Merge commit '86cc97e55fe346502462284d2e636a2b3708163e' as 'Sources/OpenVPN3'

2026-04-24 00:00:05 +08:00 · 2020-02-24 14:43:11 +03:00
parent 133b3756e6 86cc97e55f
commit 32f1555929
655 changed files with 146468 additions and 0 deletions
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+//    OpenVPN -- An application to securely tunnel IP networks
+//               over a single port, with support for SSL/TLS-based
+//               session authentication and key exchange,
+//               packet encryption, packet authentication, and
+//               packet compression.
+//
+//    Copyright (C) 2012-2017 OpenVPN Inc.
+//
+//    This program is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU Affero General Public License Version 3
+//    as published by the Free Software Foundation.
+//
+//    This program is distributed in the hope that it will be useful,
+//    but WITHOUT ANY WARRANTY; without even the implied warranty of
+//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//    GNU Affero General Public License for more details.
+//
+//    You should have received a copy of the GNU Affero General Public License
+//    along with this program in the COPYING file.
+//    If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef OPENVPN_COMMON_FFS_H
+#define OPENVPN_COMMON_FFS_H
+
+// find_first_set: find the one-based position of the first 1 bit in
+// a word (scanning from least significant bit to most significant)
+
+// find_last_set: find the one-based position of the last 1 bit in
+// a word (scanning from most significant bit to least significant)
+
+namespace openvpn {
+
+#if defined(__GNUC__)
+
+  template <typename T>
+  inline constexpr int n_bits_type()
+  {
+    return sizeof(T) * 8;
+  }
+
+  template <typename T>
+  inline constexpr int n_bits_type(const T& v)
+  {
+    return sizeof(v) * 8;
+  }
+
+  inline int find_first_set(const unsigned int v)
+  {
+    if (!v)
+      return 0;
+    return __builtin_ffs(v);
+  }
+
+  inline int find_first_set(const int v)
+  {
+    return find_first_set(static_cast<unsigned int>(v));
+  }
+
+  inline int find_last_set(const unsigned int v)
+  {
+    if (!v)
+      return 0;
+    return n_bits_type(v) - __builtin_clz(v);
+  }
+
+  inline int find_last_set(const int v)
+  {
+    return find_last_set(static_cast<unsigned int>(v));
+  }
+
+  inline int find_first_set(const unsigned long v)
+  {
+    if (!v)
+      return 0;
+    return __builtin_ffsl(v);
+  }
+
+  inline int find_first_set(const long v)
+  {
+    return find_first_set(static_cast<unsigned long>(v));
+  }
+
+  inline int find_last_set(const unsigned long v)
+  {
+    if (!v)
+      return 0;
+    return n_bits_type(v) - __builtin_clzl(v);
+  }
+
+  inline int find_last_set(const long v)
+  {
+    return find_last_set(static_cast<unsigned long>(v));
+  }
+
+  inline int find_first_set(const unsigned long long v)
+  {
+    if (!v)
+      return 0;
+    return __builtin_ffsll(v);
+  }
+
+  inline int find_first_set(const long long v)
+  {
+    return find_first_set(static_cast<unsigned long long>(v));
+  }
+
+  inline int find_last_set(const unsigned long long v)
+  {
+    if (!v)
+      return 0;
+    return n_bits_type(v) - __builtin_clzll(v);
+  }
+
+  inline int find_last_set(const long long v)
+  {
+    return find_last_set(static_cast<unsigned long long>(v));
+  }
+
+#elif defined(_MSC_VER)
+
+#include <intrin.h>
+
+  inline int find_first_set(unsigned int x)
+  {
+    if (!x)
+      return 0;
+    unsigned int r = 0;
+    _BitScanForward((unsigned long *)&r, x);
+    return r + 1;
+  }
+
+  inline int find_last_set(unsigned int x)
+  {
+    if (!x)
+      return 0;
+    unsigned int r = 0;
+    _BitScanReverse((unsigned long *)&r, x);
+    return r + 1;
+  }
+
+#else
+#error no find_first_set / find_last_set implementation for this platform
+#endif
+
+  template <typename T>
+  inline bool is_pow2(const T v)
+  {
+    return v && find_first_set(v) == find_last_set(v);
+  }
+
+  template <typename T>
+  inline int log2(const T v)
+  {
+    return find_last_set(v) - 1;
+  }
+
+} // namespace openvpn
+
+#endif // OPENVPN_COMMON_FFS_H