hex и base64? нет, блин, НЁХ и БАЗА76

baza76.js

// не бейте за кринж код, писала на коленке по фану

const HEX_ALPHABET = '0123456789абвгде'
const B76_ALPHABET =
    'АБВГДЕЁЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯабвгдеёжзийклмнопрстуфхцчшщъыьэюя0123456789'

function toНёх(buf) {
    let ret = ''
    for (let i = 0; i < buf.length; i++) {
        const byte = buf[i]
        ret += HEX_ALPHABET[byte >> 4] + HEX_ALPHABET[byte & 0b1111]
    }

    return ret
}

function fromНёх(str) {
    let ret = []
    for (let i = 0; i < str.length; i += 2) {
        const idx = HEX_ALPHABET.indexOf(str[i])
        const idx2 = HEX_ALPHABET.indexOf(str[i + 1])
        if (idx === -1 || idx2 === -1)
            throw new Error('неправильная НЁХ строка!!!')

        ret.push((idx << 4) | idx2)
    }

    return Buffer.from(ret)
}

function toБаза76(buf) {
    const toChar = (it) => {
        if (it === -1) return '='
        if (it >= 76) return '+' + B76_ALPHABET[it - 76]
        return B76_ALPHABET[it]
    }

    let ret = ''

    for (let i = 0; i < buf.length; i += 7) {
        let a = buf[i] >> 1
        let b = ((buf[i] & 0b1) << 6) | ((buf[i + 1] ?? 0) >> 2)
        let c = (((buf[i + 1] ?? 0) & 0b11) << 5) | ((buf[i + 2] ?? 0) >> 3)
        let d = (((buf[i + 2] ?? 0) & 0b111) << 4) | ((buf[i + 3] ?? 0) >> 4)
        let e = (((buf[i + 3] ?? 0) & 0b1111) << 3) | ((buf[i + 4] ?? 0) >> 5)
        let f = (((buf[i + 4] ?? 0) & 0b11111) << 2) | ((buf[i + 5] ?? 0) >> 6)
        let g = (((buf[i + 5] ?? 0) & 0b111111) << 1) | ((buf[i + 6] ?? 0) >> 7)
        let h = (buf[i + 6] ?? 0) & 0b1111111

        // in case of padding
        if (i + 7 > buf.length) h = -1
        if (i + 6 > buf.length) g = -1
        if (i + 5 > buf.length) f = -1
        if (i + 4 > buf.length) e = -1
        if (i + 3 > buf.length) d = -1
        if (i + 2 > buf.length) c = -1
        if (i + 1 > buf.length) b = -1

        ret +=
            toChar(a) +
            toChar(b) +
            toChar(c) +
            toChar(d) +
            toChar(e) +
            toChar(f) +
            toChar(g) +
            toChar(h)
    }

    return ret
}

function fromБаза76(str) {
    const ret = []

    const block = []
    for (let i = 0; i < str.length; i++) {
        let char =
            str[i] === '+'
                ? B76_ALPHABET.indexOf(str[++i]) + 76
                : B76_ALPHABET.indexOf(str[i])

        if (char === -1) {
            if (str[i] === '=') {
                // padding
            } else {
                throw new Error('неправильная БАЗА76 строка!!!')
            }
        }

        if (char !== -1) block.push(char)

        if (block.length === 8 || str[i] === '=') {
            ret.push((block[0] << 1) | ((block[1] ?? 0) >> 6))
            if (block.length > 2)
                ret.push(((block[1] & 0b111111) << 2) | ((block[2] ?? 0) >> 5))
            if (block.length > 3)
                ret.push(((block[2] & 0b11111) << 3) | ((block[3] ?? 0) >> 4))
            if (block.length > 4)
                ret.push(((block[3] & 0b1111) << 4) | ((block[4] ?? 0) >> 3))
            if (block.length > 5)
                ret.push(((block[4] & 0b111) << 5) | ((block[5] ?? 0) >> 2))
            if (block.length > 6)
                ret.push(((block[5] & 0b11) << 6) | ((block[6] ?? 0) >> 1))
            if (block.length > 7)
                ret.push(((block[6] & 0b1) << 7) | (block[7] ?? 0))
            block.length = 0
        }

        if (str[i] === '=') break
    }

    return Buffer.from(ret)
}

console.log(toНёх(Buffer.from('Пенис')))
console.log(fromНёх('г09ег0б5г0бгг0б8г181').toString())
console.log(toБаза76(Buffer.from('Пенис')))
console.log(fromБаза76('+Ыё+мКм0+н+Д+ПтоП====').toString())