charbuf.cpp

/******************************************************************************
* Copyright (c) 2014, Hobu Inc.
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*       names of its contributors may be used to endorse or promote
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*       written permission.
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#include "charbuf.hpp"

namespace lazperf
{

void charbuf::initialize(char *buf, size_t count, std::ios::pos_type bufOffset)
{
    m_bufOffset = bufOffset;
    m_buf = buf;
    setg(buf, buf, buf + count);
    setp(buf, buf + count);
}


std::ios::pos_type charbuf::seekpos(std::ios::pos_type pos,
    std::ios_base::openmode which)
{
    pos -= m_bufOffset;
    if (which & std::ios_base::in)
    {
        if (pos >= egptr() - eback())
            return -1;
        char *cpos = eback() + pos;
        setg(eback(), cpos, egptr());
    }
    if (which & std::ios_base::out)
    {
        if (pos > epptr() - m_buf)
            return -1;
        char *cpos = m_buf + pos;
        setp(cpos, epptr());
    }
    return pos;
}

std::ios::pos_type
charbuf::seekoff(std::ios::off_type off, std::ios_base::seekdir dir,
    std::ios_base::openmode which)
{
    std::ios::pos_type pos;
    char *cpos = nullptr;
    if (which & std::ios_base::in)
    {
        switch (dir)
        {
        case std::ios::beg:
            cpos = eback() + off - m_bufOffset;
            break;
        case std::ios::cur:
            cpos = gptr() + off;
            break;
        case std::ios::end:
            cpos = egptr() - off;
            break;
        default:
            break;  // Should never happen.
        }
        if (cpos < eback() || cpos > egptr())
            return -1;
        setg(eback(), cpos, egptr());
        pos = cpos - eback();
    }
    if (which & std::ios_base::out)
    {
        switch (dir)
        {
        case std::ios::beg:
            cpos = m_buf + off - m_bufOffset;
            break;
        case std::ios::cur:
            cpos = pptr() + off;
            break;
        case std::ios::end:
            cpos = egptr() - off;
            break;
        default:
            break;  // Should never happen.
        }
        if (cpos < m_buf || cpos > epptr())
            return -1;
        setp(cpos, epptr());
        pos = cpos - m_buf;
    }
    return pos;
}

} //namespace lazperf