dexorder

lib_openzeppelin_contracts/test/helpers/math.js

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+// Array of number or bigint
+const max = (...values) => values.slice(1).reduce((x, y) => (x > y ? x : y), values.at(0));
+const min = (...values) => values.slice(1).reduce((x, y) => (x < y ? x : y), values.at(0));
+const sum = (...values) => values.slice(1).reduce((x, y) => x + y, values.at(0));
+
+// Computes modexp without BigInt overflow for large numbers
+function modExp(b, e, m) {
+  let result = 1n;
+
+  // If e is a power of two, modexp can be calculated as:
+  // for (let result = b, i = 0; i < log2(e); i++) result = modexp(result, 2, m)
+  //
+  // Given any natural number can be written in terms of powers of 2 (i.e. binary)
+  // then modexp can be calculated for any e, by multiplying b**i for all i where
+  // binary(e)[i] is 1 (i.e. a power of two).
+  for (let base = b % m; e > 0n; base = base ** 2n % m) {
+    // Least significant bit is 1
+    if (e % 2n == 1n) {
+      result = (result * base) % m;
+    }
+
+    e /= 2n; // Binary pop
+  }
+
+  return result;
+}
+
+module.exports = {
+  min,
+  max,
+  sum,
+  modExp,
+};