| NingSun | 0c89b3c | 2018-02-08 08:34:03 -0800 | [diff] [blame] | 1 | /* This code was taken from http://www.fourmilab.ch/random/ where it states that: |
| 2 | |
| 3 | This software is in the public domain. Permission to use, copy, modify, and distribute |
| 4 | this software and its documentation for any purpose and without fee is hereby granted, |
| 5 | without any conditions or restrictions. This software is provided “as is” without |
| 6 | express or implied warranty. */ |
| 7 | |
| 8 | /* |
| 9 | ENT -- Entropy calculation and analysis of putative |
| 10 | random sequences. |
| 11 | |
| 12 | Designed and implemented by John "Random" Walker in May 1985. |
| 13 | |
| 14 | Multiple analyses of random sequences added in December 1985. |
| 15 | |
| 16 | Bit stream analysis added in September 1997. |
| 17 | |
| 18 | Terse mode output, getopt() command line processing, |
| 19 | optional stdin input, and HTML documentation added in |
| 20 | October 1998. |
| 21 | |
| 22 | Documentation for the -t (terse output) option added |
| 23 | in July 2006. |
| 24 | |
| 25 | Replaced table look-up for chi square to probability |
| 26 | conversion with algorithmic computation in January 2008. |
| 27 | |
| 28 | For additional information and the latest version, |
| 29 | see http://www.fourmilab.ch/random/ |
| 30 | |
| 31 | */ |
| 32 | |
| 33 | #include <stdio.h> |
| 34 | #include <string.h> |
| 35 | #include <ctype.h> |
| 36 | #include <math.h> |
| 37 | #ifdef _WIN32 |
| 38 | #include <fcntl.h> |
| 39 | #include <io.h> |
| 40 | #else |
| 41 | #include <unistd.h> |
| 42 | #endif |
| 43 | |
| 44 | #include "iso8859.h" |
| 45 | #include "randtest.h" |
| 46 | |
| 47 | #define UPDATE "January 28th, 2008" |
| 48 | |
| 49 | #define FALSE 0 |
| 50 | #define TRUE 1 |
| 51 | |
| 52 | #ifdef M_PI |
| 53 | #define PI M_PI |
| 54 | #else |
| 55 | #define PI 3.14159265358979323846 |
| 56 | #endif |
| 57 | |
| 58 | extern double pochisq(const double ax, const int df); |
| 59 | |
| 60 | /* Main program */ |
| 61 | |
| 62 | void doEnt |
| 63 | ( |
| 64 | unsigned char* data, |
| 65 | size_t len, |
| 66 | double* pEntropy, |
| 67 | double* pChiProbability, |
| 68 | double* pArithMean, |
| 69 | double* pMontePi, |
| 70 | double* pSerialCorrelation |
| 71 | ) |
| 72 | { |
| 73 | size_t s; |
| 74 | long ccount[256]; /* Bins to count occurrences of values */ |
| 75 | double montepi, chip, |
| 76 | scc, ent, mean, chisq; |
| 77 | |
| 78 | /* Initialise for calculations */ |
| 79 | |
| 80 | rt_init(FALSE); |
| 81 | |
| 82 | /* Scan input file and count character occurrences */ |
| 83 | |
| 84 | for (s = 0; s < len; s++) |
| 85 | { |
| 86 | unsigned char ocb = data[s]; |
| 87 | |
| 88 | ccount[ocb]++; /* Update counter for this bin */ |
| 89 | rt_add(&ocb, 1); |
| 90 | } |
| 91 | |
| 92 | /* Complete calculation and return sequence metrics */ |
| 93 | |
| 94 | rt_end(&ent, &chisq, &mean, &montepi, &scc); |
| 95 | |
| 96 | /* Calculate probability of observed distribution occurring from |
| 97 | the results of the Chi-Square test */ |
| 98 | |
| 99 | chip = pochisq(chisq, 255); |
| 100 | |
| 101 | /* Print bin counts if requested */ |
| 102 | |
| 103 | /* Return calculated results */ |
| 104 | |
| 105 | *pEntropy = ent; |
| 106 | *pChiProbability = chip; |
| 107 | *pArithMean = mean; |
| 108 | *pMontePi = montepi; |
| 109 | *pSerialCorrelation = scc; |
| 110 | } |