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__(".align 2,0x90\n1:\tdecl %0\n\tjns 1b": :"a" (loops):"ax");
  17 }
  18 
  19 /*
  20  * division by multiplication: you don't have to worry about
  21  * loss of precision.
  22  *
  23  * Use only for very small delays ( < 1 msec).  Should probably use a
  24  * lookup table, really, as the multiplications take much too long with
  25  * short delays.  This is a "reasonable" implementation, though (and the
  26  * first constant multiplications gets optimized away if the delay is
  27  * a constant)
  28  */
  29 extern __inline__ void udelay(unsigned long usecs)
     /*  */
  30 {
  31         usecs *= 0x000010c6;            /* 2**32 / 1000000 */
  32         __asm__("mull %0"
  33                 :"=d" (usecs)
  34 #ifdef __SMP__
  35                 :"a" (usecs),"0" (cpu_data[smp_processor_id()].udelay_val)
  36 #else
  37                 :"a" (usecs),"0" (loops_per_sec)
  38 #endif
  39                 :"ax");
  40                 
  41         __delay(usecs);
  42 }
  43 
  44 extern __inline__ unsigned long muldiv(unsigned long a, unsigned long b, unsigned long c)
     /*  */
  45 {
  46         __asm__("mull %1 ; divl %2"
  47                 :"=a" (a)
  48                 :"d" (b),
  49                  "r" (c),
  50                  "0" (a)
  51                 :"dx");
  52         return a;
  53 }
  54 
  55 #endif /* defined(_I386_DELAY_H) */

/* */