Simulate the process: while the number is greater than 0, if it is even divide by 2, otherwise subtract 1. Count each operation.

The number of steps equals the number of set bits (subtract-1 operations) plus the number of bits minus 1 (divide-by-2 operations after the first 1). For num > 0, this is `bit_count(num) + bit_length(num) - 1`.

For a power of 2 (num = 2^k, k >= 1), the steps equal k + 1: k divisions by 2 to reach 1, then one subtraction. For num = 1, steps = 1.