Add forgotten file

benchmark/common_fast.pyx

@@ -0,0 +1,20 @@
+from libc.stdint cimport *
+
+cdef uint32_t A = 1664525
+cdef uint32_t C = 1013904223
+cdef uint32_t state = C
+cdef int32_t MAX_INT = 2**31 - 1
+
+cpdef uint32_t nextFastRand():
+  global state
+  state = A * state + C
+  return state
+
+cpdef uint32_t rand_int(uint32_t range):
+  return nextFastRand() % range
+
+cpdef double rand_double(double range):
+  return nextFastRand() * range / MAX_INT
+
+cpdef bint rand_bool():
+  return nextFastRand() % 2