[NFC][HW] Add container class for n-valued logic constants

include/circt/Dialect/HW/HWLogicDigits.h

@@ -0,0 +1,128 @@
+//===- HWLogicDigits.h - Primitives for 9-valued logic ----------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the binary encoding for multi-valued logic primitives and
+// operations. The set of valid digits is equivalent to the 9-valued logic
+// of the IEEE 1164 standard. However, their specific semantics may differ
+// depending on the context.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef CIRCT_DIALECT_HW_HWLOGICDIGITS_H
+#define CIRCT_DIALECT_HW_HWLOGICDIGITS_H
+
+#include "llvm/Support/ErrorHandling.h"
+
+#include <stdint.h>
+
+namespace circt {
+namespace hw {
+namespace logicdigits {
+
+/// Logic digit primitives
+enum LogicDigit : uint8_t {
+  Invalid = 0, // Guard value, not an actual digit
+  LD_U = 1,
+  LD_X = 2,
+  LD_0 = 3,
+  LD_1 = 4,
+  LD_Z = 5,
+  LD_W = 6,
+  LD_L = 7,
+  LD_H = 8,
+  LD_DC = 9 // Don't-care '-'
+};
+
+/// LUT type for unary logic operations
+using UnaryLogicLUT = LogicDigit[10];
+/// LUT type for binary logic operations
+using BinaryLogicLUT = UnaryLogicLUT[10];
+
+/// Returns true if the given digit is a valid 9-valued logic digit
+inline constexpr bool isValidLogicDigit(LogicDigit digit) {
+  return (digit != LogicDigit::Invalid) && (digit <= LogicDigit::LD_DC);
+}
+
+/// Convert a (uppercase) character to its matching 9-valued logic digit
+inline constexpr LogicDigit charToLogicDigit(char c) {
+  switch (c) {
+  case 'U':
+    return LogicDigit::LD_U;
+  case 'X':
+    return LogicDigit::LD_X;
+  case '0':
+    return LogicDigit::LD_0;
+  case '1':
+    return LogicDigit::LD_1;
+  case 'Z':
+    return LogicDigit::LD_Z;
+  case 'W':
+    return LogicDigit::LD_W;
+  case 'L':
+    return LogicDigit::LD_L;
+  case 'H':
+    return LogicDigit::LD_H;
+  case '-':
+    return LogicDigit::LD_DC;
+  default:
+    return LogicDigit::Invalid;
+  }
+};
+
+/// Convert a binary-encoded 9-valued logic digit to a human readable character
+inline constexpr char logicDigitToChar(LogicDigit ld) {
+  switch (ld) {
+  case Invalid:
+    return '#';
+  case LD_U:
+    return 'U';
+  case LD_X:
+    return 'X';
+  case LD_0:
+    return '0';
+  case LD_1:
+    return '1';
+  case LD_Z:
+    return 'Z';
+  case LD_W:
+    return 'W';
+  case LD_L:
+    return 'L';
+  case LD_H:
+    return 'H';
+  case LD_DC:
+    return '-';
+  }
+  llvm_unreachable("logic digit not an enum value");
+}
+
+// --------------
+// IEEE1164 LUTs
+// --------------
+
+/// IEEE1164 XOR operation
+static constexpr BinaryLogicLUT lutIeee1164Xor = {
+    {Invalid, Invalid, Invalid, Invalid, Invalid, Invalid, Invalid, Invalid,
+     Invalid, Invalid},
+    {Invalid, LD_U, LD_U, LD_U, LD_U, LD_U, LD_U, LD_U, LD_U, LD_U},
+    {Invalid, LD_U, LD_X, LD_X, LD_X, LD_X, LD_X, LD_X, LD_X, LD_X},
+    {Invalid, LD_U, LD_X, LD_0, LD_1, LD_X, LD_X, LD_0, LD_1, LD_X},
+    {Invalid, LD_U, LD_X, LD_1, LD_0, LD_X, LD_X, LD_1, LD_0, LD_X},
+    {Invalid, LD_U, LD_X, LD_X, LD_X, LD_X, LD_X, LD_X, LD_X, LD_X},
+    {Invalid, LD_U, LD_X, LD_X, LD_X, LD_X, LD_X, LD_X, LD_X, LD_X},
+    {Invalid, LD_U, LD_X, LD_0, LD_1, LD_X, LD_X, LD_0, LD_1, LD_X},
+    {Invalid, LD_U, LD_X, LD_1, LD_0, LD_X, LD_X, LD_1, LD_0, LD_X},
+    {Invalid, LD_U, LD_X, LD_X, LD_X, LD_X, LD_X, LD_X, LD_X, LD_X}};
+
+// TODO: Add other operations
+
+} // namespace logicdigits
+} // namespace hw
+} // namespace circt
+
+#endif // CIRCT_DIALECT_HW_HWLOGICDIGITS_H