// 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 <ostream> // 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, "ient, &remainder);
*this = quotient;
return *this;
}
uint128& uint128::operator%=(const uint128& divisor) {
uint128 quotient = 0;
uint128 remainder = 0;
DivModImpl(*this, divisor, "ient, &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 = static_cast<uint64>(GOOGLE_ULONGLONG(0x1000000000000000)); // 16^15
div_base_log = 15;
break;
case std::ios::oct:
div = static_cast<uint64>(GOOGLE_ULONGLONG(01000000000000000000000)); // 8^21
div_base_log = 21;
break;
default: // std::ios::dec
div = static_cast<uint64>(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(static_cast<std::string::size_type>(0),
width - rep.size(), o.fill());
}
}
// Stream the final representation in a single "<<" call.
return o << rep;
}
} // namespace protobuf
} // namespace google
