CPSC 355: Computing Machinery I Assignment 02


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Integer Multiplication using Add and Shift Operations

Create an ARMv8 assembly language program that implements the following integer
multiplication program:
#define FALSE 0
#define TRUE 1
int main()
int multiplier, multiplicand, product, i, negative;
long int result, temp1, temp2;
// Initialize variables
multiplicand = -16843010;
multiplier = 70;
product = 0;
// Print out initial values of variables
printf(“multiplier = 0x%08x (%d) multiplicand = 0x%08x (%d)\n\n”,
multiplier, multiplier, multiplicand, multiplicand);
// Determine if multiplier is negative
negative = multiplier < 0 ? TRUE : FALSE;
// Do repeated add and shift
for (i = 0; i < 32; i++) { if (multiplier & 0x1) { product = product + multiplicand; } // Arithmetic shift right the combined product and multiplier multiplier = multiplier >> 1;
if (product & 0x1) {
multiplier = multiplier | 0x80000000;
} else {
multiplier = multiplier & 0x7FFFFFFF;
product = product >> 1;
// Adjust product register if multiplier is negative
if (negative) {
product = product – multiplicand;
// Print out product and multiplier
printf(“product = 0x%08x multiplier = 0x%08x\n”,
product, multiplier);
// Combine product and multiplier together
temp1 = (long int)product & 0xFFFFFFFF;
temp1 = temp1 << 32;
temp2 = (long int)multiplier & 0xFFFFFFFF;
result = temp1 + temp2;
// Print out 64-bit result
printf(“64-bit result = 0x%016lx (%ld)\n”, result, result);
return 0;

Be sure to use 32-bit registers for variables declared using int, and 64-bit registers for variables
declared using long int. Use m4 macros to name the registers to make your code more readable.
Name the program assign2a.asm. Optimize your code so that it uses as few instructions as

Also run the program in gdb, displaying the contents of key registers as the program executes;
you should show that the algorithm is working as expected. Capture the gdb session using the
Unix command script and name the output file script.txt.

Create a second version of the program (called assign2b.asm) that uses 522133279 for the
multiplicand, and 200 for the multiplier. Also create a third version of the program (called
assign2c.asm) that uses -252645136 for the multiplicand, and -256 for the multiplier.

Other Requirements

Make sure your code is properly formatted into columns, is readable and fully documented, and
includes identifying information at the top of each file. You must comment each line of assembly
code. Your code should also be well designed: make sure it is well organized, clear, and concise.

New Skills Needed for this Assignment:
• Use of bitwise logical and shift operations.
• Use of branching and condition code tests.
• Understanding of hexadecimal and binary numbers.

Submit the following:
Your assembly source code files for the 3 programs, and your script output file. Use the Assignment 2
Dropbox Folder in D2L to submit electronically. The TA will assemble and run your programs to test them.
Be sure to name your programs and script file as described above.
Marking Criteria
Correct calculation of product 4 ______
Use of bit masking 6 ______
Use of shift instructions 3 ______
Display to screen 3 ______
Optimization 3 ______
Script showing gdb session 3 ______
Complete documentation and commenting 4 ______
Design quality 2 ______
Version 2 2 ______
Version 3 2 ______
Total 32 ______