ByteBuffer.cpp

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/*
// $Id: //open/dev/fennel/common/ByteBuffer.cpp#7 $
// Fennel is a library of data storage and processing components.
// Copyright (C) 2005-2009 The Eigenbase Project
// Copyright (C) 2005-2009 SQLstream, Inc.
// Copyright (C) 2005-2009 LucidEra, Inc.
//
// This program is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 2 of the License, or (at your option)
// any later version approved by The Eigenbase Project.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include "fennel/common/CommonPreamble.h"
#include "fennel/common/ByteBuffer.h"

FENNEL_BEGIN_CPPFILE("$Id: //open/dev/fennel/common/ByteBuffer.cpp#7 $");
ByteBuffer::ByteBuffer()
{
    nBuffers = 0;
    bufferSize = 0;
}

void ByteBuffer::init(
    boost::shared_array<PBuffer> ppBuffers, uint nBuffers, uint bufSize)
{
    this->ppBuffers = ppBuffers;
    this->nBuffers = nBuffers;
    this->bufferSize = bufSize;

    // Currently we use bit masking (rather than mod) to calculate virtual
    // offsets. This scheme requires that the buffer size be a power of 2.
    // If this cannot be guaranteed, we should change to another scheme.
    bufferMask = bufSize - 1;
    assert((bufferMask & bufSize) == 0);

    bufferShift = 0;
    uint tmp = bufferMask;
    while (tmp > 0) {
        bufferShift++;
        tmp >>=1;
    }
}

uint ByteBuffer::getSize()
{
    return nBuffers * bufferSize;
}

void ByteBuffer::setMem(uint pos, UnsignedByte value, uint len)
{
    assert(pos + len <= getSize());
    uint current = pos;
    uint remaining = len;

    while (remaining > 0) {
        uint chunkLen;
        PBuffer mem = getMem(current, chunkLen);
        if (chunkLen >= remaining) {
            memset(mem, value, remaining);
            break;
        }
        memset(mem, value, chunkLen);
        current += chunkLen;
        remaining -= chunkLen;
    }
}

void ByteBuffer::copyMem(uint pos, PConstBuffer data, uint len)
{
    assert(pos + len <= getSize());
    uint current = pos;
    PConstBuffer currentData = data;
    uint remaining = len;

    while (remaining > 0) {
        uint chunkLen;
        PBuffer mem = getMem(current, chunkLen);
        if (chunkLen >= remaining) {
            memcpy(mem, currentData, remaining);
            break;
        }
        memcpy(mem, currentData, chunkLen);
        current += chunkLen;
        currentData += chunkLen;
        remaining -= chunkLen;
    }
}

void ByteBuffer::mergeMem(uint pos, PConstBuffer data, uint len)
{
    assert(pos + len <= getSize());
    uint current = pos;
    PConstBuffer currentData = data;
    uint remaining = len;

    while (remaining > 0) {
        uint chunkLen;
        PBuffer mem = getMem(current, chunkLen);
        if (chunkLen >= remaining) {
            memmerge(mem, currentData, remaining);
            break;
        }
        memmerge(mem, currentData, chunkLen);
        current += chunkLen;
        currentData += chunkLen;
        remaining -= chunkLen;
    }
}

FENNEL_END_CPPFILE("$Id: //open/dev/fennel/common/ByteBuffer.cpp#7 $");

// End ByteBuffer.cpp

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