Question

Write an assembly language program that repeatedly prompts the user to enter signed decimal integer numbers. The program should be run from the command prompt, output a text prompt to the screen, and then wait for the user to type in a number followed by the Enter key. (The legitimate range of user input values is any signed integer that can be represented in 32 bits.) After each number is entered, the program should determine and display the following information about the number: whether it is positive or negative; whether or not it is evenly divisible by 16; and whether or not it can be represented in 16 bits (in other words, is it in the range -32768 x +32767). For example, if the user entered the number +5, the output generated by the program should look similar to this:
+5 is a positive number.
+5 is not evenly divisible by 16.
+5 can be represented in 16 bits.
On the other hand, if the user entered -32816, the output would look like this:
-32816 is a negative number.
-32816 is evenly divisible by 16.
-32816 cannot be represented in 16 bits.
After determining and displaying the above information, the program should prompt the user to enter another number. This process should continue until the user enters the value 0 (which is neither positive nor negative). At that point, execution should terminate and return to the command prompt.
Assemble, link, and test your program. Make sure to test it for each of the eight possible input cases (permutations of positive vs. negative, divisible by 16 vs. not divisible by 16, and fits in 16 bits vs. does not fit in 16 bits), as well as the ninth possibility (the special case of 0, which exits the program). When you are sure it is working, run it from the command prompt and capture a screen shot(s) of a test run that illustrates all nine possibilities and the corresponding outputs.

Answer 1

Required Assembly code is given below:

.LC0:

        .string "%d"

.LC1:

        .string "%d is a positive number.\n"

.LC2:

        .string "%d is a negative number.\n"

.LC3:

        .string "%d is evenly divisible by 16.\n"

.LC4:

        .string "%d is not evenly divisible by 16.\n"

.LC5:

        .string "%d can be represented in 16 bits.\n"

.LC6:

        .string "%d cannot be represented in 16 bits.\n"

main:

        push    rbp

        mov     rbp, rsp

        sub     rsp, 16

.L8:

        lea     rax, [rbp-4]

        mov     rsi, rax

        mov     edi, OFFSET FLAT:.LC0

        mov     eax, 0

        call    __isoc99_scanf

        mov     eax, DWORD PTR [rbp-4]

        test    eax, eax

        jle     .L2

        mov     eax, DWORD PTR [rbp-4]

        mov     esi, eax

        mov     edi, OFFSET FLAT:.LC1

        mov     eax, 0

        call    printf

.L2:

        mov     eax, DWORD PTR [rbp-4]

        test    eax, eax

        jns     .L3

        mov     eax, DWORD PTR [rbp-4]

        mov     esi, eax

        mov     edi, OFFSET FLAT:.LC2

        mov     eax, 0

        call    printf

.L3:

        mov     eax, DWORD PTR [rbp-4]

        and     eax, 15

        test    eax, eax

        jne     .L4

        mov     eax, DWORD PTR [rbp-4]

        test    eax, eax

        je      .L4

        mov     eax, DWORD PTR [rbp-4]

        mov     esi, eax

        mov     edi, OFFSET FLAT:.LC3

        mov     eax, 0

        call    printf

.L4:

        mov     eax, DWORD PTR [rbp-4]

        and     eax, 15

        test    eax, eax

        je      .L5

        mov     eax, DWORD PTR [rbp-4]

        test    eax, eax

        je      .L5

        mov     eax, DWORD PTR [rbp-4]

        mov     esi, eax

        mov     edi, OFFSET FLAT:.LC4

        mov     eax, 0

        call    printf

.L5:

        mov     eax, DWORD PTR [rbp-4]

        cmp     eax, -32768

        jl      .L6

        mov     eax, DWORD PTR [rbp-4]

        cmp     eax, 32767

        jg      .L6

        mov     eax, DWORD PTR [rbp-4]

        test    eax, eax

        je      .L6

        mov     eax, DWORD PTR [rbp-4]

        mov     esi, eax

        mov     edi, OFFSET FLAT:.LC5

        mov     eax, 0

        call    printf

.L6:

        mov     eax, DWORD PTR [rbp-4]

        cmp     eax, -32768

        jge     .L7

        mov     eax, DWORD PTR [rbp-4]

        cmp     eax, 32767

        jle     .L7

        mov     eax, DWORD PTR [rbp-4]

        test    eax, eax

        je      .L7

        mov     eax, DWORD PTR [rbp-4]

        mov     esi, eax

        mov     edi, OFFSET FLAT:.LC6

        mov     eax, 0

        call    printf

.L7:

        mov     eax, DWORD PTR [rbp-4]

        test    eax, eax

        jne     .L8

        mov     eax, 0

        leave

        ret

Screenshot of above code output is given below:

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