rockbox/apps/plugins/lib/overlay.c
Thomas Martitz 0d4585b28f Extend lc_open() to also being able to load overlay plugins.
For this it needs to look at the plugin header. Since lc_open() doesn't know
it's a plugin, the header needs to be changed slightly to include the new lc_header (which needs to be the first element in plugin_header so it can be casted savely).

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@28054 a1c6a512-1295-4272-9138-f99709370657
2010-09-09 16:17:21 +00:00

102 lines
3 KiB
C

/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Overlay loader
*
* Copyright (C) 2006 Jens Arnold
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "plugin.h"
#include "overlay.h"
/* load and run a plugin linked as an overlay.
arguments:
parameter = plugin parameter, passed on to the overlay
filename = overlay file name, absolute path as usual
name = overlay display name
result:
return value from the overlay
As long as a large plugin to be overlayed doesn't use the audiobuffer
itself, no adjustments in the plugin source code are necessary to make
it work as an overlay, it only needs an adapted linker script.
If the overlayed plugin *does* use the audiobuffer itself, it needs
to make sure not to overwrite itself.
The linker script for the overlay should use a base address towards the
end of the audiobuffer, just low enough to make the overlay fit. */
enum plugin_status run_overlay(const void* parameter,
unsigned char *filename, unsigned char *name)
{
size_t audiobuf_size;
unsigned char *audiobuf;
void *handle;
struct plugin_header *p_hdr;
struct lc_header *hdr;
audiobuf = rb->plugin_get_audio_buffer(&audiobuf_size);
if (!audiobuf)
{
rb->splash(2*HZ, "Can't optain memory");
goto error;
}
handle = rb->lc_open(filename, audiobuf, audiobuf_size);
if (!handle)
{
rb->splashf(2*HZ, "Can't open %s", filename);
goto error;
}
p_hdr = rb->lc_get_header(handle);
if (!p_hdr)
{
rb->splash(2*HZ, "Can't get header");
goto error_close;
}
else
hdr = &p_hdr->lc_hdr;
if (hdr->magic != PLUGIN_MAGIC || hdr->target_id != TARGET_ID)
{
rb->splashf(2*HZ, "%s overlay: Incompatible model.", name);
goto error_close;
}
if (hdr->api_version > PLUGIN_API_VERSION
|| hdr->api_version < PLUGIN_MIN_API_VERSION)
{
rb->splashf(2*HZ, "%s overlay: Incompatible version.", name);
goto error_close;
}
rb->lc_close(handle);
*(p_hdr->api) = rb;
return p_hdr->entry_point(parameter);
error_close:
rb->lc_close(handle);
error:
return PLUGIN_ERROR;
}