hash.h

   1 /*
   2  * Copyright (C) 2007-2010 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file hash.h Inline functions for hash values. */
   8
   9 /** hash arrays are always unsigned char. */
  10 #define HASH_TYPE unsigned char
  11
  12 #include "sha1.h"
  13 /** We use openssl's sha1 implementation. */
  14 #define hash_function sha1_hash
  15
  16 /**
  17  * Compare two hashes.
  18  *
  19  * \param h1 Pointer to the first hash value.
  20  * \param h2 Pointer to the second hash value.
  21  *
  22  * \return 1, -1, or zero, depending on whether \a h1 is greater than,
  23  * less than or equal to h2, respectively.
  24  */
  25 _static_inline_ int hash_compare(HASH_TYPE *h1, HASH_TYPE *h2)
  26 {
  27         int i;
  28
  29         for (i = 0; i < HASH_SIZE; i++) {
  30                 if (h1[i] < h2[i])
  31                         return -1;
  32                 if (h1[i] > h2[i])
  33                         return 1;
  34         }
  35         return 0;
  36 }
  37
  38 /**
  39  * Convert a hash value to ascii format.
  40  *
  41  * \param hash the hash value.
  42  * \param asc Result pointer.
  43  *
  44  * \a asc must point to an area of at least 2 * \p HASH_SIZE + 1 bytes which
  45  * will be filled by the function with the ascii representation of the hash
  46  * value given by \a hash, and a terminating \p NULL byte.
  47  */
  48 _static_inline_ void hash_to_asc(HASH_TYPE *hash, char *asc)
  49 {
  50         int i;
  51         const char hexchar[] = "0123456789abcdef";
  52
  53         for (i = 0; i < HASH_SIZE; i++) {
  54                 asc[2 * i] = hexchar[hash[i] >> 4];
  55                 asc[2 * i + 1] = hexchar[hash[i] & 0xf];
  56         }
  57         asc[2 * HASH_SIZE] = '\0';
  58 }