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gerrit.opencord.org / quagga / 821df2cf18e5978cc7ab532a8695444380d08270 / . / isisd / topology / random.c
blob: 2c457c52ca56982a717c701f2ffb96c2169727cd [file] [log] [blame]
jardineb5d44e2003-12-23 08:09:43 +0000[diff] [blame]1/*********************************************************************/
2/* */
3/* current processor time in seconds */
4/* difference between two calls is processor time spent by your code */
5/* needs: <sys/types.h>, <sys/times.h> */
6/* depends on compiler and OS */
7/* */
8/*********************************************************************/
9
David Lamparter821df2c2015-09-15 01:53:09 -0700[diff] [blame^]10#include <zebra.h>
jardineb5d44e2003-12-23 08:09:43 +0000[diff] [blame]11#include <sys/types.h>
12#include <sys/times.h>
13
Paul Jakma41b36e92006-12-08 01:09:50 +0000[diff] [blame]14/*
15 * Prototypes.
16 */
17unsigned long timer(void);
18void init_rand(long);
19double rand01(void);
20double randg01(void);
21long nrand(long);
22void free_arc(void *);
23
24unsigned long timer ()
jardineb5d44e2003-12-23 08:09:43 +0000[diff] [blame]25 { struct tms hold;
26
27 times(&hold);
hasso29e50b22005-09-01 18:18:47 +0000[diff] [blame]28 return (unsigned long) ((float) (hold.tms_utime) / 60.0);
jardineb5d44e2003-12-23 08:09:43 +0000[diff] [blame]29 }
30
31
32/*********************************************************************/
33/* */
34/* Family of random number generators */
35/* */
36/* Initialisation: */
37/* void init_rand ( seed ); */
38/* long seed - any positive number */
39/* if seed<=0 init_rand takes time */
40/* from timer instead of seed */
41/* */
42/* Whole number uniformly distributed on [0,n): */
43/* long nrand (n); */
44/* long n */
45/* */
46/* Real number uniformly distributed on [0,1] */
47/* double rand01(); */
48/* */
49/* Real number with Gauss(0,1) disitribution: */
50/* double randg01(); */
51/* */
52/* Algorithm: */
53/* x(n+1) = (x(n) * 5^13) mod 2^31 */
54/* */
55/*********************************************************************/
56
57unsigned long internal_seed;
58
59void init_rand ( init_seed )
60
61long init_seed;
62
63{ internal_seed = ( init_seed > 0 )
64 ? (unsigned long) init_seed
65 : (unsigned long) timer();
66
67
68 /* only odd numbers are acceptable */
69 if ( internal_seed % 2 == 0 ) internal_seed --;
70}
71
72/*********************************************************************/
73/* */
74/* Internal function irand may depend on OS and compiler */
75/* */
76/* irand assumption: */
77/* unsigned long i,j; */
78/* if i*j > max(unsigned long) */
79/* 1. No overflow interruption */
80/* 2. i*j = i*j mod max(unsigned long) */
81/* */
82/* This assumption is true for a lot of computers. */
83/* If your computer fails: */
84/* rename: irand <---> xrand */
85/* */
86/*********************************************************************/
87
88#define A 1220703125
89#define B 2147483647
90#define BF 2147483647.
91
92static long irand ()
93
94{ internal_seed = ( internal_seed * A ) & B;
95 return (long) internal_seed ;
96}
97
hasso29e50b22005-09-01 18:18:47 +0000[diff] [blame]98#if 0 /* Not used. */
jardineb5d44e2003-12-23 08:09:43 +0000[diff] [blame]99/*********************************************************************/
100/* */
101/* computer independent variant of irand */
102/* */
103/*********************************************************************/
104
105
106#define T15 32768
107#define T16 65536
108#define A1 37252
109#define A2 29589
110
111static long xrand()
112
113{ unsigned long is1, is2;
114
115 is1 = internal_seed / T15;
116 is2 = internal_seed % T15;
117
118 internal_seed = ( (((is2 * A1) + (is1 * A2))% T16 )* T15 + (is2 * A2) ) & B;
119 return (long) ( internal_seed ) ;
120}
hasso29e50b22005-09-01 18:18:47 +0000[diff] [blame]121#endif
jardineb5d44e2003-12-23 08:09:43 +0000[diff] [blame]122
123/*********************************************************************/
124
125
126double rand01()
127
hasso29e50b22005-09-01 18:18:47 +0000[diff] [blame]128{ return (double) (irand() / BF) ;
jardineb5d44e2003-12-23 08:09:43 +0000[diff] [blame]129}
130
131/*********************************************************************/
132
133#define NK 12
134
135double randg01()
136
137{ int i;
138 double sum = 0;
139
140 for ( i = 0; i < NK; i++ ) sum += rand01();
141 return sum - 6.;
142
143 /* if NK != 12 then you must return (12/NK)*sum - (NK/2) */
144}
145
146#undef NK
147
148
149/*********************************************************************/
150
151long nrand ( n )
152
153long n;
154
155{ return (long) ( rand01() * (double) n );
156}
157
158/*********************************************************************/
159
160#undef A
161#undef A1
162#undef A2
163#undef B
164#undef BF
165#undef T15
166#undef T16