apps/plugins/lib/overlay.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Overlay loader
  11  *
  12  * Copyright (C) 2006 Jens Arnold
  13  *
  14  * All files in this archive are subject to the GNU General Public License.
  15  * See the file COPYING in the source tree root for full license agreement.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21
  22 #ifndef SIMULATOR
  23 #include "plugin.h"
  24
  25 /* load and run a plugin linked as an overlay.
  26
  27  arguments:
  28    rb        = pointer to plugin api, also passed on to the overlay
  29    parameter = plugin parameter, passed on to the overlay
  30    filename  = overlay file name, absolute path as usual
  31    name      = overlay display name
  32
  33  result:
  34    return value from the overlay
  35
  36    As long as a large plugin to be overlayed doesn't use the audiobuffer
  37    itself, no adjustments in the plugin source code are necessary to make
  38    it work as an overlay, it only needs an adapted linker script.
  39
  40    If the overlayed plugin *does* use the audiobuffer itself, it needs
  41    to make sure not to overwrite itself.
  42
  43    The linker script for the overlay should use a base address towards the
  44    end of the audiobuffer, just low enough to make the overlay fit. */
  45
  46 enum plugin_status run_overlay(struct plugin_api* rb, void* parameter,
  47                                unsigned char *filename, unsigned char *name)
  48 {
  49     int fd, readsize;
  50     ssize_t audiobuf_size;
  51     unsigned char *audiobuf;
  52     static struct plugin_header header;
  53
  54     fd = rb->open(filename, O_RDONLY);
  55     if (fd < 0)
  56     {
  57         rb->splash(2*HZ, "Can't open %s", filename);
  58         return PLUGIN_ERROR;
  59     }
  60     readsize = rb->read(fd, &header, sizeof(header));
  61     rb->close(fd);
  62     /* Close for now. Less code than doing it in all error checks.
  63      * Would need to seek back anyway. */
  64
  65     if (readsize != sizeof(header))
  66     {
  67         rb->splash(2*HZ, "Reading %s overlay failed.", name);
  68         return PLUGIN_ERROR;
  69     }
  70     if (header.magic != PLUGIN_MAGIC || header.target_id != TARGET_ID)
  71     {
  72         rb->splash(2*HZ, "%s overlay: Incompatible model.", name);
  73         return PLUGIN_ERROR;
  74     }
  75     if (header.api_version != PLUGIN_API_VERSION)
  76     {
  77         rb->splash(2*HZ, "%s overlay: Incompatible version.", name);
  78         return PLUGIN_ERROR;
  79     }
  80
  81     audiobuf = rb->plugin_get_audio_buffer((size_t *)&audiobuf_size);
  82     if (header.load_addr < audiobuf ||
  83         header.end_addr > audiobuf + audiobuf_size)
  84     {
  85         rb->splash(2*HZ, "%s overlay doesn't fit into memory.", name);
  86         return PLUGIN_ERROR;
  87     }
  88
  89     fd = rb->open(filename, O_RDONLY);
  90     if (fd < 0)
  91     {
  92         rb->splash(2*HZ, "Can't open %s", filename);
  93         return PLUGIN_ERROR;
  94     }
  95     readsize = rb->read(fd, header.load_addr, header.end_addr - header.load_addr);
  96     rb->close(fd);
  97
  98     if (readsize < 0)
  99     {
 100         rb->splash(2*HZ, "Reading %s overlay failed.", name);
 101         return PLUGIN_ERROR;
 102     }
 103     /* Zero out bss area */
 104     rb->memset(header.load_addr + readsize, 0,
 105                header.end_addr - (header.load_addr + readsize));
 106
 107     return header.entry_point(rb, parameter);
 108 }
 109 #endif