Project 1 MIPS Assembly Language Disassembler

ECE 3056
Architecture, Concurrency and Energy in
Computation
Project 1
MIPS Assembly Language Disassembler
In this assignment, you will implement a simple disassembler program using MIPS assembly
language for the Mini-MIPS ISA defined below. You will use the MIPS functional simulator
for validating the functionality of your MIPS disassembler program. You can find useful information on SPIM here. Your program should disassemble only the six instructions defined
in the mini-MIPS ISA from the binary words provided. All other words not belonging to
any of the six instructions should print out “unsupported opcode !!” First, download the projskel.s skeleton file which is attached to this assignment. This skeleton file contains 14 instructions defined after the label “binary_code” in hexadecimal format. Each instruction is
encoded by each .word using Little Endian byte-order. Your MIPS program should read
one .word at a time, decode the .word binary to determine the instruction, and then print
out each instruction on the Console window. Note that some instructions in the skeleton
program are not defined by the Mini-MIPS ISA. During disassembly, your program should
print out “Unsupported opcode !!“ on the console window when encountering such instructions
. Be sure to note that the Offset field encodes a signed number, be cautious when you print
them out. For jump target, assume that the four msbs of the PC are 0000.
Mini-MIPS ISA (contains only 6 instructions, you can find the same format of these
6 instructions in Appendix A of H&P)
Summer 2015
Printout example on the SPIM console window:
Hint. In the skeleton file, a few ASCII (.asciiz) symbols and instruction mnemonics (e.g. lw)
are defined. You can use them to print out some of the needed instruction symbols in the
Console window. There are many repetitive operations to carry out in your program (e.g.
print dollar sign ($) before print the register number). In order to reduce the code size, you
are encouraged to use procedure/function call, e.g. jal instruction for call and its corresponding jr $31 for return in MIPS, to handle these repetitive operations. If you are careful
in how you allocate your registers, you will not need to use the stack to store the procedure‘s local variables etc. An example function might extract an unsigned 5-bit number from
a register, given a bit offset into the register.
SPIM Simulator Warmup. The SPIM simulator will be used for executing your MIPS program. For those who use PCSpim on Windows, uncheck the “load trap file” under
Simulator→Settings since our skeleton file already contains _start initialization code. If
you’ve never used any editor such as vi, emacs, MS visual IDE to write programs before, a
free syntax-coloring editor with MIPS syntax coloring files is available at www.crimsoneditor.com.
Signoff. You must go to the lab hours held by TA for having your assignment checked off
before the due time (last scheduled hours) or the first hours scheduled after the due date.
In either case, the code must be submitted on T-square on time (Friday 5/29 before
11:55pm). Also, please turn in your code on the assignment page. Contact Taimour (our TA)
for alternative appointments for check-off. A rubric defining how points are allocated is attached. Also note that, Taimour might use a different input set to perform further tests.
lw $4 24($10)
addi $5 $6 -7
unsupported opcode !
and $2 $3 $4
unsupported opcode !
jal 120000
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