Computer Organization Lab 05

CSCI 2500 — Computer Organization
Lab 05 (document version 1.2)
ˆ This lab is due by the end of your lab session on Wednesday, October 2, 2019.
ˆ This lab is to be completed individually. Do not share your code with anyone else.
ˆ You must show your code and your solutions to a TA or mentor to receive credit for each
checkpoint.
ˆ Labs are available on Mondays before your lab sessions. Plan to start each lab early and
ask questions during office hours, in the discussion forum on Submitty, and during your lab
session.
1. Checkpoint 1: For the first checkpoint, write MIPS code to determine whether a given
unsigned integer in register $a0 is even or odd. Implement this as a procedure (i.e., function)
labeled isodd. This procedure must display either “EVEN” or “ODD” via the appropriate
syscall, then return 0 if even or 1 if odd. Note that to return a value to the caller, use register
$v0, then view the contents of this register via the print_all_regs or print command in
SPIM.
2. Checkpoint 2: For the second checkpoint, write a MIPS procedure to extract and display
each of the four individual bytes of a given unsigned 32-bit value in register $a0. You must
implement two working versions to earn full credit for this checkpoint; in the first version,
you are only allowed to use sll and srl instructions, then in the second version, you must
minimize the number of sll and srl instructions that you use by first using and, or, and/or
nor instructions.
As an example, if register $a0 contains unsigned integer 0x4a889cf1 (i.e., 1,250,467,057 in
base 10), your procedure should output the following:
byte #1: 74
byte #2: 136
byte #3: 156
byte #4: 241
Test your procedure by calling it from main with a variety of input values in $a0. Further,
you are encouraged to write reusable procedures to make your code easier to follow and more
maintainable.
3. Checkpoint 3: For the third checkpoint, write a MIPS procedure labeled numodds that
counts the number of odd integers that appear in a given list of integers. Use register $a0 to
specify the base address of the array and register $a1 to specify how many 32-bit unsigned
integers are in the array. Finally, return the number of odd integers in register $v0.
Reuse the procedure from the first checkpoint to implement your solution to this checkpoint.
And to test your code, use the .word directive to store a sequence of values in memory, e.g.:
.data
list: .word 12,100,101,5,123456789,18
Use print_all_regs or print to see the result of your function call (i.e., by looking at the
contents of register $v0).