timebuf.hh revision 3918 
1/*
2 * Copyright (c) 2004-2005 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;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Nathan Binkert
29 *          Kevin Lim
30 */
31
32#ifndef __BASE_TIMEBUF_HH__
33#define __BASE_TIMEBUF_HH__
34
35#include <cassert>
36#include <cstring>
37#include <vector>
38
39template <class T>
40class TimeBuffer
41{
42  protected:
43    int past;
44    int future;
45    int size;
46
47    char *data;
48    std::vector<char *> index;
49    int base;
50
51    void valid(int idx)
52    {
53        assert (idx >= -past && idx <= future);
54    }
55
56  public:
57    friend class wire;
58    class wire
59    {
60        friend class TimeBuffer;
61      protected:
62        TimeBuffer<T> *buffer;
63        int index;
64
65        void set(int idx)
66        {
67            buffer->valid(idx);
68            index = idx;
69        }
70
71        wire(TimeBuffer<T> *buf, int i)
72            : buffer(buf), index(i)
73        { }
74
75      public:
76        wire()
77        { }
78
79        wire(const wire &i)
80            : buffer(i.buffer), index(i.index)
81        { }
82
83        const wire &operator=(const wire &i)
84        {
85            buffer = i.buffer;
86            set(i.index);
87            return *this;
88        }
89
90        const wire &operator=(int idx)
91        {
92            set(idx);
93            return *this;
94        }
95
96        const wire &operator+=(int offset)
97        {
98            set(index + offset);
99            return *this;
100        }
101
102        const wire &operator-=(int offset)
103        {
104            set(index - offset);
105            return *this;
106        }
107
108        wire &operator++()
109        {
110            set(index + 1);
111            return *this;
112        }
113
114        wire &operator++(int)
115        {
116            int i = index;
117            set(index + 1);
118            return wire(this, i);
119        }
120
121        wire &operator--()
122        {
123            set(index - 1);
124            return *this;
125        }
126
127        wire &operator--(int)
128        {
129            int i = index;
130            set(index - 1);
131            return wire(this, i);
132        }
133        T &operator*() const { return *buffer->access(index); }
134        T *operator->() const { return buffer->access(index); }
135    };
136
137
138  public:
139    TimeBuffer(int p, int f)
140        : past(p), future(f), size(past + future + 1),
141          data(new char[size * sizeof(T)]), index(size), base(0)
142    {
143        assert(past >= 0 && future >= 0);
144        char *ptr = data;
145        for (int i = 0; i < size; i++) {
146            index[i] = ptr;
147            std::memset(ptr, 0, sizeof(T));
148            new (ptr) T;
149            ptr += sizeof(T);
150        }
151    }
152
153    TimeBuffer()
154        : data(NULL)
155    {
156    }
157
158    ~TimeBuffer()
159    {
160        for (int i = 0; i < size; ++i)
161            (reinterpret_cast<T *>(index[i]))->~T();
162        delete [] data;
163    }
164
165    void
166    advance()
167    {
168        if (++base >= size)
169            base = 0;
170
171        int ptr = base + future;
172        if (ptr >= size)
173            ptr -= size;
174        (reinterpret_cast<T *>(index[ptr]))->~T();
175        std::memset(index[ptr], 0, sizeof(T));
176        new (index[ptr]) T;
177    }
178
179    T *access(int idx)
180    {
181        //Need more complex math here to calculate index.
182        valid(idx);
183
184        int vector_index = idx + base;
185        if (vector_index >= size) {
186            vector_index -= size;
187        } else if (vector_index < 0) {
188            vector_index += size;
189        }
190
191        return reinterpret_cast<T *>(index[vector_index]);
192    }
193
194    T &operator[](int idx)
195    {
196        //Need more complex math here to calculate index.
197        valid(idx);
198
199        int vector_index = idx + base;
200        if (vector_index >= size) {
201            vector_index -= size;
202        } else if (vector_index < 0) {
203            vector_index += size;
204        }
205
206        return reinterpret_cast<T &>(*index[vector_index]);
207    }
208
209    wire getWire(int idx)
210    {
211        valid(idx);
212
213        return wire(this, idx);
214    }
215
216    wire zero()
217    {
218        return wire(this, 0);
219    }
220
221    int getSize()
222    {
223        return size;
224    }
225};
226
227#endif // __BASE_TIMEBUF_HH__
228
229