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