1  /*
       2    Parameters for the Linux kernel ABI for CPU clocks, the bit fields within
       3    a clockid:
       4  
       5    - The most significant 29 bits hold either a pid or a file descriptor.
       6    - Bit 2 indicates whether a cpu clock refers to a thread or a process.
       7    - Bits 1 and 0 give the type: PROF=0, VIRT=1, SCHED=2, or FD=3.
       8    - A clockid is invalid if bits 2, 1, and 0 are all set.
       9   */
      10  
      11  #define CPUCLOCK_PID(clock)		((pid_t) ~((clock) >> 3))
      12  #define CPUCLOCK_PERTHREAD(clock) \
      13  	(((clock) & (clockid_t) CPUCLOCK_PERTHREAD_MASK) != 0)
      14  #define CPUCLOCK_PID_MASK	7
      15  #define CPUCLOCK_PERTHREAD_MASK	4
      16  #define CPUCLOCK_WHICH(clock)	((clock) & (clockid_t) CPUCLOCK_CLOCK_MASK)
      17  #define CPUCLOCK_CLOCK_MASK	3
      18  #define CPUCLOCK_PROF		0
      19  #define CPUCLOCK_VIRT		1
      20  #define CPUCLOCK_SCHED		2
      21  #define CPUCLOCK_MAX		3
      22  
      23  static inline clockid_t
      24  make_process_cpuclock (unsigned int pid, clockid_t clock)
      25  {
      26    return ((~pid) << 3) | clock;
      27  }
      28  
      29  static inline clockid_t
      30  make_thread_cpuclock (unsigned int tid, clockid_t clock)
      31  {
      32    return make_process_cpuclock (tid, clock | CPUCLOCK_PERTHREAD_MASK);
      33  }
      34  
      35  #define PROCESS_CLOCK  make_process_cpuclock (0, CPUCLOCK_SCHED)
      36  #define THREAD_CLOCK   make_thread_cpuclock (0, CPUCLOCK_SCHED)