Integer Arithmetic

A series of flashcards covering key concepts, instructions, and operations related to integer arithmetic in assembly language.

What do shift instructions like SHL and SHR primarily accomplish in assembly language?

Shift instructions modify the bit positions of operands to perform arithmetic operations such as multiplication or division.

What is the outcome of the SHL (Shift Left) instruction on a number?

Shifting left by n bits multiplies the operand by 2^n.

What happens to the sign bit during an arithmetic shift?

An arithmetic shift fills the newly created bit position with a copy of the sign bit.

In the context of assembly language, what does the SHR instruction do?

The SHR (Shift Right) instruction performs a logical right shift, filling the highest bit position with zero.

What is the purpose of the ROL (Rotate Left) instruction?

The ROL instruction shifts each bit to the left and copies the highest bit into both the Carry flag and the lowest bit.

What is the primary function of the RCR (Rotate Carry Right) instruction?

RCR shifts each bit to the right and copies the Carry flag into the most significant bit.

What does the acronym ADC stand for in assembly language?

ADC stands for 'Add with Carry', which adds the source operand and the Carry flag to the destination.

What are the consequences of overflow in unsigned arithmetic operations?

Overflow in unsigned arithmetic is indicated by the Carry flag exceeding its expected value.

How does the IMUL instruction differ from the MUL instruction?

IMUL performs signed multiplication, preserving the sign, whereas MUL performs unsigned multiplication.

What is the purpose of the CBW instruction?

CBW (Convert Byte to Word) extends the byte in AL to a word in AX.

What occurs during a signed division operation using the IDIV instruction?

IDIV performs signed integer division and requires the dividend to be sign-extended before division.

What does the term 'packed decimal' refer to in assembly language?

Packed decimal stores two decimal digits per byte, commonly used for financial calculations.

What is the result of the DAS (Decimal Adjust After Subtraction) instruction?

DAS adjusts the binary result of a subtraction operation to conform to packed decimal format.

What does the AAD instruction do before a division operation?

AAD adjusts the unpacked BCD dividend in AX for division.

In the context of the AAA instruction, what does it adjust?

The AAA instruction adjusts the result of an ADD operation to ensure it conforms to ASCII decimal representation.

How does an arithmetic right shift (SAR) differ from a logical right shift (SHR)?

SAR preserves the sign bit by filling with the sign bit while SHR fills with zero.

What is the function of the DAA instruction?

DAA converts the binary result of an addition operation to packed decimal format.

What instruction should be used before performing signed division with IDIV?

Before IDIV, the value should be converted or extended, typically using CBW, CWD, or CDQ.

What is meant by 'extended precision arithmetic' in assembly language?

Extended precision arithmetic allows for the addition or subtraction of operands larger than the standard word size, using carry values to manage overflow.

What is the result of shifting an entire array of doublewords?

It modifies the bit positions of all elements in the array simultaneously, which can be useful for tasks like moving graphics.