bitintr 0.1.0

Portable Bit Manipulation Intrinsics.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

use int::Int;

/// Bit Field Extract.
///
/// Extracts bits in range [`start`, `start` + `length`) from the `source` to
/// the least significant bits of the result.
///
/// Bits [7,0] of `range` specify the index to the first bit in the range to be
/// extracted, and bits [15,8] specify the length of the range.
///
/// Only bits up to `std::mem::size_of::<T>() - 1` are extracted.
///
/// The extracted bits are written in the result starting from the
/// least-significant bit. The high-order bits of the result are zeroed.
///
/// # Intrinsic (when available BMI1)
///
/// - [`BEXTR`](http://www.felixcloutier.com/x86/BEXTR.html):
///   Bit field extract (supports 32/64 bit registers).
///
/// # Example
///
/// ```
/// use bitintr::bmi::bextr;
///
/// assert_eq!(bextr(0b0101_0000u8, 4, 4), 0b0000_0101u8);
/// ```
pub fn bextr<T: Int>(source: T, start: T, length: T) -> T {
    (source >> start) & ((T::one() << length) - T::one())
}

pub trait BEXTR {
    fn bextr(self, Self, Self) -> Self;
}

impl<T: Int> BEXTR for T {
    fn bextr(self, start: Self, length: Self) -> Self {
        bextr(self, start, length)
    }
}