From d7025e261a98aeedfed53d7014bab6acbeb7deb6 Mon Sep 17 00:00:00 2001
From: Piotr Dyraga <piotr.dyraga@keep.network>
Date: Fri, 21 Aug 2020 15:11:23 +0200
Subject: [PATCH 1/2] Refactored the loop in RNG.bitsRequired

The loop should work exactly the same as before except that we avoid the
comparison of bits >= 0 which is always true because bits is an uint.
---
 contracts/RNG.sol | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/contracts/RNG.sol b/contracts/RNG.sol
index 611216d0..7ccd724f 100644
--- a/contracts/RNG.sol
+++ b/contracts/RNG.sol
@@ -135,22 +135,22 @@ library RNG {
   /// @return uint The smallest number of bits
   /// that can contain the number `range-1`.
   function bitsRequired(uint256 range) internal pure returns (uint256) {
-    uint256 bits;
     // Start at 19 to be faster for large ranges
-    for (bits = (POSITION_BITS - 1); bits >= 0; bits--) {
-      // Left shift by `bits`,
-      // so we have a 1 in the (bits + 1)th least significant bit
-      // and 0 in other bits.
-      // If this number is equal or greater than `range`,
-      // the range [0, range-1] fits in `bits` bits.
-      //
-      // Because we loop from high bits to low bits,
-      // we find the highest number of bits that doesn't fit the range,
-      // and return that number + 1.
-      if (1 << bits < range) {
-        break;
-      }
+    uint256 bits = POSITION_BITS - 1;
+
+    // Left shift by `bits`,
+    // so we have a 1 in the (bits + 1)th least significant bit
+    // and 0 in other bits.
+    // If this number is equal or greater than `range`,
+    // the range [0, range-1] fits in `bits` bits.
+    //
+    // Because we loop from high bits to low bits,
+    // we find the highest number of bits that doesn't fit the range,
+    // and return that number + 1.
+    while (1 << bits >= range) {
+      bits--;
     }
+
     return bits + 1;
   }
 

From 5588f317e55a113b75ede5b8feab70d00be0af0e Mon Sep 17 00:00:00 2001
From: Piotr Dyraga <piotr.dyraga@keep.network>
Date: Fri, 21 Aug 2020 15:13:20 +0200
Subject: [PATCH 2/2] Initialize the index in RNG.getIndex function

Initializing the index does not change how the function works and, in
fact, index when not initialized is initialized to the default - 0
value. We can however make this code a little cleaner and Slither
happier.
---
 contracts/RNG.sol | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contracts/RNG.sol b/contracts/RNG.sol
index 7ccd724f..e4272cd7 100644
--- a/contracts/RNG.sol
+++ b/contracts/RNG.sol
@@ -197,7 +197,7 @@ library RNG {
   {
     uint256 bits = bitsRequired(range);
     bool found = false;
-    uint256 index;
+    uint256 index = 0;
     bytes32 newState = state;
     while (!found) {
       index = truncate(bits, uint256(newState));