Adding code. Closes #0.

include/internal/bit_utils.h

@@ -0,0 +1,39 @@
+// Copyright 2017 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// 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.
+
+#ifndef THIRD_PARTY_CPU_FEATURES_INCLUDE_INTERNAL_BIT_UTILS_H_
+#define THIRD_PARTY_CPU_FEATURES_INCLUDE_INTERNAL_BIT_UTILS_H_
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include "cpu_features_macros.h"
+
+START_CPP_NAMESPACE
+
+inline static bool IsBitSet(uint32_t reg, uint32_t bit) {
+  return (reg >> bit) & 0x1;
+}
+
+inline static uint32_t ExtractBitRange(uint32_t reg, uint32_t msb,
+                                       uint32_t lsb) {
+  const uint64_t bits = msb - lsb + 1;
+  const uint64_t mask = (1ULL << bits) - 1ULL;
+  assert(msb >= lsb);
+  return (reg >> lsb) & mask;
+}
+
+END_CPP_NAMESPACE
+
+#endif  // THIRD_PARTY_CPU_FEATURES_INCLUDE_INTERNAL_BIT_UTILS_H_