1/*
2 * Copyright (c) 2001-2005 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;

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32#define __BASE__CHUNK_GENERATOR_HH__
33
34/**
35 * @file
36 * Declaration and inline definition of ChunkGenerator object.
37 */
38
39#include <algorithm>
40
41#include "base/intmath.hh"
42#include "base/types.hh"
43
44/**
45 * This class takes an arbitrary memory region (address/length pair)
46 * and generates a series of appropriately (e.g. block- or page-)
47 * aligned chunks covering the same region.
48 *
49 * Example usage:
50

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57class ChunkGenerator
58{
59 private:
60 /** The starting address of the current chunk. */
61 Addr curAddr;
62 /** The starting address of the next chunk (after the current one). */
63 Addr nextAddr;
64 /** The size of the current chunk (in bytes). */
65 unsigned curSize;
66 /** The number of bytes remaining in the region after the current chunk. */
67 unsigned sizeLeft;
68 /** The start address so we can calculate offset in writing block. */
69 const Addr startAddr;
70 /** The maximum chunk size, e.g., the cache block size or page size. */
71 const unsigned chunkSize;
72
73 public:
74 /**
75 * Constructor.
76 * @param _startAddr The starting address of the region.
77 * @param totalSize The total size of the region.
78 * @param _chunkSize The size/alignment of chunks into which
79 * the region should be decomposed.
80 */
81 ChunkGenerator(Addr _startAddr, unsigned totalSize, unsigned _chunkSize)
82 : startAddr(_startAddr), chunkSize(_chunkSize)
83 {
84 // chunkSize must be a power of two
85 assert(chunkSize == 0 || isPowerOf2(chunkSize));
86 assert(totalSize >= 0);
87
88 // set up initial chunk.
89 curAddr = startAddr;

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98 nextAddr = roundUp(startAddr, chunkSize);
99 if (curAddr == nextAddr) {
100 // ... even if startAddr is already chunk-aligned
101 nextAddr += chunkSize;
102 }
103 }
104
105 // how many bytes are left between curAddr and the end of this chunk?
106 unsigned left_in_chunk = nextAddr - curAddr;
107 curSize = std::min(totalSize, left_in_chunk);
108 sizeLeft = totalSize - curSize;
109 }
110
111 /** Return starting address of current chunk. */
112 Addr addr() const { return curAddr; }
113 /** Return size in bytes of current chunk. */
114 unsigned size() const { return curSize; }
115
116 /** Number of bytes we have already chunked up. */
117 unsigned complete() const { return curAddr - startAddr; }
118
119 /**
120 * Are we done? That is, did the last call to next() advance
121 * past the end of the region?
122 * @return True if yes, false if more to go.
123 */
124 bool done() const { return (curSize == 0); }
125
126 /**
127 * Advance generator to next chunk.
128 * @return True if successful, false if unsuccessful
129 * (because we were at the last chunk).
130 */
131 bool
132 next()
133 {
134 if (sizeLeft == 0) {
135 curSize = 0;
136 return false;
137 }
138
139 curAddr = nextAddr;
140 curSize = std::min(sizeLeft, chunkSize);
141 sizeLeft -= curSize;
142 nextAddr += curSize;
143 return true;
144 }
145};
146
147#endif // __BASE__CHUNK_GENERATOR_HH__