Enum data_encoding::BitOrder
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pub enum BitOrder { MostSignificantFirst, LeastSignificantFirst, }
Order in which bits are read from a byte
The base-conversion encoding is always little-endian. This means that the least significant byte is always first. However, we can still choose whether, within a byte, this is the most significant or the least significant bit that is first. If the terminology is confusing, testing on an asymmetrical example should be enough to choose the correct value.
Examples
In the following example, we can see that a base with the
MostSignificantFirst
bit-order has the most significant bit first in the
encoded output. In particular, the output is in the same order as the bits
in the byte. The opposite happens with the LeastSignificantFirst
bit-order. The least significant bit is first and the output is in the
reverse order.
use data_encoding::{Specification, BitOrder}; let mut spec = Specification::new(); spec.symbols.push_str("01"); // spec.bit_order = BitOrder::MostSignificantFirst; // default let msb = spec.encoding().unwrap(); spec.bit_order = BitOrder::LeastSignificantFirst; let lsb = spec.encoding().unwrap(); assert_eq!(msb.encode(&[0b01010011]), "01010011"); assert_eq!(lsb.encode(&[0b01010011]), "11001010");
Variants
MostSignificantFirst
Most significant bit first
This is the most common and most intuitive bit-order. In particular, this is the bit-order used by RFC4648 and thus the usual hexadecimal, base64, base32, base64url, and base32hex encodings. This is the default bit-order when specifying a base.
LeastSignificantFirst
Least significant bit first
Examples
Here is how one would implement the DNSCurve base32 encoding:
let dns_curve = { use data_encoding::{Specification, BitOrder}; let mut spec = Specification::new(); spec.symbols.push_str("0123456789bcdfghjklmnpqrstuvwxyz"); spec.translate.from.push_str("BCDFGHJKLMNPQRSTUVWXYZ"); spec.translate.to.push_str("bcdfghjklmnpqrstuvwxyz"); spec.bit_order = BitOrder::LeastSignificantFirst; spec.encoding().unwrap() }; assert_eq!(dns_curve.encode(&[0x64, 0x88]), "4321"); assert_eq!(dns_curve.decode(b"4321").unwrap(), vec![0x64, 0x88]);
Trait Implementations
impl Debug for BitOrder
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impl Copy for BitOrder
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impl Clone for BitOrder
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fn clone(&self) -> BitOrder
Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)
1.0.0
Performs copy-assignment from source
. Read more
impl PartialEq for BitOrder
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fn eq(&self, __arg_0: &BitOrder) -> bool
This method tests for self
and other
values to be equal, and is used by ==
. Read more
fn ne(&self, other: &Rhs) -> bool
1.0.0
This method tests for !=
.