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19 lines
476 B
19 lines
476 B
4 years ago
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'use strict';
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const { promisify } = require('util')
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, randomBytes = promisify(require('crypto').randomBytes);
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module.exports = async (min, max) => {
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if (max <= min) return min;
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const mod = max - min + 1;
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const div = Math.ceil(Math.log2(mod));
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const numberBytes = Math.ceil(div / 4);
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const mask = (1 << div) - 1;
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let rand;
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do {
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rand = (await randomBytes(numberBytes)).readUIntBE(0, numberBytes);
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rand = rand & mask;
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} while (rand >= mod);
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return rand + min;
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}
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