lib/skin_parser/skin_buffer.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id: skin_buffer.c 25962 2010-05-12 09:31:40Z jdgordon $
   9  *
  10  * Copyright (C) 2002 by Linus Nielsen Feltzing
  11  * Copyright (C) 2009 Jonathan Gordon
  12  *
  13  * This program is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU General Public License
  15  * as published by the Free Software Foundation; either version 2
  16  * of the License, or (at your option) any later version.
  17  *
  18  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  19  * KIND, either express or implied.
  20  *
  21  ****************************************************************************/
  22
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include <stdlib.h>
  26
  27 #include "skin_buffer.h"
  28
  29 #ifdef ROCKBOX
  30 static size_t buf_size;
  31 static unsigned char *buffer_start = NULL;
  32 static unsigned char *buffer_front = NULL;
  33 #endif
  34
  35 void skin_buffer_init(char* buffer, size_t size)
  36 {
  37 #if defined(ROCKBOX)
  38     buffer_start = buffer_front = buffer;
  39     buf_size = size;
  40 #endif
  41 }
  42
  43 /* Allocate size bytes from the buffer */
  44 void* skin_buffer_alloc(size_t size)
  45 {
  46     void *retval = NULL;
  47 #ifdef ROCKBOX
  48     if (size > skin_buffer_freespace())
  49         return NULL;
  50     retval = buffer_front;
  51     buffer_front += size;
  52     /* 32-bit aligned */
  53     buffer_front = (void *)(((unsigned long)buffer_front + 3) & ~3);
  54 #else
  55     retval = malloc(size);
  56 #endif
  57     return retval;
  58 }
  59
  60
  61 #ifdef ROCKBOX
  62 /* get the number of bytes currently being used */
  63 size_t skin_buffer_usage(void)
  64 {
  65     return buffer_front - buffer_start;
  66 }
  67 size_t skin_buffer_freespace(void)
  68 {
  69     return buf_size - skin_buffer_usage();
  70 }
  71
  72 static unsigned char *saved_buffer_pos = NULL;
  73 void skin_buffer_save_position(void)
  74 {
  75     saved_buffer_pos = buffer_front;
  76 }
  77
  78 void skin_buffer_restore_position(void)
  79 {
  80     if (saved_buffer_pos)
  81         buffer_front = saved_buffer_pos;
  82 }
  83 #endif