enable passing hash function to HMAC PRNG

src/commonMain/kotlin/com/infendro/random/PRNG.kt

@@ -1,5 +1,32 @@
 package com.infendro.random
 
-object PRNG {
-    val HMAC = HMAC()
+import com.infendro.bytearray.toInt
+import com.infendro.hash.HashFunction
+import kotlin.random.Random
+
+abstract class PRNG : Random() {
+    abstract fun reseed(
+        entropy: ByteArray,
+    )
+
+    abstract fun generate(
+        count: Int,
+    ): ByteArray
+
+    override fun nextBits(
+        count: Int,
+    ): Int {
+        if (count !in 0..32) throw Exception()
+        if (count == 0) return 0
+
+        return generate(4).toInt() ushr (32 - count)
+    }
+
+    companion object {
+        fun HMAC(
+            function: HashFunction,
+        ): HMAC {
+            return com.infendro.random.HMAC(function)
+        }
+    }
 }