src/base/circlebuf.hh

   1 /*
   2  * Copyright (c) 2015,2017-2018 ARM Limited
   3  * All rights reserved
   4  *
   5  * The license below extends only to copyright in the software and shall
   6  * not be construed as granting a license to any other intellectual
   7  * property including but not limited to intellectual property relating
   8  * to a hardware implementation of the functionality of the software
   9  * licensed hereunder.  You may use the software subject to the license
  10  * terms below provided that you ensure that this notice is replicated
  11  * unmodified and in its entirety in all distributions of the software,
  12  * modified or unmodified, in source code or in binary form.
  13  *
  14  * Redistribution and use in source and binary forms, with or without
  15  * modification, are permitted provided that the following conditions are
  16  * met: redistributions of source code must retain the above copyright
  17  * notice, this list of conditions and the following disclaimer;
  18  * redistributions in binary form must reproduce the above copyright
  19  * notice, this list of conditions and the following disclaimer in the
  20  * documentation and/or other materials provided with the distribution;
  21  * neither the name of the copyright holders nor the names of its
  22  * contributors may be used to endorse or promote products derived from
  23  * this software without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  26  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  27  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  28  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  29  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  30  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  31  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  35  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  *
  37  * Authors: Andreas Sandberg
  38  */
  39
  40 #ifndef __BASE_CIRCLEBUF_HH__
  41 #define __BASE_CIRCLEBUF_HH__
  42
  43 #include <algorithm>
  44 #include <cassert>
  45 #include <vector>
  46
  47 #include "base/circular_queue.hh"
  48 #include "base/logging.hh"
  49 #include "sim/serialize.hh"
  50
  51 /**
  52  * Circular buffer backed by a vector though a CircularQueue.
  53  *
  54  * The data in the cricular buffer is stored in a standard
  55  * vector.
  56  *
  57  */
  58 template<typename T>
  59 class CircleBuf : public CircularQueue<T>
  60 {
  61   public:
  62     explicit CircleBuf(size_t size)
  63         : CircularQueue<T>(size) {}
  64     using CircularQueue<T>::empty;
  65     using CircularQueue<T>::size;
  66     using CircularQueue<T>::capacity;
  67     using CircularQueue<T>::begin;
  68     using CircularQueue<T>::end;
  69     using CircularQueue<T>::pop_front;
  70     using CircularQueue<T>::advance_tail;
  71
  72     /**
  73      * Copy buffer contents without advancing the read pointer
  74      *
  75      * @param out Output iterator/pointer
  76      * @param len Number of elements to copy
  77      */
  78     template <class OutputIterator>
  79     void peek(OutputIterator out, size_t len) const {
  80         peek(out, 0, len);
  81     }
  82
  83     /**
  84      * Copy buffer contents without advancing the read pointer
  85      *
  86      * @param out Output iterator/pointer
  87      * @param offset Offset into the ring buffer
  88      * @param len Number of elements to copy
  89      */
  90     template <class OutputIterator>
  91     void peek(OutputIterator out, off_t offset, size_t len) const {
  92         panic_if(offset + len > size(),
  93                  "Trying to read past end of circular buffer.\n");
  94
  95         std::copy(begin() + offset, begin() + offset + len, out);
  96     }
  97
  98     /**
  99      * Copy buffer contents and advance the read pointer
 100      *
 101      * @param out Output iterator/pointer
 102      * @param len Number of elements to read
 103      */
 104     template <class OutputIterator>
 105     void read(OutputIterator out, size_t len) {
 106         peek(out, len);
 107         pop_front(len);
 108     }
 109
 110     /**
 111      * Add elements to the end of the ring buffers and advance.
 112      *
 113      * @param in Input iterator/pointer
 114      * @param len Number of elements to read
 115      */
 116     template <class InputIterator>
 117     void write(InputIterator in, size_t len) {
 118         // Writes that are larger than the backing store are allowed,
 119         // but only the last part of the buffer will be written.
 120         if (len > capacity()) {
 121             in += len - capacity();
 122             len = capacity();
 123         }
 124
 125         std::copy(in, in + len, end());
 126         advance_tail(len);
 127     }
 128 };
 129
 130 /**
 131  * Simple FIFO implementation backed by a circular buffer.
 132  *
 133  * This class provides the same basic functionallity as the circular
 134  * buffer with the folling differences:
 135  * <ul>
 136  *    <li>Writes are checked to ensure that overflows can't happen.
 137  *    <li>Unserialization ensures that the data in the checkpoint fits
 138  *        in the buffer.
 139  * </ul>
 140  */
 141 template<typename T>
 142 class Fifo
 143 {
 144   public:
 145     typedef T value_type;
 146
 147   public:
 148     Fifo(size_t size)
 149         : buf(size) {}
 150
 151     bool empty() const { return buf.empty(); }
 152     size_t size() const { return buf.size(); }
 153     size_t capacity() const { return buf.capacity(); }
 154
 155     void flush() { buf.flush(); }
 156
 157     template <class OutputIterator>
 158     void peek(OutputIterator out, size_t len) const { buf.peek(out, len); }
 159     template <class OutputIterator>
 160     void read(OutputIterator out, size_t len) { buf.read(out, len); }
 161
 162     template <class InputIterator>
 163     void write(InputIterator in, size_t len) {
 164         panic_if(size() + len > capacity(),
 165                  "Trying to overfill FIFO buffer.\n");
 166         buf.write(in, len);
 167     }
 168
 169   private:
 170     CircleBuf<value_type> buf;
 171 };
 172
 173
 174 template <typename T>
 175 void
 176 arrayParamOut(CheckpointOut &cp, const std::string &name,
 177               const CircleBuf<T> &param)
 178 {
 179     std::vector<T> temp(param.size());
 180     param.peek(temp.begin(), temp.size());
 181     arrayParamOut(cp, name, temp);
 182 }
 183
 184 template <typename T>
 185 void
 186 arrayParamIn(CheckpointIn &cp, const std::string &name,
 187              CircleBuf<T> &param)
 188 {
 189     std::vector<T> temp;
 190     arrayParamIn(cp, name, temp);
 191
 192     param.flush();
 193     param.write(temp.cbegin(), temp.size());
 194 }
 195
 196 template <typename T>
 197 void
 198 arrayParamOut(CheckpointOut &cp, const std::string &name,
 199               const Fifo<T> &param)
 200 {
 201     std::vector<T> temp(param.size());
 202     param.peek(temp.begin(), temp.size());
 203     arrayParamOut(cp, name, temp);
 204 }
 205
 206 template <typename T>
 207 void
 208 arrayParamIn(CheckpointIn &cp, const std::string &name,
 209              Fifo<T> &param)
 210 {
 211     std::vector<T> temp;
 212     arrayParamIn(cp, name, temp);
 213
 214     fatal_if(param.capacity() < temp.size(),
 215              "Trying to unserialize data into too small FIFO\n");
 216
 217     param.flush();
 218     param.write(temp.cbegin(), temp.size());
 219 }
 220
 221 #endif // __BASE_CIRCLEBUF_HH__