timebuf.hh revision 2291 
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
29#ifndef __BASE_TIMEBUF_HH__
30#define __BASE_TIMEBUF_HH__
31
32#include <vector>
33
34template <class T>
35class TimeBuffer
36{
37  protected:
38    int past;
39    int future;
40    int size;
41
42    char *data;
43    std::vector<char *> index;
44    int base;
45
46    void valid(int idx)
47    {
48        assert (idx >= -past && idx <= future);
49    }
50
51  public:
52    friend class wire;
53    class wire
54    {
55        friend class TimeBuffer;
56      protected:
57        TimeBuffer<T> *buffer;
58        int index;
59
60        void set(int idx)
61        {
62            buffer->valid(idx);
63            index = idx;
64        }
65
66        wire(TimeBuffer<T> *buf, int i)
67            : buffer(buf), index(i)
68        { }
69
70      public:
71        wire()
72        { }
73
74        wire(const wire &i)
75            : buffer(i.buffer), index(i.index)
76        { }
77
78        const wire &operator=(const wire &i)
79        {
80            buffer = i.buffer;
81            set(i.index);
82            return *this;
83        }
84
85        const wire &operator=(int idx)
86        {
87            set(idx);
88            return *this;
89        }
90
91        const wire &operator+=(int offset)
92        {
93            set(index + offset);
94            return *this;
95        }
96
97        const wire &operator-=(int offset)
98        {
99            set(index - offset);
100            return *this;
101        }
102
103        wire &operator++()
104        {
105            set(index + 1);
106            return *this;
107        }
108
109        wire &operator++(int)
110        {
111            int i = index;
112            set(index + 1);
113            return wire(this, i);
114        }
115
116        wire &operator--()
117        {
118            set(index - 1);
119            return *this;
120        }
121
122        wire &operator--(int)
123        {
124            int i = index;
125            set(index - 1);
126            return wire(this, i);
127        }
128        T &operator*() const { return *buffer->access(index); }
129        T *operator->() const { return buffer->access(index); }
130    };
131
132
133  public:
134    TimeBuffer(int p, int f)
135        : past(p), future(f), size(past + future + 1),
136          data(new char[size * sizeof(T)]), index(size), base(0)
137    {
138        assert(past >= 0 && future >= 0);
139        char *ptr = data;
140        for (int i = 0; i < size; i++) {
141            index[i] = ptr;
142            memset(ptr, 0, sizeof(T));
143            new (ptr) T;
144            ptr += sizeof(T);
145        }
146    }
147
148    TimeBuffer()
149        : data(NULL)
150    {
151    }
152
153    ~TimeBuffer()
154    {
155        for (int i = 0; i < size; ++i)
156            (reinterpret_cast<T *>(index[i]))->~T();
157        delete [] data;
158    }
159
160    void
161    advance()
162    {
163        if (++base >= size)
164            base = 0;
165
166        int ptr = base + future;
167        if (ptr >= size)
168            ptr -= size;
169        (reinterpret_cast<T *>(index[ptr]))->~T();
170        memset(index[ptr], 0, sizeof(T));
171        new (index[ptr]) T;
172    }
173
174    T *access(int idx)
175    {
176        //Need more complex math here to calculate index.
177        valid(idx);
178
179        int vector_index = idx + base;
180        if (vector_index >= size) {
181            vector_index -= size;
182        } else if (vector_index < 0) {
183            vector_index += size;
184        }
185
186        return reinterpret_cast<T *>(index[vector_index]);
187    }
188
189    T &operator[](int idx)
190    {
191        //Need more complex math here to calculate index.
192        valid(idx);
193
194        int vector_index = idx + base;
195        if (vector_index >= size) {
196            vector_index -= size;
197        } else if (vector_index < 0) {
198            vector_index += size;
199        }
200
201        return reinterpret_cast<T &>(*index[vector_index]);
202    }
203
204    wire getWire(int idx)
205    {
206        valid(idx);
207
208        return wire(this, idx);
209    }
210
211    wire zero()
212    {
213        return wire(this, 0);
214    }
215};
216
217#endif // __BASE_TIMEBUF_HH__
218
219