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/*
* Copyright (c) 2001-2005 The Regents of The University of Michigan
* All rights reserved.
*
* 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 the copyright holders 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.
*
* Authors: Steve Reinhardt
*/
#ifndef __BASE__CHUNK_GENERATOR_HH__
#define __BASE__CHUNK_GENERATOR_HH__
/**
* @file
* Declaration and inline definition of ChunkGenerator object.
*/
#include <algorithm>
#include "base/intmath.hh"
#include "base/types.hh"
/**
* This class takes an arbitrary memory region (address/length pair)
* and generates a series of appropriately (e.g. block- or page-)
* aligned chunks covering the same region.
*
* Example usage:
\code
for (ChunkGenerator gen(addr, size, chunkSize); !gen.done(); gen.next()) {
doSomethingChunky(gen.addr(), gen.size());
}
\endcode
*/
class ChunkGenerator
{
private:
/** The starting address of the current chunk. */
Addr curAddr;
/** The starting address of the next chunk (after the current one). */
Addr nextAddr;
/** The size of the current chunk (in bytes). */
unsigned curSize;
/** The number of bytes remaining in the region after the current chunk. */
unsigned sizeLeft;
/** The start address so we can calculate offset in writing block. */
const Addr startAddr;
/** The maximum chunk size, e.g., the cache block size or page size. */
const unsigned chunkSize;
public:
/**
* Constructor.
* @param _startAddr The starting address of the region.
* @param totalSize The total size of the region.
* @param _chunkSize The size/alignment of chunks into which
* the region should be decomposed.
*/
ChunkGenerator(Addr _startAddr, unsigned totalSize, unsigned _chunkSize)
: startAddr(_startAddr), chunkSize(_chunkSize)
{
// chunkSize must be a power of two
assert(chunkSize == 0 || isPowerOf2(chunkSize));
assert(totalSize >= 0);
// set up initial chunk.
curAddr = startAddr;
if (chunkSize == 0) //Special Case, if we see 0, assume no chuncking
{
nextAddr = startAddr + totalSize;
}
else
{
// nextAddr should be *next* chunk start
nextAddr = roundUp(startAddr, chunkSize);
if (curAddr == nextAddr) {
// ... even if startAddr is already chunk-aligned
nextAddr += chunkSize;
}
}
// how many bytes are left between curAddr and the end of this chunk?
unsigned left_in_chunk = nextAddr - curAddr;
curSize = std::min(totalSize, left_in_chunk);
sizeLeft = totalSize - curSize;
}
/** Return starting address of current chunk. */
Addr addr() const { return curAddr; }
/** Return size in bytes of current chunk. */
unsigned size() const { return curSize; }
/** Number of bytes we have already chunked up. */
unsigned complete() const { return curAddr - startAddr; }
/**
* Are we done? That is, did the last call to next() advance
* past the end of the region?
* @return True if yes, false if more to go.
*/
bool done() const { return (curSize == 0); }
/**
* Advance generator to next chunk.
* @return True if successful, false if unsuccessful
* (because we were at the last chunk).
*/
bool
next()
{
if (sizeLeft == 0) {
curSize = 0;
return false;
}
curAddr = nextAddr;
curSize = std::min(sizeLeft, chunkSize);
sizeLeft -= curSize;
nextAddr += curSize;
return true;
}
};
#endif // __BASE__CHUNK_GENERATOR_HH__
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