LXR linux-bk/include/linux/jiffies.h

   1#ifndef _LINUX_JIFFIES_H
   2#define _LINUX_JIFFIES_H
   3
   4#include <linux/kernel.h>
   5#include <linux/types.h>
   6#include <linux/spinlock.h>
   7#include <linux/seqlock.h>
   8#include <asm/system.h>
   9#include <asm/param.h>                  /* for HZ */
  10
  11/*
  12 * The 64-bit value is not volatile - you MUST NOT read it
  13 * without sampling the sequence number in xtime_lock.
  14 * get_jiffies_64() will do this for you as appropriate.
  15 */
  16extern u64 jiffies_64;
  17extern unsigned long volatile jiffies;
  18
  19#if (BITS_PER_LONG < 64)
  20u64 get_jiffies_64(void);
  21#else
  22static inline u64 get_jiffies_64(void)
  23{
  24        return (u64)jiffies;
  25}
  26#endif
  27
  28/*
  29 *      These inlines deal with timer wrapping correctly. You are 
  30 *      strongly encouraged to use them
  31 *      1. Because people otherwise forget
  32 *      2. Because if the timer wrap changes in future you won't have to
  33 *         alter your driver code.
  34 *
  35 * time_after(a,b) returns true if the time a is after time b.
  36 *
  37 * Do this with "<0" and ">=0" to only test the sign of the result. A
  38 * good compiler would generate better code (and a really good compiler
  39 * wouldn't care). Gcc is currently neither.
  40 */
  41#define time_after(a,b)         \
  42        (typecheck(unsigned long, a) && \
  43         typecheck(unsigned long, b) && \
  44         ((long)(b) - (long)(a) < 0))
  45#define time_before(a,b)        time_after(b,a)
  46
  47#define time_after_eq(a,b)      \
  48        (typecheck(unsigned long, a) && \
  49         typecheck(unsigned long, b) && \
  50         ((long)(a) - (long)(b) >= 0))
  51#define time_before_eq(a,b)     time_after_eq(b,a)
  52
  53#endif
  54