Programming Homework Help

Week08 bitRotate.hla and misc. Exercises: 50 points +.

Someone complained that there wasn't enough practice, and I wholeheartedly
agree...anybody who has to put up with the instructor's voice should get a 
break, and often. 

So let's "work" the information in week08.txt.
Go to your asst3 directory, create, assemble and run hello.S

Now, everybody knows we can read the command line parms, and
how to use the "waterpump".  If you just copy Caesarshift.hla
here and rename it as bitRotate.hla, you can probably create
a crypto tool in 15 minutes which rotates the bits in each byte
the number of times in the command line parm.  Think about it.
Remind me to shut up and let you work on this TODAY.  Like I say,
it builds on what we already know, and adds the shift/rotate
tools in the CPU.  It probably doesn't matter to our command
(Eighth Army) whether we rotate right or left, since by 
using the right number on the command line, one can mimic the 
other's output.

REMEMBER: YOUR OUTPUT WON'T BE READABLE.  Rotating bits often 
converts a byte of text from readable text to low-order control 
characters, so run your program this way:

bitRotate 3 < filea.in > filea.out

Then, to see what a mess we've made, look inside the output
file this way:

hexdump < filea.out | less

(Hey, we're flying with the big birds now....)

To confirm your logic, you should be able to do this:

bitRotate 4 < textfile | bitRotate 4

What you get should be what you input.  Check it.