implement xoshiro256++ and xoshiro256**

src/commonMain/kotlin/com/infendro/random/prng/Xoshiro256pp.kt

@@ -0,0 +1,28 @@
+package com.infendro.random.prng
+
+import com.infendro.bytes.bytearray.toLongArray
+import com.infendro.hash.sha2.`SHA-256`
+import com.infendro.random.PRNG
+import kotlin.properties.Delegates.notNull
+
+class Xoshiro256pp : PRNG() {
+    private var s: LongArray by notNull()
+
+    override fun seed(seed: ByteArray) {
+        s = `SHA-256`.hash(seed).toLongArray()
+    }
+
+    override fun generate(): Int {
+        val result = (s[0] + s[3]).rotateLeft(23) + s[0]
+
+        val t = s[1] shl 17
+        s[2] = s[2] xor s[0]
+        s[3] = s[3] xor s[1]
+        s[1] = s[1] xor s[2]
+        s[0] = s[0] xor s[3]
+        s[2] = s[2] xor t
+        s[3] = s[3].rotateLeft(45)
+
+        return (result ushr 32).toInt()
+    }
+}

src/commonMain/kotlin/com/infendro/random/prng/Xoshiro256ss.kt

@@ -0,0 +1,28 @@
+package com.infendro.random.prng
+
+import com.infendro.bytes.bytearray.toLongArray
+import com.infendro.hash.sha2.`SHA-256`
+import com.infendro.random.PRNG
+import kotlin.properties.Delegates.notNull
+
+class Xoshiro256ss : PRNG() {
+    private var s: LongArray by notNull()
+
+    override fun seed(seed: ByteArray) {
+        s = `SHA-256`.hash(seed).toLongArray()
+    }
+
+    override fun generate(): Int {
+        val result = (s[1] * 5).rotateLeft(7) * 9
+
+        val t = s[1] shl 17
+        s[2] = s[2] xor s[0]
+        s[3] = s[3] xor s[1]
+        s[1] = s[1] xor s[2]
+        s[0] = s[0] xor s[3]
+        s[2] = s[2] xor t
+        s[3] = s[3].rotateLeft(45)
+
+        return (result ushr 32).toInt()
+    }
+}