x86 Arithmetic Instructions Quiz

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Questions and Answers

What distinguishes an arithmetic right shift from a logical right shift?

The arithmetic right shift cannot be used for signed integers.

The logical right shift is faster than the arithmetic right shift.

The logical right shift shifts all bits the same way, while the arithmetic does not.

The arithmetic right shift replicates the sign bit while the logical does not. (correct)

In which type of shift operation is the sign bit preserved?

Logical left shift

Logical right shift

Arithmetic right shift (correct)

Arithmetic left shift

What is the result of a logical left shift operation on the binary number 10100110 by 3 bits?

00010100

10110000

11110100

00110000 (correct)

What does the operation defined as SAL do?

Shifts the source operand to the left and clears empty positions. Signup and view all the answers

How are bits treated in a cycling shift (rotate) operation?

Bits are replicated from the end to the start without omission. Signup and view all the answers

Which operation can speed up certain arithmetic operations?

Both arithmetic and logical shifts Signup and view all the answers

What happens during an arithmetic left shift?

The bits shift left and empty positions are filled with zeros. Signup and view all the answers

What is the output of a right rotate operation on the binary number 10100110 by 3 bits?

11010100 Signup and view all the answers

What does the DEC instruction do?

Subtracts 1 from the destination operand Signup and view all the answers

Which operation updates the status flags without altering the operands?

CMP Signup and view all the answers

What is the effect of the NEG instruction on the operand?

It replaces the value of the operand with its two's complement Signup and view all the answers

In the context of arithmetic operations, what does the INC instruction perform?

Adds 1 to the operand Signup and view all the answers

Which flag is NOT affected by the ADD instruction?

V flag Signup and view all the answers

What does the CMP instruction compare?

Two operands by subtracting the second from the first Signup and view all the answers

Which operation is performed last in the sequence provided for arithmetic operations?

Increment Signup and view all the answers

Which of the following operations does NOT use decimal mode when the D flag is set?

ADD Dest, Source Signup and view all the answers

What is the purpose of the NOT instruction?

It inverts each bit of the operand. Signup and view all the answers

Which operation is performed by the AND instruction?

Performs a bitwise AND operation. Signup and view all the answers

In which registers can unsigned division results be stored?

AX, DX, EDX Signup and view all the answers

What is the characteristic of logic instructions in terms of flags?

All logic instructions affect flag bits except for the NOT instruction. Signup and view all the answers

How does the INC instruction function?

It adds 1 to the destination operand. Signup and view all the answers

Which multiplication instruction performs an unsigned integer multiplication?

MUL Signup and view all the answers

What is the function of the DIV instruction?

It performs unsigned value division. Signup and view all the answers

Which of the following instructions preserves the state of the CF flag?

INC Signup and view all the answers

What does the OR operation do with its operands?

It performs a bitwise OR operation. Signup and view all the answers

What flags does the XOR operation affect?

The S, Z, and P flags. Signup and view all the answers

In a logical shift left operation, what happens to the bit on the leftmost end?

It is shifted out and lost. Signup and view all the answers

How does the ROL instruction manipulate bits?

It rotates bits to the left, storing the last bit shifted out in the CF flag. Signup and view all the answers

What does the RCR instruction do?

It rotates bits to the right and includes the CF flag with wraparound. Signup and view all the answers

What happens when the TEST instruction is executed?

It performs a bitwise AND operation on two operands and sets the S, Z, and P status flags. Signup and view all the answers

What does the ROL instruction leave unchanged?

The operands Signup and view all the answers

Which operation treats the CF flag as a 1-bit extension during the shifting process?

RCL (Rotate Left through Carry) Signup and view all the answers

Study Notes

Arithmetic Operations

Basic Arithmetic Operations: Add, subtract, multiply, and divide.
Arithmetic instructions may involve data transfers to position operands for ALU input and deliver ALU output.

Common x86 Arithmetic Instructions

ADD Dest, Source: Adds the destination and source operands, storing the result in the destination operand.
SUB Dest, Source: Subtracts the source from the destination and stores the result in the destination operand.
MUL Op: Performs an unsigned integer multiplication of the operand by the AL, AX, and EAX registers.
IMUL Op: Performs a signed integer multiplication.
DIV Op: Divides unsigned values in the AX, DX:AX, EDX:EAX, or RDX:RAX registers (dividend) by the source operand (divisor).
IDIV Op: Divides signed integers.
DEC Op: Subtracts 1 from the destination operand, preserving the state of the CF flag.
NEG Op: Replaces the value of the operand with (0 – operand), using two's complement representation.
CMP Op1, Op2: Compares two operands by subtracting the second operand from the first.

CMP Instruction Details

Determines if the destination operand is greater than, equal to, or less than the source operand.
Updates status flags (C, P, A, Z, S, O).
It does not alter either of the operands.
It can be followed by a conditional jump instruction or a set condition instruction.
It does not use decimal mode if the D flag is set.
It does not affect the value of the V flag.
Supports all addressing modes.

Logic and Shift Operations

Logic and shift operations are referred to as bit manipulation instructions.
They operate on a bit-by-bit basis.
Logic instructions can set, clear, complement, invert, and isolate operands.
All logic instructions, except NOT, affect flag bits.

Common x86 Logic Instructions

NOT Op: Inverts each bit of the operand.
AND Dest, Source: Performs a bitwise AND operation on the destination and source operands, storing the result in the destination operand.
OR Dest, Source: Performs a bitwise OR operation on the destination and source operands, storing the result in the destination operand.
XOR Dest Source: Performs a bitwise XOR operation on the destination and source operands, storing the result in the destination operand.
TEST Op1, Op2: Performs a bitwise AND operation on two operands, setting the S, Z, and P status flags.

Logical Shifts

Shift bits left or right, losing the bit shifted out on one end and shifting in a zero on the other.
Useful for isolating fields within a word.

Arithmetic Shifts

Treat data as a signed integer.
Do not shift the sign bit during right shift.
Replicate the sign bit in the next position during a right arithmetic shift.
Perform a logical left shift on all bits except the sign bit during a left arithmetic shift.
Speed up certain arithmetic operations.

Cycling Shift (Rotate)

Preserve all bits being operated on.
Used to bring each bit successively into the leftmost bit for identification.

Common x86 Shift and Rotate Instructions

SAL Op, Qty: Shifts the bit positions to the left, clearing the empty bit positions.
SHR Op, Qty: Shifts the bit positions to the right, filling vacant positions with 0.
SAR Op, Qty: Shifts the bit positions to the right, filling vacant positions with the sign bit value.
ROL Op, Qty: Rotates bits to the left, with wraparound. The CF flag is loaded with the last bit shifted out.
ROR Op, Qty: Rotates bits to the right, with wraparound. The CF flag is loaded with the last bit shifted out.
RCL Op, Qty: Rotates bits to the left, including the CF flag, with wraparound. Treats the CF flag as a 1-bit extension on the upper end of the operand.
RCR Op, Qty: Rotates bits to the right, including the CF flag, with wraparound. Treats the CF flag as a 1-bit extension on the lower end of the operand.

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Description

Test your knowledge of basic arithmetic operations and x86 assembly language instructions. This quiz covers key operations such as addition, subtraction, and multiplication, along with their corresponding assembly instructions. Perfect for students and enthusiasts of computer architecture and programming.