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#pragma once
#include <base/types.h>
#include <base/defines.h>
#include <IO/ReadBuffer.h>
#include <IO/WriteBuffer.h>
namespace DB
{
/// Variable-Length Quantity (VLQ) Base-128 compression, also known as Variable Byte (VB) or Varint encoding.
[[noreturn]] void throwReadAfterEOF();
inline void writeVarUInt(UInt64 x, WriteBuffer & ostr)
{
while (x > 0x7F)
{
uint8_t byte = 0x80 | (x & 0x7F);
ostr.nextIfAtEnd();
*ostr.position() = byte;
++ostr.position();
x >>= 7;
}
uint8_t final_byte = static_cast<uint8_t>(x);
ostr.nextIfAtEnd();
*ostr.position() = final_byte;
++ostr.position();
}
inline void writeVarUInt(UInt64 x, std::ostream & ostr)
{
while (x > 0x7F)
{
uint8_t byte = 0x80 | (x & 0x7F);
ostr.put(byte);
x >>= 7;
}
uint8_t final_byte = static_cast<uint8_t>(x);
ostr.put(final_byte);
}
inline char * writeVarUInt(UInt64 x, char * ostr)
{
while (x > 0x7F)
{
uint8_t byte = 0x80 | (x & 0x7F);
*ostr = byte;
++ostr;
x >>= 7;
}
uint8_t final_byte = static_cast<uint8_t>(x);
*ostr = final_byte;
++ostr;
return ostr;
}
template <typename Out>
inline void writeVarInt(Int64 x, Out & ostr)
{
writeVarUInt(static_cast<UInt64>((x << 1) ^ (x >> 63)), ostr);
}
inline char * writeVarInt(Int64 x, char * ostr)
{
return writeVarUInt(static_cast<UInt64>((x << 1) ^ (x >> 63)), ostr);
}
namespace impl
{
template <bool check_eof>
inline void readVarUInt(UInt64 & x, ReadBuffer & istr)
{
x = 0;
for (size_t i = 0; i < 10; ++i)
{
if constexpr (check_eof)
if (istr.eof()) [[unlikely]]
throwReadAfterEOF();
UInt64 byte = *istr.position();
++istr.position();
x |= (byte & 0x7F) << (7 * i);
if (!(byte & 0x80))
return;
}
}
}
inline void readVarUInt(UInt64 & x, ReadBuffer & istr)
{
if (istr.buffer().end() - istr.position() >= 10)
return impl::readVarUInt<false>(x, istr);
return impl::readVarUInt<true>(x, istr);
}
inline void readVarUInt(UInt64 & x, std::istream & istr)
{
x = 0;
for (size_t i = 0; i < 10; ++i)
{
UInt64 byte = istr.get();
x |= (byte & 0x7F) << (7 * i);
if (!(byte & 0x80))
return;
}
}
inline const char * readVarUInt(UInt64 & x, const char * istr, size_t size)
{
const char * end = istr + size;
x = 0;
for (size_t i = 0; i < 10; ++i)
{
if (istr == end) [[unlikely]]
throwReadAfterEOF();
UInt64 byte = *istr;
++istr;
x |= (byte & 0x7F) << (7 * i);
if (!(byte & 0x80))
return istr;
}
return istr;
}
template <typename In>
inline void readVarInt(Int64 & x, In & istr)
{
readVarUInt(*reinterpret_cast<UInt64*>(&x), istr);
x = (static_cast<UInt64>(x) >> 1) ^ -(x & 1);
}
inline const char * readVarInt(Int64 & x, const char * istr, size_t size)
{
const char * res = readVarUInt(*reinterpret_cast<UInt64*>(&x), istr, size);
x = (static_cast<UInt64>(x) >> 1) ^ -(x & 1);
return res;
}
inline void readVarUInt(UInt32 & x, ReadBuffer & istr)
{
UInt64 tmp;
readVarUInt(tmp, istr);
x = static_cast<UInt32>(tmp);
}
inline void readVarInt(Int32 & x, ReadBuffer & istr)
{
Int64 tmp;
readVarInt(tmp, istr);
x = static_cast<Int32>(tmp);
}
inline void readVarUInt(UInt16 & x, ReadBuffer & istr)
{
UInt64 tmp;
readVarUInt(tmp, istr);
x = tmp;
}
inline void readVarInt(Int16 & x, ReadBuffer & istr)
{
Int64 tmp;
readVarInt(tmp, istr);
x = tmp;
}
template <typename T>
requires (!std::is_same_v<T, UInt64>)
inline void readVarUInt(T & x, ReadBuffer & istr)
{
UInt64 tmp;
readVarUInt(tmp, istr);
x = tmp;
}
inline size_t getLengthOfVarUInt(UInt64 x)
{
return x < (1ULL << 7) ? 1
: (x < (1ULL << 14) ? 2
: (x < (1ULL << 21) ? 3
: (x < (1ULL << 28) ? 4
: (x < (1ULL << 35) ? 5
: (x < (1ULL << 42) ? 6
: (x < (1ULL << 49) ? 7
: (x < (1ULL << 56) ? 8
: (x < (1ULL << 63) ? 9
: 10))))))));
}
inline size_t getLengthOfVarInt(Int64 x)
{
return getLengthOfVarUInt(static_cast<UInt64>((x << 1) ^ (x >> 63)));
}
}
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