> (--(char)hash_ptr.parm.v.p) = fpop(sst);

If I'm understanding correctly, it looks like it's saying "assign the string (i.e. char) returned from `fpop(sst)` into the slot before hash_ptr.parm.v.p`. It definitely seems unnecessarily obtuse; casting a value to a pointer, then decrementing it to get the address of the location before it and then dereferencing that to assign to. I honestly can't recall off the top of my head if doing `--some_pointer_value` would mean `some_pointer_value - 1` or `some_pointer_value - sizeof(char)`, which is always something that used to trip me up.