Assembly Flashcards
Where does assembly language fit in the software chain?
lowest level, deals directly with CPU, sits on top of machine code and reveals how processor manages/moves data for processing in single steps,
How is data represented in memory
grouped in sets of bytes (8 bits), represented by two-digit hex octet,common sets WORD (2 bytes); DWORD (4 bytes)
Location of stack
physically in RAM, it’s allocation allows for short term storage area for CPU and active programs
ID location of registers
resident memory inside CPU
In IA-32 registers, which are generic registers that can be used for any integer, Boolean, logical, or memory operation?
EAX, EBX, and EDX
In IA-32 registers, what is sometimes used as a counter by repetitive instructions that require counting, but is still a generic register?
ECX
In IA-32 registers, what are frequently used as a source and destination pointers in instructions that copy memory?
ESI & EDI (SI for Source Index, and DI for Destination Index)
In IA-32 registers, what points to the stack position right after the return address for the current function?
EBP (extended base pointer)
what stores the current position in the stack?
ESP (Extended Stack Pointer)
In IA-32 registers, what holds the address of the next line of code to be executed by the program? (so it is always pointing to the next thing to do)
EIP (Extended Instruction Pointer)
In IA-32, what are status registers, commonly used to influence jumps in assembly, as they all reflect the current state of the CPU, holds a value representing current state of processor?
EFLAGS
What state is the flag (EFLAGS) set to during an execution?
Set(1) or Cleared(0), based on result of the last operation.
What are instructions in assembly based around?
Operation code (opcode)
What is the size range of an opcode?
1-8 bytes
What are examples of opcodes?
MOV, CMP, AND, OR, XOR, etc
What comes after the opcode in assembly commands and is where data is stored?
Destination
What comes after the opcode and where data is stored and reflects where data is coming from?
Source
What is an example of a full assembly command?
MOV EAX, 0, which will move the value of 0 to the destination of EAX
What is the code for an unconditional jump and what does it do?
JMP, jumps to destination address no matter what
What jumps are conditional and based on the status of the Zero flag?
JZ, JNZ, JE
What jumps are conditional, and based on status of more than one flag that determine if the case is greater than or equal to, or less than or equal to?
JLE and JGE
What is an is a NOP command?
an opcode meaning No-Operation and it simply does nothing. execution simply proceeds to next instruction
