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committed d0894409d17/* * This implements the binary GCD algorithm. (Often attributed to Stein, * but as Knuth has noted, appears in a first-century Chinese math text.) * * This is faster than the division-based algorithm even on x86, which * has decent hardware division. *//* If __ffs is available, the even/odd algorithm benchmarks slower. *//** * gcd - calculate and return the greatest common divisor of 2 unsigned longs * @a: first value * @b: second value */unsigned long gcd(unsigned long a, unsigned long b){ unsigned long r = a | b; if (!a || !b) return r; b >>= __ffs(b); if (b == 1) return r & -r; for (;;) { a >>= __ffs(a); if (a == 1) return r & -r; if (a == b) return a << __ffs(r); if (a < b) swap(a, b); a -= b; }}/* If normalization is done by loops, the even/odd algorithm is a win. */unsigned long gcd(unsigned long a, unsigned long b){ unsigned long r = a | b; if (!a || !b) return r; /* Isolate lsbit of r */ r &= -r; while (!(b & r)) b >>= 1; if (b == r) return r;