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 <string>
  33
  34 #include <stdio.h>
  35 #include <string.h>
  36 #include <unistd.h>
  37
  38 #include "base/circlebuf.hh"
  39 #include "base/cprintf.hh"
  40 #include "base/intmath.hh"
  41
  42 using namespace std;
  43
  44 CircleBuf::CircleBuf(int l)
  45     : _rollover(false), _buflen(l), _size(0), _start(0), _stop(0)
  46 {
  47     _buf = new char[_buflen];
  48 }
  49
  50 CircleBuf::~CircleBuf()
  51 {
  52     if (_buf)
  53         delete [] _buf;
  54 }
  55
  56 void
  57 CircleBuf::dump()
  58 {
  59     cprintf("start = %10d, stop = %10d, buflen = %10d\n",
  60             _start, _stop, _buflen);
  61     fflush(stdout);
  62     ::write(STDOUT_FILENO, _buf, _buflen);
  63     ::write(STDOUT_FILENO, "<\n", 2);
  64 }
  65
  66 void
  67 CircleBuf::flush()
  68 {
  69     _start = 0;
  70     _stop = 0;
  71     _rollover = false;
  72 }
  73
  74 void
  75 CircleBuf::read(char *b, int len)
  76 {
  77     _size -= len;
  78     if (_size < 0)
  79         _size = 0;
  80
  81     if (_stop > _start) {
  82         len = min(len, _stop - _start);
  83         memcpy(b, _buf + _start, len);
  84         _start += len;
  85     }
  86     else {
  87         int endlen = _buflen - _start;
  88         if (endlen > len) {
  89             memcpy(b, _buf + _start, len);
  90             _start += len;
  91         }
  92         else {
  93             memcpy(b, _buf + _start, endlen);
  94             _start = min(len - endlen, _stop);
  95             memcpy(b + endlen, _buf, _start);
  96         }
  97     }
  98 }
  99
 100 void
 101 CircleBuf::read(int fd, int len)
 102 {
 103     _size -= len;
 104     if (_size < 0)
 105         _size = 0;
 106
 107     if (_stop > _start) {
 108         len = min(len, _stop - _start);
 109         ::write(fd, _buf + _start, len);
 110         _start += len;
 111     }
 112     else {
 113         int endlen = _buflen - _start;
 114         if (endlen > len) {
 115             ::write(fd, _buf + _start, len);
 116             _start += len;
 117         }
 118         else {
 119             ::write(fd, _buf + _start, endlen);
 120             _start = min(len - endlen, _stop);
 121             ::write(fd, _buf, _start);
 122         }
 123     }
 124 }
 125
 126 void
 127 CircleBuf::read(int fd)
 128 {
 129     _size = 0;
 130
 131     if (_stop > _start) {
 132         ::write(fd, _buf + _start, _stop - _start);
 133     }
 134     else {
 135         ::write(fd, _buf + _start, _buflen - _start);
 136         ::write(fd, _buf, _stop);
 137     }
 138
 139     _start = _stop;
 140 }
 141
 142 void
 143 CircleBuf::read(ostream &out)
 144 {
 145     _size = 0;
 146
 147     if (_stop > _start) {
 148         out.write(_buf + _start, _stop - _start);
 149     }
 150     else {
 151         out.write(_buf + _start, _buflen - _start);
 152         out.write(_buf, _stop);
 153     }
 154
 155     _start = _stop;
 156 }
 157
 158 void
 159 CircleBuf::readall(int fd)
 160 {
 161     if (_rollover)
 162         ::write(fd, _buf + _stop, _buflen - _stop);
 163
 164     ::write(fd, _buf, _stop);
 165     _start = _stop;
 166 }
 167
 168 void
 169 CircleBuf::write(char b)
 170 {
 171     write(&b, 1);
 172 }
 173
 174 void
 175 CircleBuf::write(const char *b)
 176 {
 177     write(b, strlen(b));
 178 }
 179
 180 void
 181 CircleBuf::write(const char *b, int len)
 182 {
 183     if (len <= 0)
 184         return;
 185
 186     _size += len;
 187     if (_size > _buflen)
 188         _size = _buflen;
 189
 190     int old_start = _start;
 191     int old_stop = _stop;
 192
 193     if (len >= _buflen) {
 194         _start = 0;
 195         _stop = _buflen;
 196         _rollover = true;
 197         memcpy(_buf, b + (len - _buflen), _buflen);
 198         return;
 199     }
 200
 201     if (_stop + len <= _buflen) {
 202         memcpy(_buf + _stop, b, len);
 203         _stop += len;
 204     } else {
 205         int end_len = _buflen - old_stop;
 206         _stop = len - end_len;
 207         memcpy(_buf + old_stop, b, end_len);
 208         memcpy(_buf, b + end_len, _stop);
 209         _rollover = true;
 210     }
 211
 212     if (old_start > old_stop && old_start < _stop ||
 213         old_start < old_stop && _stop < old_stop)
 214         _start = _stop + 1;
 215 }