Function zerotrie::byte_phf::f1

pub fn f1(byte: u8, p: u8, n: usize) -> usize

Calculates the function f1 for the PHF. For the exact formula, please read the code.

When p == 0, the operation is a simple modulus.

The argument n is used only for taking the modulus so that the return value is in the range [0, n).

Invariant: n > 0

Examples

use zerotrie::_internal::f1;
const N: usize = 10;

// With p = 0:
assert_eq!(0, f1(0, 0, N));
assert_eq!(1, f1(1, 0, N));
assert_eq!(2, f1(2, 0, N));
assert_eq!(9, f1(9, 0, N));
assert_eq!(0, f1(10, 0, N));
assert_eq!(1, f1(11, 0, N));
assert_eq!(2, f1(12, 0, N));
assert_eq!(9, f1(19, 0, N));

// With p = 1:
assert_eq!(1, f1(0, 1, N));
assert_eq!(0, f1(1, 1, N));
assert_eq!(2, f1(2, 1, N));
assert_eq!(2, f1(9, 1, N));
assert_eq!(4, f1(10, 1, N));
assert_eq!(5, f1(11, 1, N));
assert_eq!(1, f1(12, 1, N));
assert_eq!(7, f1(19, 1, N));