source: trunk/libs/newlib/src/libgloss/sparc_leon/asm-leon/jiffies.h @ 444

/*
 * Copyright (c) 2011 Aeroflex Gaisler
 *
 * BSD license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */


#ifndef _LINUX_JIFFIES_H
#define _LINUX_JIFFIES_H

#include <asm-leon/types.h>
#include <asm-leon/clock.h>
#include <asm-leon/linkage.h>

/* Suppose we want to devide two numbers NOM and DEN: NOM/DEN, the we can
 * improve accuracy by shifting LSH bits, hence calculating:
 *     (NOM << LSH) / DEN
 * This however means trouble for large NOM, because (NOM << LSH) may no
 * longer fit in 32 bits. The following way of calculating this gives us
 * some slack, under the following conditions:
 *   - (NOM / DEN) fits in (32 - LSH) bits.
 *   - (NOM % DEN) fits in (32 - LSH) bits.
 */
#define SH_DIV(NOM,DEN,LSH) (   ((NOM / DEN) << LSH)                    \
                             + (((NOM % DEN) << LSH) + DEN / 2) / DEN)

/* TICK_NSEC is the time between ticks in nsec assuming real ACTHZ */
#define TICK_NSEC (SH_DIV (1000000UL * 1000, (HZ<<8), 8))

/*
 * The 64-bit value is not volatile - you MUST NOT read it
 * without sampling the sequence number in xtime_lock.
 */
extern u64 jiffies_64;
extern struct timespec xtime __attribute__ ((aligned (16)));
#define jiffies (*((unsigned long *)(((unsigned long)(&jiffies_64))+4)))

/*
 *      These inlines deal with timer wrapping correctly. You are 
 *      strongly encouraged to use them
 *      1. Because people otherwise forget
 *      2. Because if the timer wrap changes in future you won't have to
 *         alter your driver code.
 *
 * time_after(a,b) returns true if the time a is after time b.
 *
 * Do this with "<0" and ">=0" to only test the sign of the result. A
 * good compiler would generate better code (and a really good compiler
 * wouldn't care). Gcc is currently neither.
 */
#define time_after(a,b)         \
        (typecheck(unsigned long, a) && \
         typecheck(unsigned long, b) && \
         ((long)(b) - (long)(a) < 0))
#define time_before(a,b)        time_after(b,a)

#define time_after_eq(a,b)      \
        (typecheck(unsigned long, a) && \
         typecheck(unsigned long, b) && \
         ((long)(a) - (long)(b) >= 0))
#define time_before_eq(a,b)     time_after_eq(b,a)

/*
 * Have the 32 bit jiffies value wrap 5 minutes after boot
 * so jiffies wrap bugs show up earlier.
 */
#define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ))

static inline void
set_normalized_timespec (struct timespec *ts, time_t sec, long nsec)
{
  while (nsec > NSEC_PER_SEC)
    {
      nsec -= NSEC_PER_SEC;
      ++sec;
    }
  while (nsec < 0)
    {
      nsec += NSEC_PER_SEC;
      --sec;
    }
  ts->tv_sec = sec;
  ts->tv_nsec = nsec;
}

#endif