nem catapult バイトレベルで理解する その２ TransferTransaction ref: https://qiita.com/planethouki/items/025d44f2ebe6cfcb4b1f

file1.txt

new Mosaic(new MosaicId('nem:xem'), UInt64.fromUint(10000000))

file3.txt

$ node
> number = 0x0001F8645223984F
1378064463
> number & 0xFFFFFFFF
1378064463
> (number & 0xFFFFFFFF) >>> 0
1378064463
> (1378064463).toString(16).toUpperCase()
'5223984F'

file4.txt

$ node
> number = 0x0001F8645223984F
1378064463
> number / 0x100000000
129124.32085563592
> (number / 0x100000000) >>> 0
129124
> (129124).toString(16).toUpperCase()
'1F864'

file5.txt

> nem2Sdk.UInt64.fromUint(2729735958921713743);
UInt64 { lower: 1378064384, higher: 635566180 }

file6.txt

{ lower: 0x52239800, higher: 0x25E1F864 }

TransferTransactionSchema.js

/**
 * Transfer transaction schema
 * @const {module:schema/Schema}
 */
const schema = new Schema([
    uint('size'),
    array('signature'),
    array('signer'),
    ushort('version'),
    ushort('type'),
    array('fee', TypeSize.INT),
    array('deadline', TypeSize.INT),
    array('recipient'),
    ushort('messageSize'),
    ubyte('numMosaics'),
    table('message', [
        ubyte('type'),
        array('payload')
    ]),
    tableArray('mosaics', [
        array('id', TypeSize.INT),
        array('amount', TypeSize.INT)
    ])
]);

uint64.js

/**
 * Converts a numeric unsigned integer into a uint64.
 * @param {number} number The unsigned integer.
 * @returns {module:coders/uint64~uint64} The uint64 representation of the input.
 */
fromUint: number => {
    const value = [(number & 0xFFFFFFFF) >>> 0, (number / 0x100000000) >>> 0];
    //if (0x00200000 <= value[1] || 0 > number || 0 !== (number % 1))
    //  throw Error(`number cannot be converted to uint '${number}'`);

    return value;
},