root/include/asm-i386/delay.h

/* */

INCLUDED FROM

DEFINITIONS

1. __delay
2. udelay

   1 #ifndef _I386_DELAY_H
   2 #define _I386_DELAY_H
   3 
   4 /*
   5  * Copyright (C) 1993 Linus Torvalds
   6  *
   7  * Delay routines, using a pre-computed "loops_per_second" value.
   8  */
   9 
  10 extern __inline__ void __delay(int loops)
     /*  */
  11 {
  12         __asm__(".align 2,0x90\n1:\tdecl %0\n\tjns 1b": :"a" (loops):"ax");
  13 }
  14 
  15 /*
  16  * division by multiplication: you don't have to worry about
  17  * loss of precision.
  18  *
  19  * Use only for very small delays ( < 1 msec).  Should probably use a
  20  * lookup table, really, as the multiplications take much too long with
  21  * short delays.  This is a "reasonable" implementation, though (and the
  22  * first constant multiplications gets optimized away if the delay is
  23  * a constant)
  24  */
  25 extern __inline__ void udelay(unsigned long usecs)
     /*  */
  26 {
  27         usecs *= 0x000010c6;            /* 2**32 / 1000000 */
  28         __asm__("mull %0"
  29                 :"=d" (usecs)
  30                 :"a" (usecs),"0" (loops_per_sec)
  31                 :"ax");
  32         __delay(usecs);
  33 }
  34 
  35 #endif /* defined(_I386_DELAY_H) */

/* */