[x64] Add `x64_util.h`

Used to help with generating instruction-specific constants.  Currently
used for the ternary-logic constants(`vpternlog*`).

src/xenia/cpu/backend/x64/x64_util.h

@@ -0,0 +1,46 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2022 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#ifndef XENIA_CPU_BACKEND_X64_X64_UTIL_H_
+#define XENIA_CPU_BACKEND_X64_X64_UTIL_H_
+
+#include "xenia/base/vec128.h"
+#include "xenia/cpu/backend/x64/x64_backend.h"
+#include "xenia/cpu/backend/x64/x64_emitter.h"
+
+namespace xe {
+namespace cpu {
+namespace backend {
+namespace x64 {
+
+// Used to generate ternary logic truth-tables for vpternlog
+// Use these to directly refer to terms and perform binary operations upon them
+// and the resulting value will be the ternary lookup table
+// ex:
+//  (TernaryOperand::a | ~TernaryOperand::b) & TernaryOperand::c
+//      = 0b10100010
+//      = 0xa2
+//  vpternlog a, b, c, 0xa2
+//
+//  ~(TernaryOperand::a ^ TernaryOperand::b) & TernaryOperand::c
+//      = 0b10000010
+//      = 0x82
+//  vpternlog a, b, c, 0x82
+namespace TernaryOperand {
+constexpr uint8_t a = 0b11110000;
+constexpr uint8_t b = 0b11001100;
+constexpr uint8_t c = 0b10101010;
+}  // namespace TernaryOperand
+
+}  // namespace x64
+}  // namespace backend
+}  // namespace cpu
+}  // namespace xe
+
+#endif  // XENIA_CPU_BACKEND_X64_X64_UTIL_H_