xref: /illumos-gate/usr/src/contrib/ast/src/lib/libsum/sum-prng.c (revision b30d193948be5a7794d7ae3ba0ed9c2f72c88e0f)
1 /***********************************************************************
2 *                                                                      *
3 *               This software is part of the ast package               *
4 *          Copyright (c) 1996-2011 AT&T Intellectual Property          *
5 *                      and is licensed under the                       *
6 *                 Eclipse Public License, Version 1.0                  *
7 *                    by AT&T Intellectual Property                     *
8 *                                                                      *
9 *                A copy of the License is available at                 *
10 *          http://www.eclipse.org/org/documents/epl-v10.html           *
11 *         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *
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*
prng_open(const Method_t * method,const char * name)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
prng_init(Sum_t * p)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
prng_block(Sum_t * p,const void * s,size_t n)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 }
114