Down-integrate from internal branch.

Change-Id: Ieb7a2c2fbf35bc2a8fa65b915a5ecb68c83863e4

1 files changed, 200 insertions, 0 deletions

diff --git a/src/google/protobuf/stubs/int128.cc b/src/google/protobuf/stubs/int128.cc
new file mode 100644
index 00000000..9f4fb824
--- /dev/null
+++ b/src/google/protobuf/stubs/int128.cc
@@ -0,0 +1,200 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <google/protobuf/stubs/int128.h>
+
+#include <iomanip>
+#include <iostream>  // NOLINT(readability/streams)
+#include <sstream>
+
+namespace google {
+namespace protobuf {
+
+const uint128_pod kuint128max = {
+    static_cast<uint64>(GOOGLE_LONGLONG(0xFFFFFFFFFFFFFFFF)),
+    static_cast<uint64>(GOOGLE_LONGLONG(0xFFFFFFFFFFFFFFFF))
+};
+
+// Returns the 0-based position of the last set bit (i.e., most significant bit)
+// in the given uint64. The argument may not be 0.
+//
+// For example:
+//   Given: 5 (decimal) == 101 (binary)
+//   Returns: 2
+#define STEP(T, n, pos, sh)                   \
+  do {                                        \
+    if ((n) >= (static_cast<T>(1) << (sh))) { \
+      (n) = (n) >> (sh);                      \
+      (pos) |= (sh);                          \
+    }                                         \
+  } while (0)
+static inline int Fls64(uint64 n) {
+  GOOGLE_DCHECK_NE(0, n);
+  int pos = 0;
+  STEP(uint64, n, pos, 0x20);
+  uint32 n32 = n;
+  STEP(uint32, n32, pos, 0x10);
+  STEP(uint32, n32, pos, 0x08);
+  STEP(uint32, n32, pos, 0x04);
+  return pos + ((GOOGLE_ULONGLONG(0x3333333322221100) >> (n32 << 2)) & 0x3);
+}
+#undef STEP
+
+// Like Fls64() above, but returns the 0-based position of the last set bit
+// (i.e., most significant bit) in the given uint128. The argument may not be 0.
+static inline int Fls128(uint128 n) {
+  if (uint64 hi = Uint128High64(n)) {
+    return Fls64(hi) + 64;
+  }
+  return Fls64(Uint128Low64(n));
+}
+
+// Long division/modulo for uint128 implemented using the shift-subtract
+// division algorithm adapted from:
+// http://stackoverflow.com/questions/5386377/division-without-using
+void uint128::DivModImpl(uint128 dividend, uint128 divisor,
+                         uint128* quotient_ret, uint128* remainder_ret) {
+  if (divisor == 0) {
+    GOOGLE_LOG(FATAL) << "Division or mod by zero: dividend.hi=" << dividend.hi_
+                      << ", lo=" << dividend.lo_;
+  }
+
+  if (divisor > dividend) {
+    *quotient_ret = 0;
+    *remainder_ret = dividend;
+    return;
+  }
+
+  if (divisor == dividend) {
+    *quotient_ret = 1;
+    *remainder_ret = 0;
+    return;
+  }
+
+  uint128 denominator = divisor;
+  uint128 position = 1;
+  uint128 quotient = 0;
+
+  // Left aligns the MSB of the denominator and the dividend.
+  int shift = Fls128(dividend) - Fls128(denominator);
+  denominator <<= shift;
+  position <<= shift;
+
+  // Uses shift-subtract algorithm to divide dividend by denominator. The
+  // remainder will be left in dividend.
+  while (position > 0) {
+    if (dividend >= denominator) {
+      dividend -= denominator;
+      quotient |= position;
+    }
+    position >>= 1;
+    denominator >>= 1;
+  }
+
+  *quotient_ret = quotient;
+  *remainder_ret = dividend;
+}
+
+uint128& uint128::operator/=(const uint128& divisor) {
+  uint128 quotient = 0;
+  uint128 remainder = 0;
+  DivModImpl(*this, divisor, &quotient, &remainder);
+  *this = quotient;
+  return *this;
+}
+uint128& uint128::operator%=(const uint128& divisor) {
+  uint128 quotient = 0;
+  uint128 remainder = 0;
+  DivModImpl(*this, divisor, &quotient, &remainder);
+  *this = remainder;
+  return *this;
+}
+
+std::ostream& operator<<(std::ostream& o, const uint128& b) {
+  std::ios_base::fmtflags flags = o.flags();
+
+  // Select a divisor which is the largest power of the base < 2^64.
+  uint128 div;
+  std::streamsize div_base_log;
+  switch (flags & std::ios::basefield) {
+    case std::ios::hex:
+      div = GOOGLE_ULONGLONG(0x1000000000000000);  // 16^15
+      div_base_log = 15;
+      break;
+    case std::ios::oct:
+      div = GOOGLE_ULONGLONG(01000000000000000000000);  // 8^21
+      div_base_log = 21;
+      break;
+    default:  // std::ios::dec
+      div = GOOGLE_ULONGLONG(10000000000000000000);  // 10^19
+      div_base_log = 19;
+      break;
+  }
+
+  // Now piece together the uint128 representation from three chunks of
+  // the original value, each less than "div" and therefore representable
+  // as a uint64.
+  std::ostringstream os;
+  std::ios_base::fmtflags copy_mask =
+      std::ios::basefield | std::ios::showbase | std::ios::uppercase;
+  os.setf(flags & copy_mask, copy_mask);
+  uint128 high = b;
+  uint128 low;
+  uint128::DivModImpl(high, div, &high, &low);
+  uint128 mid;
+  uint128::DivModImpl(high, div, &high, &mid);
+  if (high.lo_ != 0) {
+    os << high.lo_;
+    os << std::noshowbase << std::setfill('0') << std::setw(div_base_log);
+    os << mid.lo_;
+    os << std::setw(div_base_log);
+  } else if (mid.lo_ != 0) {
+    os << mid.lo_;
+    os << std::noshowbase << std::setfill('0') << std::setw(div_base_log);
+  }
+  os << low.lo_;
+  std::string rep = os.str();
+
+  // Add the requisite padding.
+  std::streamsize width = o.width(0);
+  if (width > rep.size()) {
+    if ((flags & std::ios::adjustfield) == std::ios::left) {
+      rep.append(width - rep.size(), o.fill());
+    } else {
+      rep.insert(0, width - rep.size(), o.fill());
+    }
+  }
+
+  // Stream the final representation in a single "<<" call.
+  return o << rep;
+}
+
+}  // namespace protobuf
+}  // namespace google