Struct bdk_chain::bitcoin::CompactTarget

pub struct CompactTarget(/* private fields */);
Expand description

Encoding of 256-bit target as 32-bit float.

This is used to encode a target into the block header. Satoshi made this part of consensus code in the original version of Bitcoin, likely copying an idea from OpenSSL.

OpenSSL’s bignum (BN) type has an encoding, which is even called “compact” as in bitcoin, which is exactly this format.

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impl CompactTarget

pub fn from_hex(s: &str) -> Result<CompactTarget, PrefixedHexError>

Creates a CompactTarget from an prefixed hex string.

pub fn from_unprefixed_hex(s: &str) -> Result<CompactTarget, UnprefixedHexError>

Creates a CompactTarget from an unprefixed hex string.

pub fn from_next_work_required( last: CompactTarget, timespan: u64, params: impl AsRef<Params> ) -> CompactTarget

Computes the CompactTarget from a difficulty adjustment.

ref: https://github.com/bitcoin/bitcoin/blob/0503cbea9aab47ec0a87d34611e5453158727169/src/pow.cpp

Given the previous Target, represented as a CompactTarget, the difficulty is adjusted by taking the timespan between them, and multipling the current CompactTarget by a factor of the net timespan and expected timespan. The CompactTarget may not adjust by more than a factor of 4, or adjust beyond the maximum threshold for the network.

§Note

Under the consensus rules, the difference in the number of blocks between the headers does not equate to the difficulty_adjustment_interval of Params. This is due to an off-by-one error, and, the expected number of blocks in between headers is difficulty_adjustment_interval - 1 when calculating the difficulty adjustment.

Take the example of the first difficulty adjustment. Block 2016 introduces a new CompactTarget, which takes the net timespan between Block 2015 and Block 0, and recomputes the difficulty.

§Returns

The expected CompactTarget recalculation.

pub fn from_header_difficulty_adjustment( last_epoch_boundary: Header, current: Header, params: impl AsRef<Params> ) -> CompactTarget

Computes the CompactTarget from a difficulty adjustment, assuming these are the relevant block headers.

Given two headers, representing the start and end of a difficulty adjustment epoch, compute the CompactTarget based on the net time between them and the current CompactTarget.

§Note

See CompactTarget::from_next_work_required

For example, to successfully compute the first difficulty adjustment on the Bitcoin network, one would pass the header for Block 2015 as current and the header for Block 0 as last_epoch_boundary.

§Returns

The expected CompactTarget recalculation.

pub fn from_consensus(bits: u32) -> CompactTarget

Creates a CompactTarget from a consensus encoded u32.

pub fn to_consensus(self) -> u32

Returns the consensus encoded u32 representation of this CompactTarget.

Trait Implementations§

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impl Clone for CompactTarget

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fn clone(&self) -> CompactTarget

Returns a copy of the value. Read more
1.0.0 · source§

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for CompactTarget

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fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter. Read more
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impl Decodable for CompactTarget

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fn consensus_decode<R>(r: &mut R) -> Result<CompactTarget, Error>
where R: Read + ?Sized,

Decode an object with a well-defined format. Read more
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fn consensus_decode_from_finite_reader<R>(reader: &mut R) -> Result<Self, Error>
where R: Read + ?Sized,

Decode Self from a size-limited reader. Read more
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impl Default for CompactTarget

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fn default() -> CompactTarget

Returns the “default value” for a type. Read more
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impl<'de> Deserialize<'de> for CompactTarget

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fn deserialize<__D>( __deserializer: __D ) -> Result<CompactTarget, <__D as Deserializer<'de>>::Error>
where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer. Read more
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impl Encodable for CompactTarget

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fn consensus_encode<W>(&self, w: &mut W) -> Result<usize, Error>
where W: Write + ?Sized,

Encodes an object with a well-defined format. Read more
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impl From<CompactTarget> for Target

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fn from(c: CompactTarget) -> Target

Converts to this type from the input type.
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impl Hash for CompactTarget

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fn hash<__H>(&self, state: &mut __H)
where __H: Hasher,

Feeds this value into the given Hasher. Read more
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fn hash_slice<H>(data: &[Self], state: &mut H)
where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher. Read more
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impl LowerHex for CompactTarget

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fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter. Read more
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impl Ord for CompactTarget

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fn cmp(&self, other: &CompactTarget) -> Ordering

This method returns an Ordering between self and other. Read more
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fn max(self, other: Self) -> Self
where Self: Sized,

Compares and returns the maximum of two values. Read more
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fn min(self, other: Self) -> Self
where Self: Sized,

Compares and returns the minimum of two values. Read more
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fn clamp(self, min: Self, max: Self) -> Self
where Self: Sized + PartialOrd,

Restrict a value to a certain interval. Read more
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impl PartialEq for CompactTarget

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fn eq(&self, other: &CompactTarget) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl PartialOrd for CompactTarget

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fn partial_cmp(&self, other: &CompactTarget) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
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fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
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fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
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fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
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fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl Serialize for CompactTarget

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fn serialize<__S>( &self, __serializer: __S ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>
where __S: Serializer,

Serialize this value into the given Serde serializer. Read more
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impl UpperHex for CompactTarget

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fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter. Read more
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impl Copy for CompactTarget

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impl Eq for CompactTarget

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impl StructuralPartialEq for CompactTarget

Auto Trait Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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Performs the conversion.
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impl<V, T> VZip<V> for T
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fn vzip(self) -> V

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impl<T> DeserializeOwned for T
where T: for<'de> Deserialize<'de>,