CSCI $202$ Computer Organization II

MIPS Programming Project

Due February $15$th$,12$:$40$PM ET

Description:

Assume your Howard ID as a decimal integer is X$.$ Let N $=26+($X $\%11)$ where $\%$ is the modulo

operation, and M $=$ N $10.$

You will write a MIPS program that reads a string of up to $1000$ characters $($excluding the trailing

carriage return and null character$)$ from user input.

$$ With single slash $(/)$ as the delimiter, split the input string into multiple substrings $($with the

slash removed$).$ If there is no slash in the input, the whole input string is considered a

substring referred to below.

$$ For each substring,

o Pick the characters from $\text{'}0\text{'}$ to $\text{'}9\text{'}$ and from $\text{'}$a$\text{'}$ to $\backslash$beta and from $\text{'}$A$\text{'}$ to $\backslash$Delta $.\backslash$beta stands for the Mth lower case letter and $\backslash$Delta stands for the M$-$th upper case letter in the English alphabet,

where M is as defined at the beginning of the description. Consider each such character

as a base$-$N digit and calculate the sum. The sum is $"-"$ if there are no such characters.

In a base$-$N number, both $\text{'}$a$\text{'}$ and $\text{'}$A$\text{'}$ correspond to the decimal integer of $10,$ both $\text{'}$b$\text{'}$

and $\text{'}$B$\text{'}$ to $11,$ and so on$,$ and both $\backslash$beta and $\backslash$Delta correspond to N $1.$

o Output the calculated sum.

$$ If there are multiple substrings, the output for the substrings should be separated by two

spaces with a single slash in between, for example, $"2/3/4".$

$$ The program must exit after processing one single user input.

$$ The processing of the whole input string must be done in a subprogram labelled as

process$\_$whole$\_$string. The main program must call process$\_$whole$\_$string and pass the string

address into it via the register $a$0.$ The subprogram parses the string and prints the output

as described above. No return value is necessary from the subprogram.

$$ When processing each substring, process$\_$whole$\_$string must call another subprogram

labelled as process$\_$substring, where the substring address is passed into process$\_$substring

via the stack, and the sum of the substring isreturned to Subprogram A via the register $v$0.$

Sample test cases $($assuming the Howard ID is $12345678)$:

$12345678\%11=4,$ therefore the base is $26+4=30,\backslash$beta is $\text{'}$t$\text{'}$ and $\backslash$Delta is $\text{'}$T$\text{'}.$

$$ Input: C

Output: $12$

$$ Input: $0/1/2/$A$/$b$/$T$/$t$/$Z$/?$

Output: $0/1/2/10/11/29/29/-/-$

$$ Input: a$0/123/0$Ab$9$

Output: $10/6/30$

$$ Input: $10/$ xyz$!/2\mathrm{.}3\mathrm{.}4/$ @$!$A t$ $//$

Output: $1/-/9/39/-/-$

Requirements:

$$ The program must be able to run correctly under QtSpim.

$$ The program must be named as mips.s$.$

$$ The output must have the exact format as specified above. No other messages or promptsshould

be printed except the numbers and the error messages.

$$ The subprograms must be labelled properly as required.

$$ All development must be done with Github. A brand new Github repo dedicated to this project

must be used.

$$ Specifically, there MUST BE ONE COMMIT for EVERY $($or fewer for the last$)$ five lines of new or

modified MIPS code $($excluding empty lines, and lines with only comment$/$directives$/$labels$).$ More

frequent commit is fine. With each commit, the commit message must explain the purpose of the

added$/$changed code. Commits must be made while the program is being developed. Commits

done afterwards are NOT ACCETPABLE.

$$ Submissions not fully meeting the above requirements will lose significant portion $(>=70\%)$ of

the credits.

$$ Syntax error or program terminating abnormally without output will result in zero credits. If the

program freezes during execution, a large number of points will be deducted. Therefore, make

sure to test your program thoroughly before submission.