src/startup.c


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#define STACK_TOP 0x20005000


extern unsigned int _BSS_START;
extern unsigned int _BSS_END;
extern unsigned int _DATA_ROM_START;
extern unsigned int _DATA_RAM_START;
extern unsigned int _DATA_RAM_END;

void startup();
void main();

// Define the vector table
unsigned int * myvectors[2] 
__attribute__ ((section("vectors")))= {
    (unsigned int *)    STACK_TOP,  // stack pointer
    (unsigned int *)    startup     // code entry point
};

void startup()
{
    /* Set memory in bss segment to zeros */
    unsigned int * bss_start_p = &_BSS_START; 
    unsigned int * bss_end_p = &_BSS_END;

    while(bss_start_p != bss_end_p)
    {
        *bss_start_p = 0;
        bss_start_p++;
    }

    /* Copy memory in data segment from its position
     * in the flash image to its position in the
     * read/write memory */
    unsigned int * data_rom_start_p = &_DATA_ROM_START;
    unsigned int * data_ram_start_p = &_DATA_RAM_START;
    unsigned int * data_ram_end_p = &_DATA_RAM_END;

    while(data_ram_start_p != data_ram_end_p)
    {
        *data_ram_start_p = *data_rom_start_p;
        data_ram_start_p++;
        data_rom_start_p++;
    }

    /* Now we are ready to start the main function */
    main();
}