compilers/linux86-0.16.17/libc/misc/bsearch.c

   1
   2 /*
   3  * This file lifted in toto from 'Dlibs' on the atari ST  (RdeBath)
   4  *
   5  *
   6  *    Dale Schumacher                         399 Beacon Ave.
   7  *    (alias: Dalnefre')                      St. Paul, MN  55104
   8  *    dal@syntel.UUCP                         United States of America
   9  *  "It's not reality that's important, but how you perceive things."
  10  */
  11 #include <stdio.h>
  12
  13 static int _bsearch;            /* index of element found, or where to
  14                                  * insert */
  15
  16 char *
  17 bsearch(key, base, num, size, cmp)
  18 register char *key;             /* item to search for */
  19 register char *base;            /* base address */
  20 int   num;                      /* number of elements */
  21 register int size;              /* element size in bytes */
  22 register int (*cmp) ();         /* comparison function */
  23 {
  24    register int a, b, c, dir;
  25
  26    a = 0;
  27    b = num - 1;
  28    while (a <= b)
  29    {
  30       c = (a + b) >> 1;         /* == ((a + b) / 2) */
  31       if (dir = (*cmp) ((base + (c * size)), key))
  32       {
  33          if (dir > 0)
  34             b = c - 1;
  35          else                   /* (dir < 0) */
  36             a = c + 1;
  37       }
  38       else
  39       {
  40          _bsearch = c;
  41          return (base + (c * size));
  42       }
  43    }
  44    _bsearch = b;
  45    return (NULL);
  46 }