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 #ifndef SIMULATOR
  25 #include "plugin.h"
  26 #include "overlay.h"
  27
  28 /* load and run a plugin linked as an overlay.
  29
  30  arguments:
  31    rb        = pointer to plugin api, also passed on to the overlay
  32    parameter = plugin parameter, passed on to the overlay
  33    filename  = overlay file name, absolute path as usual
  34    name      = overlay display name
  35
  36  result:
  37    return value from the overlay
  38
  39    As long as a large plugin to be overlayed doesn't use the audiobuffer
  40    itself, no adjustments in the plugin source code are necessary to make
  41    it work as an overlay, it only needs an adapted linker script.
  42
  43    If the overlayed plugin *does* use the audiobuffer itself, it needs
  44    to make sure not to overwrite itself.
  45
  46    The linker script for the overlay should use a base address towards the
  47    end of the audiobuffer, just low enough to make the overlay fit. */
  48
  49 enum plugin_status run_overlay(const void* parameter,
  50                                unsigned char *filename, unsigned char *name)
  51 {
  52     int fd, readsize;
  53     ssize_t audiobuf_size;
  54     unsigned char *audiobuf;
  55     static struct plugin_header header;
  56
  57     fd = rb->open(filename, O_RDONLY);
  58     if (fd < 0)
  59     {
  60         rb->splashf(2*HZ, "Can't open %s", filename);
  61         return PLUGIN_ERROR;
  62     }
  63     readsize = rb->read(fd, &header, sizeof(header));
  64     rb->close(fd);
  65     /* Close for now. Less code than doing it in all error checks.
  66      * Would need to seek back anyway. */
  67
  68     if (readsize != sizeof(header))
  69     {
  70         rb->splashf(2*HZ, "Reading %s overlay failed.", name);
  71         return PLUGIN_ERROR;
  72     }
  73     if (header.magic != PLUGIN_MAGIC || header.target_id != TARGET_ID)
  74     {
  75         rb->splashf(2*HZ, "%s overlay: Incompatible model.", name);
  76         return PLUGIN_ERROR;
  77     }
  78     if (header.api_version != PLUGIN_API_VERSION)
  79     {
  80         rb->splashf(2*HZ, "%s overlay: Incompatible version.", name);
  81         return PLUGIN_ERROR;
  82     }
  83
  84     audiobuf = rb->plugin_get_audio_buffer((size_t *)&audiobuf_size);
  85     if (header.load_addr < audiobuf ||
  86         header.end_addr > audiobuf + audiobuf_size)
  87     {
  88         rb->splashf(2*HZ, "%s overlay doesn't fit into memory.", name);
  89         return PLUGIN_ERROR;
  90     }
  91
  92     fd = rb->open(filename, O_RDONLY);
  93     if (fd < 0)
  94     {
  95         rb->splashf(2*HZ, "Can't open %s", filename);
  96         return PLUGIN_ERROR;
  97     }
  98     readsize = rb->read(fd, header.load_addr, header.end_addr - header.load_addr);
  99     rb->close(fd);
 100
 101     if (readsize < 0)
 102     {
 103         rb->splashf(2*HZ, "Reading %s overlay failed.", name);
 104         return PLUGIN_ERROR;
 105     }
 106     /* Zero out bss area */
 107     rb->memset(header.load_addr + readsize, 0,
 108                header.end_addr - (header.load_addr + readsize));
 109
 110     *(header.api) = rb;
 111     return header.entry_point(parameter);
 112 }
 113 #endif