/* * 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 #include #include #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: *
    *
  • _start <= _stop *
  • _start < capacity *
  • _stop < 2 * capacity *
*/ template 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 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 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 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 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 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: *
    *
  • Writes are checked to ensure that overflows can't happen. *
  • Unserialization ensures that the data in the checkpoint fits * in the buffer. *
*/ template 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 void peek(OutputIterator out, size_t len) const { buf.peek(out, len); } template void read(OutputIterator out, size_t len) { buf.read(out, len); } template void write(InputIterator in, size_t len) { panic_if(size() + len > capacity(), "Trying to overfill FIFO buffer.\n"); buf.write(in, len); } private: CircleBuf buf; }; template void arrayParamOut(CheckpointOut &cp, const std::string &name, const CircleBuf ¶m) { std::vector temp(param.size()); param.peek(temp.begin(), temp.size()); arrayParamOut(cp, name, temp); } template void arrayParamIn(CheckpointIn &cp, const std::string &name, CircleBuf ¶m) { std::vector temp; arrayParamIn(cp, name, temp); param.flush(); param.write(temp.cbegin(), temp.size()); } template void arrayParamOut(CheckpointOut &cp, const std::string &name, const Fifo ¶m) { std::vector temp(param.size()); param.peek(temp.begin(), temp.size()); arrayParamOut(cp, name, temp); } template void arrayParamIn(CheckpointIn &cp, const std::string &name, Fifo ¶m) { std::vector 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__