Make NativeRandom internal, use inherited implementations

runtime/src/main/kotlin/kotlin/random/Random.kt

@@ -7,7 +7,7 @@ package kotlin.random
 import kotlin.native.concurrent.AtomicLong
 import kotlin.system.getTimeNanos
 
-public abstract class NativeRandom {
+internal class NativeRandom {
     /**
      * A default pseudo-random linear congruential generator.
      */
@@ -28,39 +28,12 @@ public abstract class NativeRandom {
             _seed.value = seed
         }
 
-        /**
-         * Returns a pseudo-random Int number.
-         */
-        override fun nextInt(): Int {
-            update((seed * MULTIPLIER + 0xbL) and ((1L shl 48) - 1));
-            return (seed ushr 16).toInt();
+        override fun nextBits(bitCount: Int): Int {
+            update((seed * MULTIPLIER + 0xbL) and ((1L shl 48) - 1))
+            return (seed ushr (48 - bitCount)).toInt()
         }
 
-        /**
-         * Returns a pseudo-random Int value between 0 and specified value (exclusive)
-         */
-        override fun nextInt(bound: Int): Int {
-            if (bound <= 0) throw IllegalArgumentException("Incorrect bound: $bound")
-
-            if (bound and (bound - 1) == 0) {
-                return ((bound * (nextInt() ushr 1).toLong()) ushr 31).toInt();
-            }
-
-            var m: Int
-            do {
-                var r = nextInt() ushr 1
-                m = r % bound
-            } while (r - m + (bound - 1) < 0)
-            return m
-        }
-
-        /**
-         * Returns a pseudo-random Long number.
-         */
-        override fun nextLong(): Long = (nextInt().toLong() shl 32) + nextInt().toLong()
-
-        override fun nextBits(bitCount: Int): Int =
-                nextInt().takeUpperBits(bitCount)
+        override fun nextInt(): Int = nextBits(32)
     }
 }