usr/src/lib/libsum/common/sum-prng.c

   1 /***********************************************************************
   2 *                                                                      *
   3 *               This software is part of the ast package               *
   4 *          Copyright (c) 1996-2010 AT&T Intellectual Property          *
   5 *                      and is licensed under the                       *
   6 *                  Common Public License, Version 1.0                  *
   7 *                    by AT&T Intellectual Property                     *
   8 *                                                                      *
   9 *                A copy of the License is available at                 *
  10 *            http://www.opensource.org/licenses/cpl1.0.txt             *
  11 *         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
  12 *                                                                      *
  13 *              Information and Software Systems Research               *
  14 *                            AT&T Research                             *
  15 *                           Florham Park NJ                            *
  16 *                                                                      *
  17 *                 Glenn Fowler <gsf@research.att.com>                  *
  18 *                                                                      *
  19 ***********************************************************************/
  20 #pragma prototyped
  21
  22 /*
  23  * prng
  24  */
  25
  26 #include <fnv.h>
  27
  28 #define prng_description \
  29         "32 bit PRNG (pseudo random number generator) hash."
  30 #define prng_options    "\
  31 [+mpy?The 32 bit PRNG multiplier.]:[number:=0x01000193]\
  32 [+add?The 32 bit PRNG addend.]:[number:=0]\
  33 [+init?The PRNG initial value. 0xffffffff is used if \anumber\a is omitted.]:?[number:=0x811c9dc5]\
  34 "
  35 #define prng_match      "prng"
  36 #define prng_done       long_done
  37 #define prng_print      long_print
  38 #define prng_data       long_data
  39 #define prng_scale      0
  40
  41 typedef uint32_t Prngnum_t;
  42
  43 typedef struct Prng_s
  44 {
  45         _SUM_PUBLIC_
  46         _SUM_PRIVATE_
  47         _INTEGRAL_PRIVATE_
  48         Prngnum_t               init;
  49         Prngnum_t               mpy;
  50         Prngnum_t               add;
  51 } Prng_t;
  52
  53 static Sum_t*
  54 prng_open(const Method_t* method, const char* name)
  55 {
  56         register Prng_t*        sum;
  57         register const char*    s;
  58         register const char*    t;
  59         register const char*    v;
  60         register int            i;
  61
  62         if (sum = newof(0, Prng_t, 1, 0))
  63         {
  64                 sum->method = (Method_t*)method;
  65                 sum->name = name;
  66         }
  67         s = name;
  68         while (*(t = s))
  69         {
  70                 for (t = s, v = 0; *s && *s != '-'; s++)
  71                         if (*s == '=' && !v)
  72                                 v = s;
  73                 i = (v ? v : s) - t;
  74                 if (isdigit(*t) || v && strneq(t, "mpy", i) && (t = v + 1))
  75                         sum->mpy = strtoul(t, NiL, 0);
  76                 else if (strneq(t, "add", i))
  77                         sum->add = v ? strtoul(v + 1, NiL, 0) : ~sum->add;
  78                 else if (strneq(t, "init", i))
  79                         sum->init = v ? strtoul(v + 1, NiL, 0) : ~sum->init;
  80                 if (*s == '-')
  81                         s++;
  82         }
  83         if (!sum->mpy)
  84         {
  85                 sum->mpy = FNV_MULT;
  86                 if (!sum->init)
  87                         sum->init = FNV_INIT;
  88         }
  89         return (Sum_t*)sum;
  90 }
  91
  92 static int
  93 prng_init(Sum_t* p)
  94 {
  95         Prng_t*         sum = (Prng_t*)p;
  96
  97         sum->sum = sum->init;
  98         return 0;
  99 }
 100
 101 static int
 102 prng_block(Sum_t* p, const void* s, size_t n)
 103 {
 104         Prng_t*                 sum = (Prng_t*)p;
 105         register Prngnum_t      c = sum->sum;
 106         register unsigned char* b = (unsigned char*)s;
 107         register unsigned char* e = b + n;
 108
 109         while (b < e)
 110                 c = c * sum->mpy + sum->add + *b++;
 111         sum->sum = c;
 112         return 0;
 113 }