Add sha384 and unit tests.

contracts/TestSha2.sol

@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity 0.8.15;
+
+import { Sha2Ext } from "./lib/Sha2Ext.sol";
+import { LibBytes } from "./lib/LibBytes.sol";
+
+contract TestSha2 {
+    // modify the storage of the contract so that the gas cost of the test is measured.
+    bool public success;
+
+    function sha384External(bytes calldata _data) public pure returns (bytes32, bytes16) {
+        bytes32 b1;
+        bytes16 b2;
+        (b1, b2) = Sha2Ext.sha384(_data);
+        return (b1, b2);
+    }
+
+    function sha384Gas(bytes calldata _data) external returns (bytes32, bytes16) {
+        bytes32 b1;
+        bytes16 b2;
+        (b1, b2) = Sha2Ext.sha384(_data);
+        success = true;
+        return (b1, b2);
+    }
+
+    function sha256Gas(bytes calldata _data) external returns (bytes32) {
+        bytes32 b1;
+        b1 = sha256(_data);
+        success = true;
+        return (b1);
+    }
+}