如何根据difficulty来计算target

kingccc · October 8, 2019, 9:38am

difficulty为1对应的target是多少，具体算法是怎样的

cool007zqw · October 8, 2019, 11:29am

同问。

这段代码似乎有它们的计算关系，但是我自己手动算了一下结果不对。

nervosnetwork/ckb/blob/d2708b4a8849c509099eb2df69a4f27667bc80be/util/types/src/utilities/difficulty.rs#L10


use numext_fixed_uint::prelude::UintConvert;
use numext_fixed_uint::{u512, U256, U512};


pub const DIFF_TWO: u32 = 0x2080_0000;


const ONE: U256 = U256::one();
// ONE << 256
const HSPACE: U512 = u512!("0x10000000000000000000000000000000000000000000000000000000000000000");


fn target_to_difficulty(target: &U256) -> U256 {
    if target == &ONE {
        U256::max_value()
    } else {
        let (target, _): (U512, bool) = target.convert_into();
        (HSPACE / target).convert_into().0
    }
}


fn difficulty_to_target(difficulty: &U256) -> U256 {
    if difficulty == &ONE {

thewawar · October 9, 2019, 7:09am

是下面的 compact_to_difficulty

BTW, ckb-cli 会提供相应的转换子命令。

kingccc · October 9, 2019, 7:18am

现在的问题是要用c语言实现，原理是不是与btc类似，难度为1的目标值是多少？

kingccc · October 9, 2019, 7:28am

是否可以详细讲一下target的计算方式，类似btc如下

zhangsoledad · November 22, 2019, 9:36am

compact_target 可以到 wiki 里查看

difficulty 和 target 转换如下:
HSPACE = 1 << 256
difficulty = HSPACE / target

tengchitim · November 25, 2019, 10:45am

大佬们有人知道CKB的出块间隔哪里有说明吗？我目前只看到资料都是说是变动的，但一般大概会有个参考值来做平衡的吧？我们想理论点计算一下CKB的出块数，大概评估一下自己这边的挖矿收益。

janx · November 26, 2019, 1:46am

github.com

nervosnetwork/ckb/blob/develop/spec/src/consensus.rs#L52


const TAU: u64 = 2;


// We choose 1_000 because it is largest number between MIN_EPOCH_LENGTH and MAX_EPOCH_LENGTH that
// can divide INITIAL_PRIMARY_EPOCH_REWARD and can be divided by ORPHAN_RATE_TARGET_RECIP.
pub(crate) const GENESIS_EPOCH_LENGTH: u64 = 1_000;


// o_ideal = 1/40 = 2.5%
const ORPHAN_RATE_TARGET: RationalU256 = RationalU256::new_raw(U256::one(), u256!("40"));


const MAX_BLOCK_INTERVAL: u64 = 48; // 48s
const MIN_BLOCK_INTERVAL: u64 = 8; // 8s


// cycles of a typical two-in-two-out tx
pub const TWO_IN_TWO_OUT_CYCLES: Cycle = 3_500_000;
// bytes of a typical two-in-two-out tx
pub const TWO_IN_TWO_OUT_BYTES: u64 = 597;
// count of two-in-two-out txs a block should capable to package
const TWO_IN_TWO_OUT_COUNT: u64 = 1_000;
pub(crate) const DEFAULT_EPOCH_DURATION_TARGET: u64 = 4 * 60 * 60; // 4 hours, unit: second
const MILLISECONDS_IN_A_SECOND: u64 = 1000;
const MAX_EPOCH_LENGTH: u64 = DEFAULT_EPOCH_DURATION_TARGET / MIN_BLOCK_INTERVAL; // 1800

出块时间的调整目标上下限是8s和48s，目标叔块率是2.5%。目前大部分时间是在8s附近浮动。