src/bsp/lk/arch/arm/arm-m/start.c

/*
 * Copyright (c) 2012 Travis Geiselbrecht
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files
 * (the "Software"), to deal in the Software without restriction,
 * including without limitation the rights to use, copy, modify, merge,
 * publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
#include <debug.h>
#include <compiler.h>
#include <stdint.h>

/* externals */
extern unsigned int __data_start_rom, __data_start, __data_end;
extern unsigned int __bss_start, __bss_end;

extern void lk_main(void) __NO_RETURN __EXTERNALLY_VISIBLE;

void _start(void)
{
    /* copy data from rom */
    if (&__data_start != &__data_start_rom) {
        unsigned int *src = &__data_start_rom;
        unsigned int *dest = &__data_start;

        while (dest != &__data_end)
            *dest++ = *src++;
    }

    /* zero out bss */
    unsigned int *bss = &__bss_start;
    while (bss != &__bss_end)
        *bss++ = 0;

    lk_main();
}