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/**
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0.
*/
#include <aws/core/utils/stream/PreallocatedStreamBuf.h>
#include <cassert>
namespace Aws
{
namespace Utils
{
namespace Stream
{
PreallocatedStreamBuf::PreallocatedStreamBuf(unsigned char* buffer, uint64_t lengthToRead) :
m_underlyingBuffer(buffer), m_lengthToRead(lengthToRead)
{
char* end = reinterpret_cast<char*>(m_underlyingBuffer + m_lengthToRead);
char* begin = reinterpret_cast<char*>(m_underlyingBuffer);
setp(begin, end);
setg(begin, begin, end);
}
PreallocatedStreamBuf::pos_type PreallocatedStreamBuf::seekoff(off_type off, std::ios_base::seekdir dir, std::ios_base::openmode which)
{
if (dir == std::ios_base::beg)
{
return seekpos(off, which);
}
else if (dir == std::ios_base::end)
{
return seekpos(m_lengthToRead - off, which);
}
else if (dir == std::ios_base::cur)
{
if(which == std::ios_base::in)
{
return seekpos((gptr() - reinterpret_cast<char*>(m_underlyingBuffer)) + off, which);
}
else
{
return seekpos((pptr() - reinterpret_cast<char*>(m_underlyingBuffer)) + off, which);
}
}
return off_type(-1);
}
PreallocatedStreamBuf::pos_type PreallocatedStreamBuf::seekpos(pos_type pos, std::ios_base::openmode which)
{
assert(static_cast<size_t>(pos) <= m_lengthToRead);
if (static_cast<size_t>(pos) > m_lengthToRead)
{
return pos_type(off_type(-1));
}
char* end = reinterpret_cast<char*>(m_underlyingBuffer + m_lengthToRead);
char* begin = reinterpret_cast<char*>(m_underlyingBuffer);
if (which == std::ios_base::in)
{
setg(begin, begin + static_cast<size_t>(pos), end);
}
if (which == std::ios_base::out)
{
setp(begin + static_cast<size_t>(pos), end);
}
return pos;
}
}
}
}
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