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/*
* Copyright (c) 2015 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
* not be construed as granting a license to any other intellectual
* property including but not limited to intellectual property relating
* to a hardware implementation of the functionality of the software
* licensed hereunder. You may use the software subject to the license
* terms below provided that you ensure that this notice is replicated
* unmodified and in its entirety in all distributions of the software,
* modified or unmodified, in source code or in binary form.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Authors: Andreas Sandberg
*/
#ifndef __BASE_CIRCLEBUF_HH__
#define __BASE_CIRCLEBUF_HH__
#include <algorithm>
#include <cassert>
#include <vector>
#include "base/misc.hh"
#include "sim/serialize.hh"
/**
* Circular buffer backed by a vector
*
* The data in the cricular buffer is stored in a standard
* vector. _start designates the first element in the buffer and _stop
* points to the last element + 1 (i.e., the position of the next
* insertion). The _stop index may be outside the range of the backing
* store, which means that the actual index must be calculated as
* _stop % capacity.
*
* Invariants:
* <ul>
* <li>_start <= _stop
* <li>_start < capacity
* <li>_stop < 2 * capacity
* </ul>
*/
template<typename T>
class CircleBuf
{
public:
typedef T value_type;
public:
explicit CircleBuf(size_t size)
: buf(size), _start(0), _stop(0) {}
/** Is the buffer empty? */
bool empty() const { return _stop == _start; }
/**
* Return the maximum number of elements that can be stored in
* the buffer at any one time.
*/
size_t capacity() const { return buf.size(); }
/** Return the number of elements stored in the buffer. */
size_t size() const { return _stop - _start; }
/**
* Remove all the elements in the buffer.
*
* Note: This does not actually remove elements from the backing
* store.
*/
void flush() {
_start = 0;
_stop = 0;
}
/**
* Copy buffer contents without advancing the read pointer
*
* @param out Output iterator/pointer
* @param len Number of elements to copy
*/
template <class OutputIterator>
void peek(OutputIterator out, size_t len) const {
peek(out, 0, len);
}
/**
* Copy buffer contents without advancing the read pointer
*
* @param out Output iterator/pointer
* @param offset Offset into the ring buffer
* @param len Number of elements to copy
*/
template <class OutputIterator>
void peek(OutputIterator out, off_t offset, size_t len) const {
panic_if(offset + len > size(),
"Trying to read past end of circular buffer.\n");
const off_t real_start((offset + _start) % buf.size());
if (real_start + len <= buf.size()) {
std::copy(buf.begin() + real_start,
buf.begin() + real_start + len,
out);
} else {
const size_t head_size(buf.size() - real_start);
const size_t tail_size(len - head_size);
std::copy(buf.begin() + real_start, buf.end(),
out);
std::copy(buf.begin(), buf.begin() + tail_size,
out + head_size);
}
}
/**
* Copy buffer contents and advance the read pointer
*
* @param out Output iterator/pointer
* @param len Number of elements to read
*/
template <class OutputIterator>
void read(OutputIterator out, size_t len) {
peek(out, len);
_start += len;
normalize();
}
/**
* Add elements to the end of the ring buffers and advance.
*
* @param in Input iterator/pointer
* @param len Number of elements to read
*/
template <class InputIterator>
void write(InputIterator in, size_t len) {
// Writes that are larger than the backing store are allowed,
// but only the last part of the buffer will be written.
if (len > buf.size()) {
in += len - buf.size();
len = buf.size();
}
const size_t next(_stop % buf.size());
const size_t head_len(std::min(buf.size() - next, len));
std::copy(in, in + head_len, buf.begin() + next);
std::copy(in + head_len, in + len, buf.begin());
_stop += len;
// We may have written past the old _start pointer. Readjust
// the _start pointer to remove the oldest entries in that
// case.
if (size() > buf.size())
_start = _stop - buf.size();
normalize();
}
protected:
/**
* Normalize the start and stop pointers to ensure that pointer
* invariants hold after updates.
*/
void normalize() {
if (_start >= buf.size()) {
_stop -= buf.size();
_start -= buf.size();
}
assert(_start < buf.size());
assert(_stop < 2 * buf.size());
assert(_start <= _stop);
}
protected:
std::vector<value_type> buf;
size_t _start;
size_t _stop;
};
/**
* Simple FIFO implementation backed by a circular buffer.
*
* This class provides the same basic functionallity as the circular
* buffer with the folling differences:
* <ul>
* <li>Writes are checked to ensure that overflows can't happen.
* <li>Unserialization ensures that the data in the checkpoint fits
* in the buffer.
* </ul>
*/
template<typename T>
class Fifo
{
public:
typedef T value_type;
public:
Fifo(size_t size)
: buf(size) {}
bool empty() const { return buf.empty(); }
size_t size() const { return buf.size(); }
size_t capacity() const { return buf.capacity(); }
void flush() { buf.flush(); }
template <class OutputIterator>
void peek(OutputIterator out, size_t len) const { buf.peek(out, len); }
template <class OutputIterator>
void read(OutputIterator out, size_t len) { buf.read(out, len); }
template <class InputIterator>
void write(InputIterator in, size_t len) {
panic_if(size() + len > capacity(),
"Trying to overfill FIFO buffer.\n");
buf.write(in, len);
}
private:
CircleBuf<value_type> buf;
};
template <typename T>
static void
arrayParamOut(CheckpointOut &cp, const std::string &name,
const CircleBuf<T> &param)
{
std::vector<T> temp(param.size());
param.peek(temp.begin(), temp.size());
arrayParamOut(cp, name, temp);
}
template <typename T>
static void
arrayParamIn(CheckpointIn &cp, const std::string &name,
CircleBuf<T> &param)
{
std::vector<T> temp;
arrayParamIn(cp, name, temp);
param.flush();
param.write(temp.cbegin(), temp.size());
}
template <typename T>
static void
arrayParamOut(CheckpointOut &cp, const std::string &name,
const Fifo<T> &param)
{
std::vector<T> temp(param.size());
param.peek(temp.begin(), temp.size());
arrayParamOut(cp, name, temp);
}
template <typename T>
static void
arrayParamIn(CheckpointIn &cp, const std::string &name,
Fifo<T> &param)
{
std::vector<T> temp;
arrayParamIn(cp, name, temp);
fatal_if(param.capacity() < temp.size(),
"Trying to unserialize data into too small FIFO\n");
param.flush();
param.write(temp.cbegin(), temp.size());
}
#endif // __BASE_CIRCLEBUF_HH__