FENIX_libc/stdlib/bsearch.c

/*
 * bsearch - binary search!
 *
 * This header is a part of the FENIX C Library and is free software.
 * You can redistribute and/or modify it subject to the terms of the
 * Clumsy Wolf Public License v4. For more details, see the file COPYING.
 *
 * The FENIX C Library is distributed WITH NO WARRANTY WHATSOEVER. See
 * The CWPL for more details.
 */

#include <stdlib.h>

void * bsearch(const void * key, const void * base, size_t nel, size_t width,
               int (*compar)(const void *, const void*)) {
  void * left; 
  void * right;
  void * mid;

  if(nel == 0 || base == NULL) {
    return NULL;
  }

  left = base;
  right = base + (nel * width);

  while(left <= right) {
    mid = (left + right) / 2;
    int t = compar(key, mid);
    if(t == 0) {
      return mid;
    }
    else if(t < 0) {
      right = mid - width;
    }
    else if(t > 0) {
      left = mid + width;
    }
  }

  return NULL;
}