LXR linux/include/asm-m68k/delay.h

   1#ifndef _M68K_DELAY_H
   2#define _M68K_DELAY_H
   3
   4#include <asm/param.h>
   5
   6/*
   7 * Copyright (C) 1994 Hamish Macdonald
   8 *
   9 * Delay routines, using a pre-computed "loops_per_jiffy" value.
  10 */
  11
  12static inline void __delay(unsigned long loops)
  13{
  14        __asm__ __volatile__ ("1: subql #1,%0; jcc 1b"
  15                : "=d" (loops) : "0" (loops));
  16}
  17
  18extern void __bad_udelay(void);
  19
  20/*
  21 * Use only for very small delays ( < 1 msec).  Should probably use a
  22 * lookup table, really, as the multiplications take much too long with
  23 * short delays.  This is a "reasonable" implementation, though (and the
  24 * first constant multiplications gets optimized away if the delay is
  25 * a constant)
  26 */
  27static inline void __const_udelay(unsigned long xloops)
  28{
  29        unsigned long tmp;
  30
  31        __asm__ ("mulul %2,%0:%1"
  32                : "=d" (xloops), "=d" (tmp)
  33                : "d" (xloops), "1" (loops_per_jiffy));
  34        __delay(xloops * HZ);
  35}
  36
  37static inline void __udelay(unsigned long usecs)
  38{
  39        __const_udelay(usecs * 4295);   /* 2**32 / 1000000 */
  40}
  41
  42#define udelay(n) (__builtin_constant_p(n) ? \
  43        ((n) > 20000 ? __bad_udelay() : __const_udelay((n) * 4295)) : \
  44        __udelay(n))
  45
  46static inline unsigned long muldiv(unsigned long a, unsigned long b,
  47                                   unsigned long c)
  48{
  49        unsigned long tmp;
  50
  51        __asm__ ("mulul %2,%0:%1; divul %3,%0:%1"
  52                : "=d" (tmp), "=d" (a)
  53                : "d" (b), "d" (c), "1" (a));
  54        return a;
  55}
  56
  57#endif /* defined(_M68K_DELAY_H) */
  58