Shell Programming and Scripting

#! /usr/bin/ksh



#
# Set up a bc coprocess

bc |&
print -p ibase=16

#########################################################################
####  Tigershark ---   a portable and powerful RNG
#
#  This is a Recusion With Carry generator.  It has an output modulus
#  of 32768 and a period of 9,194,221,792,641,269,759.

typeset -u Entropy ZeroEntropy
ZeroEntropy="0000000000000000000000000000000000000000"
Entropy=$ZeroEntropy

typeset -i10 X3 X2 X1 X0 Carry Sum
Period=9194221792649674751
Carry=0
Sum=0
Ttigershark=0
Stigershark=0
# Sum = (Word) the accumulator
# Carry = carry
# Ttigershark = Total calls
# Stigershark = Total times started


#
#  The function is now mostly for reference.  The 7 lines inside the
#  the function are used in most places where the function was once called.
#  This improves speed.

function tigershark
{
    ((Sum=15*X3 + 31111*X2 + 15*X1 + 1064*X0 + Carry ))
    ((Carry=Sum >> 15))
    ((X0=Sum & 16#7FFF ))
        X3=$X2
        X2=$X1
        X1=$X0
        ((Ttigershark=Ttigershark+1))
        return 0
}

#
#  weak_start_tigershark --- This is used when we can't get Entropy

function weak_start_tigershark
{
        typeset -i  i final duration
        ((final=SECONDS+2))

        while((SECONDS < final)) ; do
                i=$RANDOM
        done

        ((Carry=0))
        ((X0=$$))
        ((X1=RANDOM))
        ((X2=RANDOM))
        ((X3=RANDOM))
        Sum=0
        ((Stigershark=Stigershark+1))
        return 0
}


typeset -i16 hex
typeset -u -R2 dhex2
typeset -u -R4 dhex4

weak_start_tigershark
i=0
while ((i<100)) ; do
        tigershark
        ((hex=X0))
        dhex2=0000${hex#16#}
        cum=$dhex2
        tigershark
        ((hex=X0))
        dhex2=0000${hex#16#}
        cum=${dhex2}${cum}

        tigershark
        ((hex=X0))
        dhex4=0000${hex#16#}
        cum=${dhex4}${cum}
        print -p $cum
        read -p result
        echo $result
        ((i=i+1))
done
exit 0