timebuf.hh revision 2989 
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 <vector>
37
38template <class T>
39class TimeBuffer
40{
41  protected:
42    int past;
43    int future;
44    int size;
45
46    char *data;
47    std::vector<char *> index;
48    int base;
49
50    void valid(int idx)
51    {
52        assert (idx >= -past && idx <= future);
53    }
54
55  public:
56    friend class wire;
57    class wire
58    {
59        friend class TimeBuffer;
60      protected:
61        TimeBuffer<T> *buffer;
62        int index;
63
64        void set(int idx)
65        {
66            buffer->valid(idx);
67            index = idx;
68        }
69
70        wire(TimeBuffer<T> *buf, int i)
71            : buffer(buf), index(i)
72        { }
73
74      public:
75        wire()
76        { }
77
78        wire(const wire &i)
79            : buffer(i.buffer), index(i.index)
80        { }
81
82        const wire &operator=(const wire &i)
83        {
84            buffer = i.buffer;
85            set(i.index);
86            return *this;
87        }
88
89        const wire &operator=(int idx)
90        {
91            set(idx);
92            return *this;
93        }
94
95        const wire &operator+=(int offset)
96        {
97            set(index + offset);
98            return *this;
99        }
100
101        const wire &operator-=(int offset)
102        {
103            set(index - offset);
104            return *this;
105        }
106
107        wire &operator++()
108        {
109            set(index + 1);
110            return *this;
111        }
112
113        wire &operator++(int)
114        {
115            int i = index;
116            set(index + 1);
117            return wire(this, i);
118        }
119
120        wire &operator--()
121        {
122            set(index - 1);
123            return *this;
124        }
125
126        wire &operator--(int)
127        {
128            int i = index;
129            set(index - 1);
130            return wire(this, i);
131        }
132        T &operator*() const { return *buffer->access(index); }
133        T *operator->() const { return buffer->access(index); }
134    };
135
136
137  public:
138    TimeBuffer(int p, int f)
139        : past(p), future(f), size(past + future + 1),
140          data(new char[size * sizeof(T)]), index(size), base(0)
141    {
142        assert(past >= 0 && future >= 0);
143        char *ptr = data;
144        for (int i = 0; i < size; i++) {
145            index[i] = ptr;
146            memset(ptr, 0, sizeof(T));
147            new (ptr) T;
148            ptr += sizeof(T);
149        }
150    }
151
152    TimeBuffer()
153        : data(NULL)
154    {
155    }
156
157    ~TimeBuffer()
158    {
159        for (int i = 0; i < size; ++i)
160            (reinterpret_cast<T *>(index[i]))->~T();
161        delete [] data;
162    }
163
164    void
165    advance()
166    {
167        if (++base >= size)
168            base = 0;
169
170        int ptr = base + future;
171        if (ptr >= size)
172            ptr -= size;
173        (reinterpret_cast<T *>(index[ptr]))->~T();
174        memset(index[ptr], 0, sizeof(T));
175        new (index[ptr]) T;
176    }
177
178    T *access(int idx)
179    {
180        //Need more complex math here to calculate index.
181        valid(idx);
182
183        int vector_index = idx + base;
184        if (vector_index >= size) {
185            vector_index -= size;
186        } else if (vector_index < 0) {
187            vector_index += size;
188        }
189
190        return reinterpret_cast<T *>(index[vector_index]);
191    }
192
193    T &operator[](int idx)
194    {
195        //Need more complex math here to calculate index.
196        valid(idx);
197
198        int vector_index = idx + base;
199        if (vector_index >= size) {
200            vector_index -= size;
201        } else if (vector_index < 0) {
202            vector_index += size;
203        }
204
205        return reinterpret_cast<T &>(*index[vector_index]);
206    }
207
208    wire getWire(int idx)
209    {
210        valid(idx);
211
212        return wire(this, idx);
213    }
214
215    wire zero()
216    {
217        return wire(this, 0);
218    }
219
220    int getSize()
221    {
222        return size;
223    }
224};
225
226#endif // __BASE_TIMEBUF_HH__
227
228