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#!/bin/sh
#
# check-zzuf-r-ratio - zzuf RNG statistic tests
#
# Copyright © 2002—2015 Sam Hocevar <sam@hocevar.net>
#
# This program is free software. It comes without any warranty, to
# the extent permitted by applicable law. You can redistribute it
# and/or modify it under the terms of the Do What the Fuck You Want
# to Public License, Version 2, as published by the WTFPL Task Force.
# See http://www.wtfpl.net/ for more details.
#
. "$(dirname "$0")/functions.inc"
checkflip()
{
r=$1
expect=$2
mib=20
try=3
s2=$seed
new_test "$mib MiB of zeroes, ratio $r"
echo " expecting $expect"
checkflip_internal $1 $2 $mib $try $s2
}
checkflip_internal()
{
r=$1
expect=$2
mib=$3
try=$4
s2=$5
rmax=-1
rmin=-1
rtot=0
printf " got"
for x in 0 1 2 3 4; do
ret=`dd if=/dev/zero bs=1048576 count=$mib 2>/dev/null | $ZZUF -s $s2 -r $r | "$ZZERO"`
if [ "$rmax" = -1 -o "$ret" -gt "$rmax" ]; then rmax=$ret; fi
if [ "$rmin" = -1 -o "$ret" -lt "$rmin" ]; then rmin=$ret; fi
rtot=`expr $rtot + $ret || true`
printf " $ret"
s2=`expr $s2 + 1`
done
echo ""
rmean=`expr '(' $rtot + 2 ')' / 5 || true`
delta=`expr $rmean - $expect || true`
printf " min/avg/max $rmin/$rmean/$rmax .........."
if [ "$delta" -gt -5 -a "$delta" -lt 5 ]; then
pass_test " ok"
elif [ $(($rmean * 8)) -lt $(($expect * 7)) \
-o $(($rmean * 7)) -gt $(($expect * 8)) ]; then
if [ $try -gt 0 ]; then
# Hack: if we failed with that seed, just try another one.
# Kinda defeats the purpose of the test, but well, that's
# how randomness works, you cannot win each time.
echo " trying again"
checkflip_internal $1 $2 $3 $(($3 - 1)) "$3$s2"
else
fail_test " FAILED"
fi
else
pass_test " ok"
fi
}
start_test "zzuf -r test"
# if X flips are performed on N bits set to 0, the average number of bits
# set to 1 is: N / 2 * (1 - pow(1 - 2 / N, X)
checkflip 0.000000001 0
checkflip 0.00000001 1
checkflip 0.0000001 16
checkflip 0.000001 167
checkflip 0.00001 1677
checkflip 0.0001 16775
checkflip 0.001 167604
checkflip 0.01 1661055
checkflip 0.1 15205967
stop_test
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