add twap switch

contracts/DODOVendingMachine/impl/DVMStorage.sol

@@ -14,10 +14,13 @@ import {DODOMath} from "../../lib/DODOMath.sol";
 import {DecimalMath} from "../../lib/DecimalMath.sol";
 import {IFeeRateModel} from "../../lib/FeeRateModel.sol";
 import {IERC20} from "../../intf/IERC20.sol";
+import {PMMPricing} from "../../lib/PMMPricing.sol";
 
 contract DVMStorage is ReentrancyGuard {
     using SafeMath for uint256;
 
+    bool public _IS_OPEN_TWAP_ = false;
+
     // ============ Core Address ============
 
     address public _MAINTAINER_;
@@ -25,8 +28,11 @@ contract DVMStorage is ReentrancyGuard {
     IERC20 public _BASE_TOKEN_;
     IERC20 public _QUOTE_TOKEN_;
 
-    uint128 public _BASE_RESERVE_;
-    uint128 public _QUOTE_RESERVE_;
+    uint112 public _BASE_RESERVE_;
+    uint112 public _QUOTE_RESERVE_;
+    uint32 public _BLOCK_TIMESTAMP_LAST_;
+
+    uint256 public _BASE_PRICE_CUMULATIVE_LAST_;
 
     // ============ Shares (ERC20) ============
 
@@ -51,4 +57,45 @@ contract DVMStorage is ReentrancyGuard {
     IFeeRateModel public _MT_FEE_RATE_MODEL_;
     uint256 public _K_;
     uint256 public _I_;
+
+
+    // ============ Helper Functions ============
+
+    function getPMMState() public view returns (PMMPricing.PMMState memory state) {
+        state.i = _I_;
+        state.K = _K_;
+        state.B = _BASE_RESERVE_;
+        state.Q = _QUOTE_RESERVE_;
+        state.B0 = 0; // will be calculated in adjustedTarget
+        state.Q0 = 0;
+        state.R = PMMPricing.RState.ABOVE_ONE;
+        PMMPricing.adjustedTarget(state);
+    }
+
+    function getPMMStateForCall() 
+        external 
+        view 
+        returns (
+            uint256 i,
+            uint256 K,
+            uint256 B,
+            uint256 Q,
+            uint256 B0,
+            uint256 Q0,
+            uint256 R
+        )
+    {
+        PMMPricing.PMMState memory state = getPMMState();
+        i = state.i;
+        K = state.K;
+        B = state.B;
+        Q = state.Q;
+        B0 = state.B0;
+        Q0 = state.Q0;
+        R = uint256(state.R);
+    }
+
+    function getMidPrice() public view returns (uint256 midPrice) {
+        return PMMPricing.getMidPrice(getPMMState());
+    }
 }