#!/bin/sh

set -e

checkflip()
{
    r=$1
    expect=$2
    s2=$seed
    mib=20
    echo "*** $mib MiB of zeroes, ratio $r ***"
    rmax=-1
    rmin=-1
    rtot=0
    for x in 0 1 2 3 4; do
        ret=`dd if=/dev/zero bs=1048576 count=$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`
        echo " try $x .......... $ret"
        s2=`expr $s2 + 1`
    done
    rmean=`expr '(' $rtot + 2 ')' / 5 || true`
    delta=`expr $rmean - $expect || true`
    if [ "$delta" -gt -5 -a "$delta" -lt 5 ]; then
        result="ok"
    elif [ $(($rmean * 8)) -lt $(($expect * 7)) \
               -o $(($rmean * 7)) -gt $(($expect * 8)) ]; then
        result="FAILED"
        FAILED=$(($FAILED + 1))
    else
        result="ok"
    fi
    TESTED=$(($TESTED + 1))
    echo " expected $expect min/avg/max $rmin/$rmean/$rmax .......... $result"
}

DIR="$(dirname "$0")"
ZZUF="$DIR/../src/zzuf"
ZZERO="$DIR/zzero"
if [ ! -f "$ZZERO" ]; then
  echo "error: test/zzero is missing"
  exit 1
fi
FAILED=0
TESTED=0

if [ -z "$1" ]; then
  seed=$(date | $ZZUF -m 2>/dev/null | cut -f2 -d' ' | tr -d abcdef | cut -b1-8)
else
  seed="$1"
fi

echo "*** running zzuf RNG test suite with seed $seed ***"

# 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

if [ "$FAILED" != 0 ]; then
    echo "*** $FAILED tests failed out of $TESTED ***"
    exit 1
fi
echo "*** all $TESTED tests OK ***"

exit 0