sp1_primitives/utils.rs
1/// Reverse the bits of an integer within a specified bit length.
2///
3/// Takes an integer `x` and reverses its bits within the least significant `bit_len` bits.
4/// For example, reverse_bits_len(0b101, 3) = 0b101 (reversed) = 0b101.
5/// reverse_bits_len(0b001, 3) = 0b100.
6pub fn reverse_bits_len(x: usize, bit_len: usize) -> usize {
7 let mut result = 0;
8 let mut x = x;
9 for _ in 0..bit_len {
10 result = (result << 1) | (x & 1);
11 x >>= 1;
12 }
13 result
14}