From dce0c77ca296228958d14f6a087cb563ae52997b Mon Sep 17 00:00:00 2001 From: Steve Reinhardt Date: Fri, 23 Dec 2005 14:06:27 -0500 Subject: [PATCH] Add ChunkGenerator object for breaking arbitrary regions into block- or page-sized chunks. --HG-- extra : convert_revision : 3ebdd496f9ffc6d1fcd1847c33e98ac23f1bfe66 --- base/chunk_generator.hh | 130 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 130 insertions(+) create mode 100644 base/chunk_generator.hh diff --git a/base/chunk_generator.hh b/base/chunk_generator.hh new file mode 100644 index 000000000..83caaca88 --- /dev/null +++ b/base/chunk_generator.hh @@ -0,0 +1,130 @@ +/* + * 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 +#include "base/intmath.hh" +#include "targetarch/isa_traits.hh" // for Addr + +/** + * 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). */ + int curSize; + /** The number of bytes remaining in the region after the current chunk. */ + int sizeLeft; + /** The maximum chunk size, e.g., the cache block size or page size. */ + const int 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, int totalSize, int _chunkSize) + : chunkSize(_chunkSize) + { + // chunkSize must be a power of two + assert(isPowerOf2(chunkSize)); + + // set up initial chunk. + curAddr = startAddr; + + // 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? + int left_in_chunk = nextAddr - curAddr; + curSize = std::min(totalSize, left_in_chunk); + sizeLeft = totalSize - curSize; + } + + /** Return starting address of current chunk. */ + Addr addr() { return curAddr; } + /** Return size in bytes of current chunk. */ + int size() { return curSize; } + + /** + * 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() { 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__ -- 2.30.2