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authorNingSun <ning.sun@intel.com>2018-02-08 08:34:03 -0800
committerNingSun <ning.sun@intel.com>2018-02-08 09:14:52 -0800
commit0c89b3ccba7c9b7332ab67ae1936aff51ca62367 (patch)
tree70c1b1d160d4c6d0a83395ca9a87c1264d0d3439 /SoftHSMv2/src/lib/crypto/test/chisq.c
parent945613b4db4e07f75d2bc7463db580ddfaa700fd (diff)
Initial sshsm project structure
Issue-ID: AAF-94 Change-Id: I5e82fff418e7567b161acf9b98013a9b85ffc5b4 Signed-off-by: NingSun <ning.sun@intel.com>
Diffstat (limited to 'SoftHSMv2/src/lib/crypto/test/chisq.c')
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+/* This code was taken from http://www.fourmilab.ch/random/ where it states that:
+
+ This software is in the public domain. Permission to use, copy, modify, and distribute
+ this software and its documentation for any purpose and without fee is hereby granted,
+ without any conditions or restrictions. This software is provided “as is” without
+ express or implied warranty. */
+
+/*
+
+ Compute probability of measured Chi Square value.
+
+ This code was developed by Gary Perlman of the Wang
+ Institute (full citation below) and has been minimally
+ modified for use in this program.
+
+*/
+
+#include <math.h>
+
+/*HEADER
+ Module: z.c
+ Purpose: compute approximations to normal z distribution probabilities
+ Programmer: Gary Perlman
+ Organization: Wang Institute, Tyngsboro, MA 01879
+ Copyright: none
+ Tabstops: 4
+*/
+
+#define Z_MAX 6.0 /* maximum meaningful z value */
+
+/*FUNCTION poz: probability of normal z value */
+/*ALGORITHM
+ Adapted from a polynomial approximation in:
+ Ibbetson D, Algorithm 209
+ Collected Algorithms of the CACM 1963 p. 616
+ Note:
+ This routine has six digit accuracy, so it is only useful for absolute
+ z values < 6. For z values >= to 6.0, poz() returns 0.0.
+*/
+static double /*VAR returns cumulative probability from -oo to z */
+poz(const double z) /*VAR normal z value */
+{
+ double y, x, w;
+
+ if (z == 0.0) {
+ x = 0.0;
+ } else {
+ y = 0.5 * fabs(z);
+ if (y >= (Z_MAX * 0.5)) {
+ x = 1.0;
+ } else if (y < 1.0) {
+ w = y * y;
+ x = ((((((((0.000124818987 * w
+ -0.001075204047) * w +0.005198775019) * w
+ -0.019198292004) * w +0.059054035642) * w
+ -0.151968751364) * w +0.319152932694) * w
+ -0.531923007300) * w +0.797884560593) * y * 2.0;
+ } else {
+ y -= 2.0;
+ x = (((((((((((((-0.000045255659 * y
+ +0.000152529290) * y -0.000019538132) * y
+ -0.000676904986) * y +0.001390604284) * y
+ -0.000794620820) * y -0.002034254874) * y
+ +0.006549791214) * y -0.010557625006) * y
+ +0.011630447319) * y -0.009279453341) * y
+ +0.005353579108) * y -0.002141268741) * y
+ +0.000535310849) * y +0.999936657524;
+ }
+ }
+ return (z > 0.0 ? ((x + 1.0) * 0.5) : ((1.0 - x) * 0.5));
+}
+
+/*
+ Module: chisq.c
+ Purpose: compute approximations to chisquare distribution probabilities
+ Contents: pochisq()
+ Uses: poz() in z.c (Algorithm 209)
+ Programmer: Gary Perlman
+ Organization: Wang Institute, Tyngsboro, MA 01879
+ Copyright: none
+ Tabstops: 4
+*/
+
+#define LOG_SQRT_PI 0.5723649429247000870717135 /* log (sqrt (pi)) */
+#define I_SQRT_PI 0.5641895835477562869480795 /* 1 / sqrt (pi) */
+#define BIGX 20.0 /* max value to represent exp (x) */
+#define ex(x) (((x) < -BIGX) ? 0.0 : exp(x))
+
+/*FUNCTION pochisq: probability of chi sqaure value */
+/*ALGORITHM Compute probability of chi square value.
+ Adapted from:
+ Hill, I. D. and Pike, M. C. Algorithm 299
+ Collected Algorithms for the CACM 1967 p. 243
+ Updated for rounding errors based on remark in
+ ACM TOMS June 1985, page 185
+*/
+
+double pochisq(
+ const double ax, /* obtained chi-square value */
+ const int df /* degrees of freedom */
+ )
+{
+ double x = ax;
+ double a, y, s;
+ double e, c, z;
+ int even; /* true if df is an even number */
+
+ if (x <= 0.0 || df < 1) {
+ return 1.0;
+ }
+
+ a = 0.5 * x;
+ even = (2 * (df / 2)) == df;
+ y = 0.0;
+ if (df > 1) {
+ y = ex(-a);
+ }
+ s = (even ? y : (2.0 * poz(-sqrt(x))));
+ if (df > 2) {
+ x = 0.5 * (df - 1.0);
+ z = (even ? 1.0 : 0.5);
+ if (a > BIGX) {
+ e = (even ? 0.0 : LOG_SQRT_PI);
+ c = log(a);
+ while (z <= x) {
+ e = log(z) + e;
+ s += ex(c * z - a - e);
+ z += 1.0;
+ }
+ return (s);
+ } else {
+ e = (even ? 1.0 : (I_SQRT_PI / sqrt(a)));
+ c = 0.0;
+ while (z <= x) {
+ e = e * (a / z);
+ c = c + e;
+ z += 1.0;
+ }
+ return (c * y + s);
+ }
+ } else {
+ return s;
+ }
+}