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      1 /*
      2  * ut_sim.c
      3  *
      4  * an unreliable transport simulator
      5  * (for testing replay databases and suchlike)
      6  *
      7  * David A. McGrew
      8  * Cisco Systems, Inc.
      9  */
     10 
     11 /*
     12  *
     13  * Copyright (c) 2001-2006, Cisco Systems, Inc.
     14  * All rights reserved.
     15  *
     16  * Redistribution and use in source and binary forms, with or without
     17  * modification, are permitted provided that the following conditions
     18  * are met:
     19  *
     20  *   Redistributions of source code must retain the above copyright
     21  *   notice, this list of conditions and the following disclaimer.
     22  *
     23  *   Redistributions in binary form must reproduce the above
     24  *   copyright notice, this list of conditions and the following
     25  *   disclaimer in the documentation and/or other materials provided
     26  *   with the distribution.
     27  *
     28  *   Neither the name of the Cisco Systems, Inc. nor the names of its
     29  *   contributors may be used to endorse or promote products derived
     30  *   from this software without specific prior written permission.
     31  *
     32  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     33  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     34  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     35  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
     36  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
     37  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     38  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
     39  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     40  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
     41  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     42  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
     43  * OF THE POSSIBILITY OF SUCH DAMAGE.
     44  *
     45  */
     46 
     47 
     48 #include "ut_sim.h"
     49 
     50 
     51 int
     52 ut_compar(const void *a, const void *b) {
     53   return rand() > (RAND_MAX/2) ? -1 : 1;
     54 }
     55 
     56 void
     57 ut_init(ut_connection *utc) {
     58   int i;
     59   utc->index = 0;
     60 
     61   for (i=0; i < UT_BUF; i++)
     62     utc->buffer[i] = i;
     63 
     64   qsort(utc->buffer, UT_BUF, sizeof(uint32_t), ut_compar);
     65 
     66   utc->index = UT_BUF - 1;
     67 }
     68 
     69 uint32_t
     70 ut_next_index(ut_connection *utc) {
     71   uint32_t tmp;
     72 
     73   tmp = utc->buffer[0];
     74   utc->index++;
     75   utc->buffer[0] = utc->index;
     76 
     77   qsort(utc->buffer, UT_BUF, sizeof(uint32_t), ut_compar);
     78 
     79   return tmp;
     80 }
     81 
     82 
     83 
     84 #ifdef UT_TEST
     85 
     86 #include <stdio.h>
     87 
     88 int
     89 main() {
     90   uint32_t i, irecvd, idiff;
     91   ut_connection utc;
     92 
     93   ut_init(&utc);
     94 
     95   for (i=0; i < 1000; i++) {
     96     irecvd = ut_next_index(&utc);
     97     idiff = i - irecvd;
     98     printf("%lu\t%lu\t%d\n", i, irecvd, idiff);
     99   }
    100 
    101   return 0;
    102 }
    103 
    104 
    105 #endif
    106