x86 Assembly

Flashcard 1

Question: How do you find the 16-bit hexadecimal value of -78? Answer:

Take the absolute value of the number.
Convert it to hexadecimal.
Take the two's complement of the number:
- One's complement: subtract FF from the number.
- Then add one. Result: FFB2h

Flashcard 2

Question: What is the result of the following binary subtraction: 10101000b - 00101111b? Answer: The result is 01111001b.

Flashcard 3

Question: How do you convert ABh to an 8-bit decimal value? Steps:

Take the two's complement.
Convert to decimal. Answer: 55

Flashcard 4

Question: What assembly instructions set the overflow flag using mov al, 85h; sub al, 6;? Answer: True, these instructions set the overflow flag.

Flashcard 5

Question: What is the value in EAX after executing the following assembly lines?

.data
num word 0ABCDh
.code
mov eax, 0FFFFFFFh
movzx eax, num Answer: The value in EAX is 00000ABCDh.

Flashcard 6

Question: What value will be in EAX after executing mov eax, 101FFFFh; inc eax;? Answer: The value will be 1020000h.

Flashcard 7

Question: What is the value in EDX after the following assembly lines execute?

mov edx, 0
mov eax, 8000h
cmp eax, 7FFFh
jg L1
mov edx, 1
L1: Answer: EDX is 1 (because 8000h > 7FFFh).

Flashcard 8

Question: What does the assembly statement mov ebx, dword ptr arr+4 do when arr consists of byte values from 10h to 80h? Answer: It moves the last four bytes of arr (50h, 60h, 70h, 80h) into the EBX register.

Flashcard 9

Question: What is the effect of the assembly statement and al, 1111011b on the AL register? Answer: It clears bit 2 of the value in AL.

Flashcard 10

Question: What is the effect of the assembly statement or al, 00000100b on the AL register? Answer: It sets bit 2 of the value in AL.

Flashcard 11

Question: How do you retain the upper half and invert the lower half of a 16-bit value in AX using assembly? Instruction: xor ax, 00FFh Answer: This XORs the lower byte of AX with FFh, inverting the lower half.

Flashcard 12

Question: What assembly instruction on line 2 will set the overflow flag after mov al, 7fh? Instruction: dec al Answer: This will set the overflow flag because decrementing 7Fh from AL causes an overflow.

Flashcard 13

Question: What is the value in AX after executing multiple MOV operations accessing various memory types and offsets? Steps Executed:

mov ax, var2+1
mov ax, [var2+4]
mov ax, [var3+2]
mov eax, var4-4 Answer: The value in AX is 80009000h.

Flashcard 14

Question: What is the total size of the Customer structure, considering alignment adjustments in an x86 architecture? Answer: The total size of the Customer structure is 102 bytes, considering alignment for AccountId and OrderHistory to ensure proper data access and system performance.

These flashcards can be used to test your knowledge on the relevant subjects, especially as it pertains to assembly programming and memory management. If there are any additional details or another format you need, let me know!

You

Now add flash cards on the x86 flags seen in the questions in addition to the or,and,xor instructions. Additionalyl add flash cards for the jump instructions

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Certainly! Let's add flashcards covering the x86 flags affected by the OR, AND, and XOR instructions, as well as details about jump instructions used in the assembly code examples from the questions:

Flashcard 15

Question: How does the AND instruction affect the flags in the x86 processor? Answer: The AND instruction affects the Zero (ZF), Sign (SF), Parity (PF), and Overflow (OF) flags:

ZF is set to 1 if the result is zero, otherwise 0.
SF is set according to the most significant bit (sign bit) of the result.
PF is set if the number of set bits in the result is even.
OF and CF (Carry Flag) are cleared to 0.

Flashcard 16

Question: How does the OR instruction affect the flags in the x86 processor? Answer: The OR instruction affects the Zero (ZF), Sign (SF), Parity (PF), Overflow (OF), and Carry (CF) flags:

ZF is set to 1 if the result is zero, otherwise 0.
SF is set based on the most significant bit of the result.
PF is set if the number of 1 bits in the result is even.
OF and CF are cleared to 0.

Flashcard 17

Question: How does the XOR instruction affect the flags in the x86 processor? Answer: The XOR instruction affects the Zero (ZF), Sign (SF), Parity (PF), Overflow (OF), and Carry (CF) flags:

ZF is set to 1 if the result is zero, otherwise 0.
SF is set according to the most significant bit of the result.
PF is set if the number of 1 bits in the result is even.
OF and CF are cleared to 0.

Flashcard 18

Question: What are the effects and conditions checked by the JG (Jump if Greater) instruction in x86 assembly? Answer: JG (Jump if Greater) checks the Zero Flag (ZF) and the Sign Flag (SF) compared to the Overflow Flag (OF):

It jumps if ZF is 0 and SF equals OF.
This instruction is used to jump based on the results of a signed comparison.

Flashcard 19

Question: What x86 flags would be typically observed and used after performing a subtraction (sub) in assembly, like sub al, 6? Answer: After a sub operation, several flags can be affected:

CF (Carry Flag): Set if there is a borrow in binary subtraction.
ZF (Zero Flag): Set if the result is zero.
SF (Sign Flag): Set based on the result's most significant bit (negative result if set).
OF (Overflow Flag): Set if there is a signed overflow.
PF (Parity Flag): Set if the low-order 8 bits of the result contain an even number of 1 bits.

Flashcard 20

Question: Describe the function of the CMP and JZ (Jump if Zero) instructions in x86 assembly. Answer:

CMP (Compare): Subtracts the second operand from the first operand and sets the flags based on the result, similar to the SUB instruction but does not store the result.
JZ (Jump if Zero): Checks the Zero Flag (ZF). It causes a jump to the specified label if ZF is set to 1, indicating that the result of the last comparison or arithmetic operation was zero.