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基于Rust的Base58实现

关于Base58的定义、作用，见 1 2.

看一段之前用 Rust 实现的代码。

impl <'a> Encode for BaseX <'a>{
    type Output = String;
    fn encode(&self, source: &[u8]) -> String {

        let base = self.alphabet.len() as u16;

        let mut digits: Vec<u16> = vec![0u16; 1];

        let mut i = 0;
        while i < source.len() {

            let mut j = 0;
            let mut carry: u16 = source[i] as u16;

            let digits_len = digits.len();
            while j < digits_len {
                carry += digits.as_slice()[j] << 8;

                digits.as_mut_slice()[j] = carry % (base as u16);

                carry = (carry / (base as u16)) | 0;

                j += 1;
            }

            while carry > 0 {
                digits.push(carry % (base as u16));
                carry = (carry / base) | 0;
            }

            i += 1;
        }

        let mut string = "".to_string();

        // deal with leading zeros
        let mut k = 0;
        while source[k] == 0 && k < source.len() - 1 {

            string.push(self.alphabet[0] as char);

            k += 1;
        }

        // convert digits to a string
        let mut q: i32 = (digits.len() - 1) as i32;
        while q >= 0 {

            let uu: u8 = self.alphabet[digits[q as usize] as usize];
            let xx = uu as char;

            string.push( xx );

            q -= 1;
        }

        string
    }
}

encode 算法就走三步实现了。

步骤

第一步 辗转除58，求余数

第二步 处理0的情况

第三步 查表

decode 就是个反过程，很简单的小算法。

在进行地址编码的时候， 各家使用的table情况也不一样， 看一下常见的几个。

pub const BITCOIN:  &[u8; 58] = b"123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
pub const RIPPLE:   &[u8; 58] = b"rpshnaf39wBUDNEGHJKLM4PQRST7VWXYZ2bcdeCg65jkm8oFqi1tuvAxyz";
pub const FLICKR:   &[u8; 58] = b"123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ";
pub const SKYWELL:  &[u8; 58] = b"jpshnaf39wBUDNEGHJKLM4PQRST7VWXYZ2bcdeCg65rkm8oFqi1tuvAxyz";

格外说两句

小算法的应用，有成就感。 3

  1. Base58 is Base64 without the number 0 (zero), O (capital letter O), l (small L), I (large i), and the characters “+” and “/”. Or, simply put, it is a set of uppercase and lowercase letters and numbers without the four (0, O, L, I) mentioned above. ↩

  2. Base58 . ↩

  3. base58的Rust实现 . ↩