/*
 * Standard __asm__ format:
 *
 *  __asm__(
 *          "command;"
 *          "command;"
 *          "command;"
 *      :   "=r"(_res)          return value, in register
 *      :   "r"(lock)           argument, 'lock pointer', in register
 *      :   "r0");              inline code uses this register
 */