util/buffer.c

   1 /*
   2  * QEMU generic buffers
   3  *
   4  * Copyright (c) 2015 Red Hat, Inc.
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  */
  20
  21 #include "qemu/buffer.h"
  22
  23 #define BUFFER_MIN_INIT_SIZE 4096
  24
  25 void buffer_init(Buffer *buffer, const char *name, ...)
  26 {
  27     va_list ap;
  28
  29     va_start(ap, name);
  30     buffer->name = g_strdup_vprintf(name, ap);
  31     va_end(ap);
  32 }
  33
  34 void buffer_reserve(Buffer *buffer, size_t len)
  35 {
  36     if ((buffer->capacity - buffer->offset) < len) {
  37         buffer->capacity = pow2ceil(buffer->offset + len);
  38         buffer->capacity = MAX(buffer->capacity, BUFFER_MIN_INIT_SIZE);
  39         buffer->buffer = g_realloc(buffer->buffer, buffer->capacity);
  40     }
  41 }
  42
  43 gboolean buffer_empty(Buffer *buffer)
  44 {
  45     return buffer->offset == 0;
  46 }
  47
  48 uint8_t *buffer_end(Buffer *buffer)
  49 {
  50     return buffer->buffer + buffer->offset;
  51 }
  52
  53 void buffer_reset(Buffer *buffer)
  54 {
  55     buffer->offset = 0;
  56 }
  57
  58 void buffer_free(Buffer *buffer)
  59 {
  60     g_free(buffer->buffer);
  61     g_free(buffer->name);
  62     buffer->offset = 0;
  63     buffer->capacity = 0;
  64     buffer->buffer = NULL;
  65     buffer->name = NULL;
  66 }
  67
  68 void buffer_append(Buffer *buffer, const void *data, size_t len)
  69 {
  70     memcpy(buffer->buffer + buffer->offset, data, len);
  71     buffer->offset += len;
  72 }
  73
  74 void buffer_advance(Buffer *buffer, size_t len)
  75 {
  76     memmove(buffer->buffer, buffer->buffer + len,
  77             (buffer->offset - len));
  78     buffer->offset -= len;
  79 }