Question

Run the following RISC-V codes separately and explain what each code does and how you interpret the register results:

Code 1.

addi x3, x3, 1

slli x3, x3, 62

addi x4, x4, 7

mul x5, x4, x3

mulh x6, x4, x3

Code 2.

addi x3, x3, 1
slli x3, x3, 63

addi x4, x4, 1

mul x5, x4, x3

mulhsu x6, x4, x3

Code 3.

addi x3, x3, 1
slli x3, x3, 63

addi x4, x4, 1

mul x5, x4, x3

mulhsu x6, x3, x4

Code 4.

addi x7, x7, 45

addi x4, x4, 3

div x5, x7, x4

div x6, x4, x7

Code 5.

addi x7, x7, -46

addi x4, x4, 3

div x5, x7, x4

rem x8, x7, x4

Code 6.

addi x7, x7, -46

addi x4, x4, 3

divu x5, x7, x4

Answer 1

Code 1

• The contents of x3 is added with 1 and the result is placed in x3 //x3=x3+1
• Shifting left by immediate and store in X3   // x3=x3<<62
• The contents of x4 is added with 7 and the result is placed in x4 //x4=x4+7
• The contents of x4 is multiplied by the contents of x3 and the result is placed in x5 // x5=x4*x3
• The contents of x4 is multiplied by the contents of x3 . The result is stored in x6. Also x6 will be having the most significat half. The operands x4,x3 and the results x6 will be of unsigned values// x6 = HighBits(x4*x3)

Code 2

• The contents of x3 is added with 1 and the result is placed in x3 //x3=x3+1
• Shifting left by immediate and store in X3   // x3=x3<<63

• The contents of x4 is added with 1 and the result is placed in x4 //x4=x4+1
• The contents of x4 is multiplied by the contents of x3 and the result is placed in x5 // x5=x4*x3
• The contents of x4 is multiplied by the contents of x3 . The result is stored in x6. Also x6 will be having the most significat half. Of x4 and x3, one will be signed and other will be unsigned and the result will be signed value // x6 = HighBits(x4*x3)

Code 3

• The contents of x3 is added with 1 and the result is placed in x3 //x3=x3+1
• Shifting left by immediate and store in X3   // x3=x3<<63
• The contents of x4 is added with 1 and the result is placed in x4 //x4=x4+1
• The contents of x4 is multiplied by the contents of x3 and the result is placed in x5 // x5=x4*x3
• The contents of x3 is multiplied by the contents of x4 . The result is stored in x6. Also x6 will be having the most significat half. Of x3 and x4, one will be signed and other will be unsigned and the result will be signed value // x6 = HighBits(x3*x4)

Code 4

• The contents of x7 is added with 45 and the result is placed in x7 //x7=x7+45

• The contents of x4 is added with 3 and the result is placed in x4 //x4=x4+3
• The contents of x7 is divided by the contents of x4 and the quotient is placed in x5. Both x7,x4 and the result are signed values.// x5= x7 DIV x4
• The contents of x4 is divided by the contents of x7 and the quotient is placed in x6. Both x4 ,x7 and the result are signed values.// x6= x4 DIV x7

Code 5.

• The contents of x7 is subtracted with 46 and the result is placed in x7 //x7=x7- 46
• The contents of x4 is added with 3 and the result is placed in x4 //x4=x4+3
• The contents of x7 is divided by the contents of x4 and the quotient is placed in x5. Both x7,x4 and the result are signed values.// x5= x7 DIV x4
• The contents of x7 is divided by the contents of x4 and the remainder is placed in x8. Both x7,x4 and the result are signed values.// x8= x7 REM x4

Code 6

• The contents of x7 is subtracted with 46 and the result is placed in x7 //x7=x7- 46
• The contents of x4 is added with 3 and the result is placed in x4 //x4=x4+3

• The contents of x7 is divided by the contents of x4 and the quotient is placed in x5. Both x7,x4 and the result are unsigned values.// x5= x7 DIV x4