initial commit

tdutils/td/utils/bits.h

@@ -0,0 +1,267 @@
+/*
+    This file is part of TON Blockchain Library.
+
+    TON Blockchain Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    TON Blockchain Library 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 Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2017-2019 Telegram Systems LLP
+*/
+#pragma once
+
+#include "td/utils/common.h"
+
+#if TD_MSVC
+#include <intrin.h>
+#endif
+
+#ifdef bswap32
+#undef bswap32
+#endif
+
+#ifdef bswap64
+#undef bswap64
+#endif
+
+namespace td {
+
+int32 count_leading_zeroes32(uint32 x);
+int32 count_leading_zeroes64(uint64 x);
+int32 count_trailing_zeroes32(uint32 x);
+int32 count_trailing_zeroes64(uint64 x);
+uint32 bswap32(uint32 x);
+uint64 bswap64(uint64 x);
+int32 count_bits32(uint32 x);
+int32 count_bits64(uint64 x);
+
+inline uint32 bits_negate32(uint32 x) {
+  return ~x + 1;
+}
+
+inline uint64 bits_negate64(uint64 x) {
+  return ~x + 1;
+}
+
+inline uint32 lower_bit32(uint32 x) {
+  return x & bits_negate32(x);
+}
+
+inline uint64 lower_bit64(uint64 x) {
+  return x & bits_negate64(x);
+}
+
+//TODO: optimize
+inline int32 count_leading_zeroes_non_zero32(uint32 x) {
+  DCHECK(x != 0);
+  return count_leading_zeroes32(x);
+}
+inline int32 count_leading_zeroes_non_zero64(uint64 x) {
+  DCHECK(x != 0);
+  return count_leading_zeroes64(x);
+}
+inline int32 count_trailing_zeroes_non_zero32(uint32 x) {
+  DCHECK(x != 0);
+  return count_trailing_zeroes32(x);
+}
+inline int32 count_trailing_zeroes_non_zero64(uint64 x) {
+  DCHECK(x != 0);
+  return count_trailing_zeroes64(x);
+}
+
+//
+// Platform specific implementation
+//
+#if TD_MSVC
+
+inline int32 count_leading_zeroes32(uint32 x) {
+  unsigned long res = 0;
+  if (_BitScanReverse(&res, x)) {
+    return 31 - res;
+  }
+  return 32;
+}
+
+inline int32 count_leading_zeroes64(uint64 x) {
+#if defined(_M_X64)
+  unsigned long res = 0;
+  if (_BitScanReverse64(&res, x)) {
+    return 63 - res;
+  }
+  return 64;
+#else
+  if ((x >> 32) == 0) {
+    return count_leading_zeroes32(static_cast<uint32>(x)) + 32;
+  } else {
+    return count_leading_zeroes32(static_cast<uint32>(x >> 32));
+  }
+#endif
+}
+
+inline int32 count_trailing_zeroes32(uint32 x) {
+  unsigned long res = 0;
+  if (_BitScanForward(&res, x)) {
+    return res;
+  }
+  return 32;
+}
+
+inline int32 count_trailing_zeroes64(uint64 x) {
+#if defined(_M_X64)
+  unsigned long res = 0;
+  if (_BitScanForward64(&res, x)) {
+    return res;
+  }
+  return 64;
+#else
+  if (static_cast<uint32>(x) == 0) {
+    return count_trailing_zeroes32(static_cast<uint32>(x >> 32)) + 32;
+  } else {
+    return count_trailing_zeroes32(static_cast<uint32>(x));
+  }
+#endif
+}
+
+inline uint32 bswap32(uint32 x) {
+  return _byteswap_ulong(x);
+}
+
+inline uint64 bswap64(uint64 x) {
+  return _byteswap_uint64(x);
+}
+
+inline int32 count_bits32(uint32 x) {
+  return __popcnt(x);
+}
+
+inline int32 count_bits64(uint64 x) {
+#if defined(_M_X64)
+  return static_cast<int32>(__popcnt64(x));
+#else
+  return count_bits32(static_cast<uint32>(x >> 32)) + count_bits32(static_cast<uint32>(x));
+#endif
+}
+
+#elif TD_INTEL
+
+inline int32 count_leading_zeroes32(uint32 x) {
+  unsigned __int32 res = 0;
+  if (_BitScanReverse(&res, x)) {
+    return 31 - res;
+  }
+  return 32;
+}
+
+inline int32 count_leading_zeroes64(uint64 x) {
+#if defined(_M_X64) || defined(__x86_64__)
+  unsigned __int32 res = 0;
+  if (_BitScanReverse64(&res, x)) {
+    return 63 - res;
+  }
+  return 64;
+#else
+  if ((x >> 32) == 0) {
+    return count_leading_zeroes32(static_cast<uint32>(x)) + 32;
+  } else {
+    return count_leading_zeroes32(static_cast<uint32>(x >> 32));
+  }
+#endif
+}
+
+inline int32 count_trailing_zeroes32(uint32 x) {
+  unsigned __int32 res = 0;
+  if (_BitScanForward(&res, x)) {
+    return res;
+  }
+  return 32;
+}
+
+inline int32 count_trailing_zeroes64(uint64 x) {
+#if defined(_M_X64) || defined(__x86_64__)
+  unsigned __int32 res = 0;
+  if (_BitScanForward64(&res, x)) {
+    return res;
+  }
+  return 64;
+#else
+  if (static_cast<uint32>(x) == 0) {
+    return count_trailing_zeroes32(static_cast<uint32>(x >> 32)) + 32;
+  } else {
+    return count_trailing_zeroes32(static_cast<uint32>(x));
+  }
+#endif
+}
+
+inline uint32 bswap32(uint32 x) {
+  return _bswap(static_cast<int>(x));
+}
+
+inline uint64 bswap64(uint64 x) {
+  return _bswap64(static_cast<__int64>(x));
+}
+
+inline int32 count_bits32(uint32 x) {
+  return _popcnt32(static_cast<int>(x));
+}
+
+inline int32 count_bits64(uint64 x) {
+  return _popcnt64(static_cast<__int64>(x));
+}
+
+#else
+
+inline int32 count_leading_zeroes32(uint32 x) {
+  if (x == 0) {
+    return 32;
+  }
+  return __builtin_clz(x);
+}
+
+inline int32 count_leading_zeroes64(uint64 x) {
+  if (x == 0) {
+    return 64;
+  }
+  return __builtin_clzll(x);
+}
+
+inline int32 count_trailing_zeroes32(uint32 x) {
+  if (x == 0) {
+    return 32;
+  }
+  return __builtin_ctz(x);
+}
+
+inline int32 count_trailing_zeroes64(uint64 x) {
+  if (x == 0) {
+    return 64;
+  }
+  return __builtin_ctzll(x);
+}
+
+inline uint32 bswap32(uint32 x) {
+  return __builtin_bswap32(x);
+}
+
+inline uint64 bswap64(uint64 x) {
+  return __builtin_bswap64(x);
+}
+
+inline int32 count_bits32(uint32 x) {
+  return __builtin_popcount(x);
+}
+
+inline int32 count_bits64(uint64 x) {
+  return __builtin_popcountll(x);
+}
+
+#endif
+
+}  // namespace td