 6     # . prologue
 7     55/push-ebp
 8     89/<- %ebp 4/r32/esp
 9     # eax = in
10     8b/-> *(ebp+8) 0/r32/eax
11     #
12     8b/-> *eax 0/r32/eax
13 $size:end:
14     # . epilogue
15     89/<- %esp 5/r32/ebp
16     5d/pop-to-ebp
17     c3/return