root/include/asm-i386/delay.h

/* */

INCLUDED FROM

DEFINITIONS

1. __delay
2. udelay
3. muldiv

   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 #ifdef __SMP__
  11 #include <asm/smp.h>
  12 #endif 
  13 
  14 extern __inline__ void __delay(int loops)
     /*  */
  15 {
  16         __asm__ __volatile__(
  17                 ".align 2,0x90\n1:\tdecl %0\n\tjns 1b"
  18                 :/* no outputs */
  19                 :"a" (loops)
  20                 :"ax");
  21 }
  22 
  23 /*
  24  * division by multiplication: you don't have to worry about
  25  * loss of precision.
  26  *
  27  * Use only for very small delays ( < 1 msec).  Should probably use a
  28  * lookup table, really, as the multiplications take much too long with
  29  * short delays.  This is a "reasonable" implementation, though (and the
  30  * first constant multiplications gets optimized away if the delay is
  31  * a constant)
  32  */
  33 extern __inline__ void udelay(unsigned long usecs)
     /*  */
  34 {
  35         usecs *= 0x000010c6;            /* 2**32 / 1000000 */
  36         __asm__("mull %0"
  37                 :"=d" (usecs)
  38 #ifdef __SMP__
  39                 :"a" (usecs),"0" (cpu_data[smp_processor_id()].udelay_val)
  40 #else
  41                 :"a" (usecs),"0" (loops_per_sec)
  42 #endif
  43                 :"ax");
  44                 
  45         __delay(usecs);
  46 }
  47 
  48 extern __inline__ unsigned long muldiv(unsigned long a, unsigned long b, unsigned long c)
     /*  */
  49 {
  50         __asm__("mull %1 ; divl %2"
  51                 :"=a" (a)
  52                 :"d" (b),
  53                  "r" (c),
  54                  "0" (a)
  55                 :"dx");
  56         return a;
  57 }
  58 
  59 #endif /* defined(_I386_DELAY_H) */

/* */