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      1 /*
      2  * Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
      3  *
      4  * Licensed under the Apache License 2.0 (the "License").  You may not use
      5  * this file except in compliance with the License.  You can obtain a copy
      6  * in the file LICENSE in the source distribution or at
      7  * https://www.openssl.org/source/license.html
      8  */
      9 
     10 #include <stddef.h>
     11 #include "internal/cryptlib.h"
     12 
     13 const void *ossl_bsearch(const void *key, const void *base, int num,
     14     int size, int (*cmp)(const void *, const void *),
     15     int flags)
     16 {
     17     const char *base_ = base;
     18     int l, h, i = 0, c = 0;
     19     const char *p = NULL;
     20 
     21     if (num == 0)
     22         return NULL;
     23     l = 0;
     24     h = num;
     25     while (l < h) {
     26         i = (l + h) / 2;
     27         p = &(base_[i * size]);
     28         c = (*cmp)(key, p);
     29         if (c < 0)
     30             h = i;
     31         else if (c > 0)
     32             l = i + 1;
     33         else
     34             break;
     35     }
     36     if (c != 0 && !(flags & OSSL_BSEARCH_VALUE_ON_NOMATCH))
     37         p = NULL;
     38     else if (c == 0 && (flags & OSSL_BSEARCH_FIRST_VALUE_ON_MATCH)) {
     39         while (i > 0 && (*cmp)(key, &(base_[(i - 1) * size])) == 0)
     40             i--;
     41         p = &(base_[i * size]);
     42     }
     43     return p;
     44 }
     45