Stake shares on curve

contracts/staking/stakeManager/StakeManagerExtension.sol

@@ -179,4 +179,8 @@ contract StakeManagerExtension is StakeManagerStorage, Initializable, StakeManag
         }
         return _eventsHub;
     }
+
+    function setSharesK(uint256 k) external onlyGovernance {
+        sharesK = k.mul(SHARES_PRECISION);
+    }
 }

contracts/staking/stakeManager/StakeManagerStorage.sol

@@ -23,11 +23,13 @@ contract StakeManagerStorage is GovernanceLockable, RootChainable {
     struct State {
         uint256 amount;
         uint256 stakerCount;
+        uint256 shares;
     }
 
     struct StateChange {
         int256 amount;
         int256 stakerCount;
+        int256 shares;
     }
 
     struct Validator {
@@ -49,6 +51,7 @@ contract StakeManagerStorage is GovernanceLockable, RootChainable {
     uint256 constant MAX_COMMISION_RATE = 100;
     uint256 constant MAX_PROPOSER_BONUS = 100;
     uint256 constant REWARD_PRECISION = 10**25;
+    uint256 public constant SHARES_PRECISION = 10**12;
     uint256 internal constant INCORRECT_VALIDATOR_ID = 2**256 - 1;
     uint256 internal constant INITIALIZED_AMOUNT = 1;
 

contracts/staking/stakeManager/StakeManagerStorageExtension.sol

@@ -1,6 +1,12 @@
 pragma solidity 0.5.17;
 
 contract StakeManagerStorageExtension {
+    struct StakeSharesState {
+        uint256 sharesPool;
+        uint256 stakePool;
+        uint256 shares;
+    }
+
     address public eventsHub;
     uint256 public rewardPerStake;
     address public extensionCode;
@@ -14,4 +20,8 @@ contract StakeManagerStorageExtension {
     uint256 public maxRewardedCheckpoints;
     // increase / decrease value for faster or slower checkpoints, 0 - 100%
     uint256 public checkpointRewardDelta;
+    // constant for stake shares curve
+    uint256 public sharesK;
+    // validator Id => state
+    mapping(uint256 => StakeSharesState) public sharesState;
 }