root/include/asm-m68k/delay.h

/* */

INCLUDED FROM

DEFINITIONS

1. __delay
2. udelay

   1 #ifndef _M68K_DELAY_H
   2 #define _M68K_DELAY_H
   3 
   4 /*
   5  * Copyright (C) 1994 Hamish Macdonald
   6  *
   7  * Delay routines, using a pre-computed "loops_per_second" value.
   8  */
   9 
  10 extern __inline__ void __delay(int loops)
     /*  */
  11 {
  12         __asm__("\n\tmovel %0,d0\n1:\tsubql #1,d0\n\tbpls 1b\n"
  13                 : /* no outputs */
  14                 : "g" (loops)
  15                 : "d0");
  16 }
  17 
  18 /*
  19  * division by multiplication: you don't have to worry about
  20  * loss of precision.
  21  *
  22  * Use only for very small delays ( < 1 msec).  Should probably use a
  23  * lookup table, really, as the multiplications take much too long with
  24  * short delays.  This is a "reasonable" implementation, though (and the
  25  * first constant multiplications gets optimized away if the delay is
  26  * a constant)  
  27  */
  28 extern __inline__ void udelay(unsigned long usecs)
     /*  */
  29 {
  30         asm ("mulul %1,d0,%0\n\t"
  31              "divul  %2,d0,%0"
  32              : "=d" (usecs)
  33              : "d" (usecs),
  34                "i" (1000000),
  35                "0" (loops_per_sec)
  36              : "d0");
  37         __delay(usecs);
  38 }
  39 
  40 #endif /* defined(_M68K_DELAY_H) */

/* */