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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.
*/
#ifndef __BASE_CHUNK_GENERATOR_HH__
#define __BASE_CHUNK_GENERATOR_HH__
/**
* @file
* Declaration and inline definition of ChunkGenerator object.
*/
#include <algorithm>
#include <cassert>
#include "base/intmath.hh"
#include "base/types.hh"
namespace gem5
{
/**
* 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). */
Addr curSize;
/** The size of the next chunk (in bytes). */
Addr nextSize;
/** The number of bytes remaining in the region after the current chunk. */
Addr 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 Addr 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.
*
* @ingroup api_chunk_generator
*/
ChunkGenerator(Addr _startAddr, Addr totalSize, Addr _chunkSize) :
startAddr(_startAddr), chunkSize(_chunkSize)
{
// chunkSize must be a power of two
assert(chunkSize == 0 || isPowerOf2(chunkSize));
// set up initial chunk.
curAddr = startAddr;
if (chunkSize == 0) { // Special Case, if we see 0, assume no chunking.
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;
}
nextAddr = std::min(nextAddr, startAddr + totalSize);
}
// How many bytes are left between curAddr and the end of this chunk?
curSize = nextAddr - curAddr;
sizeLeft = totalSize - curSize;
nextSize = std::min(sizeLeft, chunkSize);
}
/**
* Return starting address of current chunk.
*
* @ingroup api_chunk_generator
*/
Addr addr() const { return curAddr; }
/**
* Return size in bytes of current chunk.
*
* @ingroup api_chunk_generator
*/
Addr size() const { return curSize; }
/**
* Number of bytes we have already chunked up.
*
* @ingroup api_chunk_generator
*/
Addr 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.
*
* @ingroup api_chunk_generator
*/
bool done() const { return curSize == 0; }
/**
* Is this the last chunk?
* @return True if yes, false if more to go.
*
* @ingroup api_chunk_generator
*/
bool last() const { return sizeLeft == 0; }
/**
* Grow this chunk to cover additional bytes which are already handled.
* @param next The first byte of the next chunk.
*
* @ingroup api_chunk_generator
*/
void
setNext(Addr next)
{
assert(next >= nextAddr);
const Addr skipping = std::min(next - nextAddr, sizeLeft);
sizeLeft -= skipping;
curSize += skipping;
nextAddr = next;
assert(chunkSize);
// nextSize will be enough to get to an alignment boundary,
nextSize = roundUp(next, chunkSize) - next;
// or if it's already aligned, to the following boundary or the end.
if (!nextSize)
nextSize = std::min(sizeLeft, chunkSize);
}
/**
* Advance generator to next chunk.
* @return True if successful, false if unsuccessful
* (because we were at the last chunk).
*
* @ingroup api_chunk_generator
*/
bool
next()
{
if (last()) {
curSize = 0;
return false;
}
curAddr = nextAddr;
curSize = nextSize;
sizeLeft -= curSize;
nextAddr += curSize;
nextSize = std::min(sizeLeft, chunkSize);
return true;
}
};
} // namespace gem5
#endif // __BASE_CHUNK_GENERATOR_HH__