Moved unused study files to studies directory

studies/comparator.sv

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+///////////////////////////////////////////
+// comparator.sv
+//
+// Written: David_Harris@hmc.edu, Sarah.Harris@unlv.edu 
+// Created: 8 December 2021
+// Modified: 
+//
+// Purpose: Branch comparison
+// 
+// Documentation: RISC-V System on Chip Design Chapter 4 (Figure 4.7)
+//
+// A component of the CORE-V-WALLY configurable RISC-V project.
+// 
+// Copyright (C) 2021-23 Harvey Mudd College & Oklahoma State University
+//
+// SPDX-License-Identifier: Apache-2.0 WITH SHL-2.1
+//
+// Licensed under the Solderpad Hardware License v 2.1 (the “License”); you may not use this file 
+// except in compliance with the License, or, at your option, the Apache License version 2.0. You 
+// may obtain a copy of the License at
+//
+// https://solderpad.org/licenses/SHL-2.1/
+//
+// Unless required by applicable law or agreed to in writing, any work distributed under the 
+// License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, 
+// either express or implied. See the License for the specific language governing permissions 
+// and limitations under the License.
+////////////////////////////////////////////////////////////////////////////////////////////////
+
+`include "wally-config.vh"
+
+// This comparator is best
+module comparator_dc_flip #(parameter WIDTH=64) (
+  input  logic [WIDTH-1:0] a, b,    // Operands
+  input  logic             sgnd,    // Signed operands
+  output logic [1:0]       flags);  // Output flags: {eq, lt}
+
+  logic             eq, lt;         // Flags: equal (eq), less than (lt)
+  logic [WIDTH-1:0] af, bf;         // Operands with msb flipped (inverted) when signed
+
+  // For signed numbers, flip most significant bit
+  assign af = {a[WIDTH-1] ^ sgnd, a[WIDTH-2:0]};
+  assign bf = {b[WIDTH-1] ^ sgnd, b[WIDTH-2:0]};
+
+  // Behavioral description gives best results
+  assign eq = (a == b);            // eq = 1 when operands are equal, 0 otherwise
+  assign lt = (af < bf);           // lt = 1 when a less than b (taking signed operands into account)
+  assign flags = {eq, lt};
+endmodule
+