Microarchitecture and Microprogramming based on J. Kawash - 2014

Assignment 4: Microarchitecture and Microprogramming
based on J. Kawash - 2014
Background
Microarchitecture refers to the organization of a computer processor to implement its instruction set. Microprogramming
is a means to implement a state machine to control the microarchitecture. This assignment introduces you
to these concepts by experimenting with an architecture that implements an integer Java virtual machine (IJVM), a
simplified version of the Java virtual machine (JVM) than interprets Java Assembly (JAS) language.
Objectives
Your goal is to become familiar with an IJVM simulator by augmenting its instruction set and writing/modifying some
simple JAS code to test the augmented instruction set.
1 Add a new ISA instruction (2 points)
In this part, we will walk you through the steps to modify the microprogram. We will add a new JAS instruction INEG
that negates (in 2’s complement) the value at the top of the stack. INEG is an actual instruction in the JVM, but is
not included in our IJVM. (For a listing of JVM opcodes see http://docs.oracle.com/javase/specs/jvms/se7/html/jvms6.html).
Locate the file ijvm.conf, within the Mic-1 MMV files. Add to it the following line:
0x74 INEG \\ write an appropriate comment
We are using the opcode 0x74 since it is the actual opcode of INEG in JVM and it is not used by any other existing
instruction in IJVM.
Locate the file mic1ijvm.mal, which contains the Mic-1 microprogram. At the beginning of the file, there are few
labels defined, one for each starting address of the mircoinstrucions that interprets a given JAS instruction. Add to
these labels the following line:
.label ineg1 0x74
(Make sure the value (0x74) is the same as the one you defined in ijvm.conf.)
At the end of the file add the following microinstructions:
ineg1 H = TOS // read top of stack to H
ineg2 MAR = SP
ineg3 TOS = MDR = -H; wr; goto Main1 // negate TOS and write
// back to stack
Add appropriate comments to these microinstructions.
Run MMV from a folder that contains ijvm.conf. From MMV, open mic1ijvm.mal assemble it, and load it. If it
contains errors, correct them. (The code provided here has been tested and is error-free).
You have modified the microporgam so that it supports the new ISA (or JAS) instruction INEG. You will need it
for the next part.
2 Use the new instruction (4 points)
Write a JAS program that contains the method iabs(int x), which returns the absolute value of its argument, x.
Since IJVM does not have a native instruction to calculate the absolute value of an integer, you have to code it
using the existing IJVM instructions, in addition to the new INEG. The algorithm is straightforward: if the value at
the top of the stack is positive, then return it as is; otherwise negate it, using INEG, and return it.
3 Add some IO for testing (4 points)
In the file add.jas contained in the examples folder of Mic-1 MMV, there are I/O methods to read and print numbers.
You may use these methods for testing; however, they do not work with negative numbers. Write your own getnum()
and print() methods that work with negative numbers.
Team Work
You may work individually, or with a partner, but no larger groups.
Programs that do not compile cannot receive more than 3 points. Programs that compile, but do not implement any
of the functionality described above can receive a maximum of 5 points.
Submit a .tar.gz file of your entire project directory (including source code, make file, build objects, kernel.img,
etc) to your TA via the appropriate dropbox on Desire2Learn. If you are working with group members in different
tutorial sections, choose just one TA to submit to.