rockbox/lib/rbcodec/codecs/codec_crt0.c

/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2006 Tomasz Malesinski
 *
 * 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 "config.h"
#include "codecs.h"

struct codec_api *ci DATA_ATTR;

extern unsigned char plugin_bss_start[];
extern unsigned char plugin_end_addr[];

/* stub, the entry point is called via its reference in __header to
 * avoid warning with certain compilers */
int _start(void) {return 0;}

enum codec_status codec_start(enum codec_entry_call_reason reason)
{
#if (CONFIG_PLATFORM & PLATFORM_NATIVE)
    if (reason == CODEC_LOAD)
    {
#ifdef USE_IRAM
        extern char iramcopy[], iramstart[], iramend[], iedata[], iend[];
        size_t iram_size = iramend - iramstart;
        size_t ibss_size = iend - iedata;
        if (iram_size > 0 || ibss_size > 0)
        {
            ci->memcpy(iramstart, iramcopy, iram_size);
            ci->memset(iedata, 0, ibss_size);
            /* make the icache (if it exists) up to date with the new code */
            ci->commit_discard_idcache();
            /* barrier to prevent reordering iram copy and BSS clearing,
             * because the BSS segment alias the IRAM copy.
             */
            asm volatile ("" ::: "memory");
        }
#endif /* PLUGIN_USE_IRAM */
        ci->memset(plugin_bss_start, 0, plugin_end_addr - plugin_bss_start);
        /* Some parts of bss may be used via a no-cache alias (at least
         * portalplayer has this). If we don't clear the cache, those aliases
         * may read garbage */
        ci->commit_dcache();
    }
#endif /* CONFIG_PLATFORM */

    /* Note: If for any reason codec_main would not be called with CODEC_LOAD
     * because the above code failed then it must not be ever be called with
     * any other value and some strategy to avoid doing so must be conceived */
    return codec_main(reason);
}

#if defined(CPU_ARM) && (CONFIG_PLATFORM & PLATFORM_NATIVE)
void __attribute__((naked)) __div0(void)
{
    asm volatile("bx %0" : : "r"(ci->__div0));
}
#endif