src/base/circlebuf.cc

   1 /*
   2  * Copyright (c) 2002-2005 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  */
  30
  31 #include <algorithm>
  32 #include <cstdio>
  33 #include <cstring>
  34 #include <string>
  35
  36 #include "base/atomicio.hh"
  37 #include "base/circlebuf.hh"
  38 #include "base/cprintf.hh"
  39 #include "base/intmath.hh"
  40
  41 using namespace std;
  42
  43 CircleBuf::CircleBuf(int l)
  44     : _rollover(false), _buflen(l), _size(0), _start(0), _stop(0)
  45 {
  46     _buf = new char[_buflen];
  47 }
  48
  49 CircleBuf::~CircleBuf()
  50 {
  51     if (_buf)
  52         delete [] _buf;
  53 }
  54
  55 void
  56 CircleBuf::dump()
  57 {
  58     cprintf("start = %10d, stop = %10d, buflen = %10d\n",
  59             _start, _stop, _buflen);
  60     fflush(stdout);
  61     atomic_write(STDOUT_FILENO, _buf, _buflen);
  62     atomic_write(STDOUT_FILENO, "<\n", 2);
  63 }
  64
  65 void
  66 CircleBuf::flush()
  67 {
  68     _start = 0;
  69     _stop = 0;
  70     _rollover = false;
  71 }
  72
  73 void
  74 CircleBuf::read(char *b, int len)
  75 {
  76     _size -= len;
  77     if (_size < 0)
  78         _size = 0;
  79
  80     if (_stop > _start) {
  81         len = min(len, _stop - _start);
  82         memcpy(b, _buf + _start, len);
  83         _start += len;
  84     }
  85     else {
  86         int endlen = _buflen - _start;
  87         if (endlen > len) {
  88             memcpy(b, _buf + _start, len);
  89             _start += len;
  90         }
  91         else {
  92             memcpy(b, _buf + _start, endlen);
  93             _start = min(len - endlen, _stop);
  94             memcpy(b + endlen, _buf, _start);
  95         }
  96     }
  97 }
  98
  99 void
 100 CircleBuf::read(int fd, int len)
 101 {
 102     _size -= len;
 103     if (_size < 0)
 104         _size = 0;
 105
 106     if (_stop > _start) {
 107         len = min(len, _stop - _start);
 108         atomic_write(fd, _buf + _start, len);
 109         _start += len;
 110     }
 111     else {
 112         int endlen = _buflen - _start;
 113         if (endlen > len) {
 114             atomic_write(fd, _buf + _start, len);
 115             _start += len;
 116         }
 117         else {
 118             atomic_write(fd, _buf + _start, endlen);
 119             _start = min(len - endlen, _stop);
 120             atomic_write(fd, _buf, _start);
 121         }
 122     }
 123 }
 124
 125 void
 126 CircleBuf::read(int fd)
 127 {
 128     _size = 0;
 129
 130     if (_stop > _start) {
 131         atomic_write(fd, _buf + _start, _stop - _start);
 132     }
 133     else {
 134         atomic_write(fd, _buf + _start, _buflen - _start);
 135         atomic_write(fd, _buf, _stop);
 136     }
 137
 138     _start = _stop;
 139 }
 140
 141 void
 142 CircleBuf::read(ostream &out)
 143 {
 144     _size = 0;
 145
 146     if (_stop > _start) {
 147         out.write(_buf + _start, _stop - _start);
 148     }
 149     else {
 150         out.write(_buf + _start, _buflen - _start);
 151         out.write(_buf, _stop);
 152     }
 153
 154     _start = _stop;
 155 }
 156
 157 void
 158 CircleBuf::readall(int fd)
 159 {
 160     if (_rollover)
 161         atomic_write(fd, _buf + _stop, _buflen - _stop);
 162
 163     atomic_write(fd, _buf, _stop);
 164     _start = _stop;
 165 }
 166
 167 void
 168 CircleBuf::write(char b)
 169 {
 170     write(&b, 1);
 171 }
 172
 173 void
 174 CircleBuf::write(const char *b)
 175 {
 176     write(b, strlen(b));
 177 }
 178
 179 void
 180 CircleBuf::write(const char *b, int len)
 181 {
 182     if (len <= 0)
 183         return;
 184
 185     _size += len;
 186     if (_size > _buflen)
 187         _size = _buflen;
 188
 189     int old_start = _start;
 190     int old_stop = _stop;
 191
 192     if (len >= _buflen) {
 193         _start = 0;
 194         _stop = _buflen;
 195         _rollover = true;
 196         memcpy(_buf, b + (len - _buflen), _buflen);
 197         return;
 198     }
 199
 200     if (_stop + len <= _buflen) {
 201         memcpy(_buf + _stop, b, len);
 202         _stop += len;
 203     } else {
 204         int end_len = _buflen - old_stop;
 205         _stop = len - end_len;
 206         memcpy(_buf + old_stop, b, end_len);
 207         memcpy(_buf, b + end_len, _stop);
 208         _rollover = true;
 209     }
 210
 211     if ((old_start > old_stop && old_start < _stop) ||
 212         (old_start < old_stop && _stop < old_stop))
 213         _start = _stop + 1;
 214 }