void init()
{
    asm(
        "bl get_r2;"
        "get_r2:;"
        "mflr 3;"
        "lis %r4, get_r2@toc@h;"
        "ori %r4, %r4, get_r2@toc@l;"
        "sldi %r4, %r4, 32;"
        "sradi %r4, %r4, 32;"
        "sub %r2, %r3, %r4;"
        "addi %r2,%r2,0x7000;"
        "addi %r2,%r2,0x1000;"
    );
}