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      1 /* lzo_util.c -- utilities for the LZO library
      2 
      3    This file is part of the LZO real-time data compression library.
      4 
      5    Copyright (C) 1996-2014 Markus Franz Xaver Johannes Oberhumer
      6    All Rights Reserved.
      7 
      8    The LZO library is free software; you can redistribute it and/or
      9    modify it under the terms of the GNU General Public License as
     10    published by the Free Software Foundation; either version 2 of
     11    the License, or (at your option) any later version.
     12 
     13    The LZO library is distributed in the hope that it will be useful,
     14    but WITHOUT ANY WARRANTY; without even the implied warranty of
     15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     16    GNU General Public License for more details.
     17 
     18    You should have received a copy of the GNU General Public License
     19    along with the LZO library; see the file COPYING.
     20    If not, write to the Free Software Foundation, Inc.,
     21    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
     22 
     23    Markus F.X.J. Oberhumer
     24    <markus (at) oberhumer.com>
     25    http://www.oberhumer.com/opensource/lzo/
     26  */
     27 
     28 
     29 #include "lzo_conf.h"
     30 
     31 
     32 /***********************************************************************
     33 //
     34 ************************************************************************/
     35 
     36 /* If you use the LZO library in a product, I would appreciate that you
     37  * keep this copyright string in the executable of your product.
     38 .*/
     39 
     40 static const char __lzo_copyright[] =
     41 #if !defined(__LZO_IN_MINLZO)
     42     /* save space as some people want a really small decompressor */
     43     LZO_VERSION_STRING;
     44 #else
     45     "\r\n\n"
     46     "LZO data compression library.\n"
     47     "$Copyright: LZO Copyright (C) 1996-2014 Markus Franz Xaver Johannes Oberhumer\n"
     48     "<markus (at) oberhumer.com>\n"
     49     "http://www.oberhumer.com $\n\n"
     50     "$Id: LZO version: v" LZO_VERSION_STRING ", " LZO_VERSION_DATE " $\n"
     51     "$Info: " LZO_INFO_STRING " $\n";
     52 #endif
     53 
     54 
     55 LZO_PUBLIC(const lzo_bytep)
     56 lzo_copyright(void)
     57 {
     58     return (const lzo_bytep) __lzo_copyright;
     59 }
     60 
     61 LZO_PUBLIC(unsigned)
     62 lzo_version(void)
     63 {
     64     return LZO_VERSION;
     65 }
     66 
     67 LZO_PUBLIC(const char *)
     68 lzo_version_string(void)
     69 {
     70     return LZO_VERSION_STRING;
     71 }
     72 
     73 LZO_PUBLIC(const char *)
     74 lzo_version_date(void)
     75 {
     76     return LZO_VERSION_DATE;
     77 }
     78 
     79 LZO_PUBLIC(const lzo_charp)
     80 _lzo_version_string(void)
     81 {
     82     return LZO_VERSION_STRING;
     83 }
     84 
     85 LZO_PUBLIC(const lzo_charp)
     86 _lzo_version_date(void)
     87 {
     88     return LZO_VERSION_DATE;
     89 }
     90 
     91 
     92 /***********************************************************************
     93 // adler32 checksum
     94 // adapted from free code by Mark Adler <madler (at) alumni.caltech.edu>
     95 // see http://www.zlib.org/
     96 ************************************************************************/
     97 
     98 #define LZO_BASE 65521u /* largest prime smaller than 65536 */
     99 #define LZO_NMAX 5552
    100 /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
    101 
    102 #define LZO_DO1(buf,i)  s1 += buf[i]; s2 += s1
    103 #define LZO_DO2(buf,i)  LZO_DO1(buf,i); LZO_DO1(buf,i+1);
    104 #define LZO_DO4(buf,i)  LZO_DO2(buf,i); LZO_DO2(buf,i+2);
    105 #define LZO_DO8(buf,i)  LZO_DO4(buf,i); LZO_DO4(buf,i+4);
    106 #define LZO_DO16(buf,i) LZO_DO8(buf,i); LZO_DO8(buf,i+8);
    107 
    108 LZO_PUBLIC(lzo_uint32_t)
    109 lzo_adler32(lzo_uint32_t adler, const lzo_bytep buf, lzo_uint len)
    110 {
    111     lzo_uint32_t s1 = adler & 0xffff;
    112     lzo_uint32_t s2 = (adler >> 16) & 0xffff;
    113     unsigned k;
    114 
    115     if (buf == NULL)
    116         return 1;
    117 
    118     while (len > 0)
    119     {
    120         k = len < LZO_NMAX ? (unsigned) len : LZO_NMAX;
    121         len -= k;
    122         if (k >= 16) do
    123         {
    124             LZO_DO16(buf,0);
    125             buf += 16;
    126             k -= 16;
    127         } while (k >= 16);
    128         if (k != 0) do
    129         {
    130             s1 += *buf++;
    131             s2 += s1;
    132         } while (--k > 0);
    133         s1 %= LZO_BASE;
    134         s2 %= LZO_BASE;
    135     }
    136     return (s2 << 16) | s1;
    137 }
    138 
    139 #undef LZO_DO1
    140 #undef LZO_DO2
    141 #undef LZO_DO4
    142 #undef LZO_DO8
    143 #undef LZO_DO16
    144 
    145 
    146 /*
    147 vi:ts=4:et
    148 */
    149