CSC$221$ Project $05$: MS$-$DOS Date$-$Time Formatter $($Unpacking$)$

Objective: Use the provided starter code to:

$1.$ Unpack a $32-$bit MS$-$DOS Date$-$Time format stored in the EDX register.

$2.$ Extract and display the year, month, day, hour, minute, and second fields.

Starter Code:

The provided starter code:

$1.$ Gets the current date and time from the system.

$2.$ Packs the year, month, day, hour, minute, and second into the $32-$bit EDX register, formatted

as follows:

Bit Index Field Bits Range

$02$ Second $3030$ take $65$ bits second shift $3($divide by $8)$ to get $3$ bits

$38$ Minute $6059$

$913$ Hour $5023$

$14-15$ Empty

$1620$ Day $5131$

$2124$ Month $4112$

$2531$ Year Offset $70127(19802107)$

The year is stored as an offset from $1980($e$.$g$.,1999$ is stored as $19).$

Your Task:

$1.$ Unpack the $32-$bit value in EDX:

o Extract each field $($year$,$ month, day, hour, minute, second$)$ using bitwise operations

$($AND$,$ SHR$,$ etc.$).$

o Restore the full year by adding $1980$ to the unpacked value.

o Restore the seconds by multiplying the $3-$bit value by $8($SHL al$,3).$

$2.$ Display the unpacked values:

o Print each field in the format:

Year: YYYY$,$ Month: MM$,$ Day: DD$,$ Hour: HH$,$ Minute: MM$,$ Second: SS$.$

Steps to Complete the Project

$1.$ Unpacking Logic $($Procedure: unpack$)$:

Write a procedure called unpack that:

$1.$ Receives the packed $32-$bit value in EDX.

$2.$ Using the procedure sub given extracts and print the fields for time using:

o Shift right by $16($remove time$)$

o Days $($bits $04)$: mask off month and year with AND

o Months $($bits $58)$: Shift right by $5$ and mask with AND $01111$b

o Years $($bits $915)$: Shift right by $9$ and then add $1980.$

$3.$ Using the procedure sub given extracts and print the fields for time using:

o Seconds $($bits $02)$: And $0111$b and shift left by $3($multiple $8).$

o Minutes $($bits$38)$: Shift right by $3$ and mask with AND $0111111$b$.$

o Hours $($bits $913)$: Shift right by $9$ and mask with AND $0111111111$b$.$

Note: these instructions are general guidelines, there could be minor errors

Program Structure

$1.$ Call the starter code to populate the EDX register with the packed $32-$bit date$-$time value.

$2.$ Call the two Unpack and Display procedures.

Program

$$ Input: Unpacked fields from registers.

$$ Output: Formatted date$-$time string to the console.

Requirements:

$$ Submitted program must build, code that does not build will not be graded

$$ Correctly format code, special care given to indentations and spacing, goal is for readability

$$ Comment all code, have comment header with description, project number, author$$s name

and date of last modification Procedures $($excluding main$)$ must have complete

Descriptions, Receives, Returns, Requires

$$ Use the course convention for naming the submitted file

Example User Interaction

The current date is $($YYYY:MM:DD$)$: $2024$:$11$:$23$

The current time is $($HH:MM:SS$)$: $12$:$16$:$7$

YYYY YYYM MMMD DDDD $00$HH HHHM MMMM MSSS

edx $=01011001011101110001100010000000$b

The current date is $($YYYY:MM:DD$)$: $2024$:$11$:$23$

The current time is $($HH:MM:SS$)$: $12$:$16$:$0$

Deliverables

$1.$ A well$-$documented MASM assembly program including:

o File name, project description, author, and last modified date.

o Comments for each block of code to explain its purpose.

$2.$ The program must:

o Use the starter code to pack the value into EDX.

o Include your unpack and display procedures.

o Use Irvine$32$ library procedures for I$/$O operations.

o Use only the procedures we discussed in class

o Keep the existing structure, dont change anything but the two Unpack and Display

procedures.

Helpful Hints

$$ Use masking $($AND$)$ and shifting $($SHR$)$ to extract specific bits for each field.

$$ Test your unpacking logic thoroughly by comparing output with the original values.

$$ Use the provided WriteBin function $($or mshow macro$)$ to see the packed binary value or even

better use the debugger on visual studio.