timebuf.hh revision 2873 
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 <vector>
36
37template <class T>
38class TimeBuffer
39{
40  protected:
41    int past;
42    int future;
43    int size;
44
45    char *data;
46    std::vector<char *> index;
47    int base;
48
49    void valid(int idx)
50    {
51        assert (idx >= -past && idx <= future);
52    }
53
54  public:
55    friend class wire;
56    class wire
57    {
58        friend class TimeBuffer;
59      protected:
60        TimeBuffer<T> *buffer;
61        int index;
62
63        void set(int idx)
64        {
65            buffer->valid(idx);
66            index = idx;
67        }
68
69        wire(TimeBuffer<T> *buf, int i)
70            : buffer(buf), index(i)
71        { }
72
73      public:
74        wire()
75        { }
76
77        wire(const wire &i)
78            : buffer(i.buffer), index(i.index)
79        { }
80
81        const wire &operator=(const wire &i)
82        {
83            buffer = i.buffer;
84            set(i.index);
85            return *this;
86        }
87
88        const wire &operator=(int idx)
89        {
90            set(idx);
91            return *this;
92        }
93
94        const wire &operator+=(int offset)
95        {
96            set(index + offset);
97            return *this;
98        }
99
100        const wire &operator-=(int offset)
101        {
102            set(index - offset);
103            return *this;
104        }
105
106        wire &operator++()
107        {
108            set(index + 1);
109            return *this;
110        }
111
112        wire &operator++(int)
113        {
114            int i = index;
115            set(index + 1);
116            return wire(this, i);
117        }
118
119        wire &operator--()
120        {
121            set(index - 1);
122            return *this;
123        }
124
125        wire &operator--(int)
126        {
127            int i = index;
128            set(index - 1);
129            return wire(this, i);
130        }
131        T &operator*() const { return *buffer->access(index); }
132        T *operator->() const { return buffer->access(index); }
133    };
134
135
136  public:
137    TimeBuffer(int p, int f)
138        : past(p), future(f), size(past + future + 1),
139          data(new char[size * sizeof(T)]), index(size), base(0)
140    {
141        assert(past >= 0 && future >= 0);
142        char *ptr = data;
143        for (int i = 0; i < size; i++) {
144            index[i] = ptr;
145            memset(ptr, 0, sizeof(T));
146            new (ptr) T;
147            ptr += sizeof(T);
148        }
149    }
150
151    TimeBuffer()
152        : data(NULL)
153    {
154    }
155
156    ~TimeBuffer()
157    {
158        for (int i = 0; i < size; ++i)
159            (reinterpret_cast<T *>(index[i]))->~T();
160        delete [] data;
161    }
162
163    void
164    advance()
165    {
166        if (++base >= size)
167            base = 0;
168
169        int ptr = base + future;
170        if (ptr >= size)
171            ptr -= size;
172        (reinterpret_cast<T *>(index[ptr]))->~T();
173        memset(index[ptr], 0, sizeof(T));
174        new (index[ptr]) T;
175    }
176
177    T *access(int idx)
178    {
179        //Need more complex math here to calculate index.
180        valid(idx);
181
182        int vector_index = idx + base;
183        if (vector_index >= size) {
184            vector_index -= size;
185        } else if (vector_index < 0) {
186            vector_index += size;
187        }
188
189        return reinterpret_cast<T *>(index[vector_index]);
190    }
191
192    T &operator[](int idx)
193    {
194        //Need more complex math here to calculate index.
195        valid(idx);
196
197        int vector_index = idx + base;
198        if (vector_index >= size) {
199            vector_index -= size;
200        } else if (vector_index < 0) {
201            vector_index += size;
202        }
203
204        return reinterpret_cast<T &>(*index[vector_index]);
205    }
206
207    wire getWire(int idx)
208    {
209        valid(idx);
210
211        return wire(this, idx);
212    }
213
214    wire zero()
215    {
216        return wire(this, 0);
217    }
218
219    int getSize()
220    {
221        return size;
222    }
223};
224
225#endif // __BASE_TIMEBUF_HH__
226
227