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*
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