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  * This program is free software; you can redistribute it and/or
  15  * modify it under the terms of the GNU General Public License
  16  * as published by the Free Software Foundation; either version 2
  17  * of the License, or (at your option) any later version.
  18  *
  19  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  20  * KIND, either express or implied.
  21  *
  22  ****************************************************************************/
  23
  24 #include "plugin.h"
  25 #include "overlay.h"
  26
  27 /* load and run a plugin linked as an overlay.
  28
  29  arguments:
  30    parameter = plugin parameter, passed on to the overlay
  31    filename  = overlay file name, absolute path as usual
  32    name      = overlay display name
  33
  34  result:
  35    return value from the overlay
  36
  37    As long as a large plugin to be overlayed doesn't use the audiobuffer
  38    itself, no adjustments in the plugin source code are necessary to make
  39    it work as an overlay, it only needs an adapted linker script.
  40
  41    If the overlayed plugin *does* use the audiobuffer itself, it needs
  42    to make sure not to overwrite itself.
  43
  44    The linker script for the overlay should use a base address towards the
  45    end of the audiobuffer, just low enough to make the overlay fit. */
  46
  47 enum plugin_status run_overlay(const void* parameter,
  48                                unsigned char *filename, unsigned char *name)
  49 {
  50     size_t audiobuf_size;
  51     unsigned char *audiobuf;
  52     void *handle;
  53     struct plugin_header *p_hdr;
  54     struct lc_header     *hdr;
  55
  56     audiobuf = rb->plugin_get_audio_buffer(&audiobuf_size);
  57     if (!audiobuf)
  58     {
  59         rb->splash(2*HZ, "Can't optain memory");
  60         goto error;
  61     }
  62
  63     handle = rb->lc_open(filename, audiobuf, audiobuf_size);
  64     if (!handle)
  65     {
  66         rb->splashf(2*HZ, "Can't open %s", filename);
  67         goto error;
  68     }
  69
  70     p_hdr = rb->lc_get_header(handle);
  71     if (!p_hdr)
  72     {
  73         rb->splash(2*HZ, "Can't get header");
  74         goto error_close;
  75     }
  76     else
  77         hdr = &p_hdr->lc_hdr;
  78
  79     if (hdr->magic != PLUGIN_MAGIC || hdr->target_id != TARGET_ID)
  80     {
  81         rb->splashf(2*HZ, "%s overlay: Incompatible model.", name);
  82         goto error_close;
  83     }
  84
  85
  86     if (hdr->api_version > PLUGIN_API_VERSION
  87         || hdr->api_version < PLUGIN_MIN_API_VERSION)
  88     {
  89         rb->splashf(2*HZ, "%s overlay: Incompatible version.", name);
  90         goto error_close;
  91     }
  92
  93     rb->lc_close(handle);
  94
  95     *(p_hdr->api) = rb;
  96     return p_hdr->entry_point(parameter);
  97
  98 error_close:
  99     rb->lc_close(handle);
 100 error:
 101     return PLUGIN_ERROR;
 102 }