x86::General Purpose Registers::EAX
Accumulator register - primarily used for common calculations, assigned one-byte opcodes for efficient calculations, also used for storing function return values
x86::General Purpose Registers::EBX
No special purpose in 32-bit architecture, often used as a catch-all for available storage
x86::General Purpose Registers::ECX
Counter register - used primarily for loop and counter iteration, can also store data
x86::General Purpose Registers::EDX
Data register - similar to EAX in purpose, used for mathematical operations often in conjunction with EAX, or to store function variables
x86::General Purpose Registers::ESI
Source index - often used to store the pointer to a read location
x86::General Purpose Registers::EDI
Destination index - Designed to hold storage pointers for functions, can be used to store data
x86::General Purpose Registers::EBP
Base pointer - Maintains pointer to base of stack, often used to locate objects in the stack by specifying base + offset
x86::General Purpose Registers::ESP
Stack pointer - Maintains pointer to top of stack, decrements/increments as objects are moved around, rarely ever used for any other purpose
x86::Special Purpose Registers::EIP
Instruction pointer - Maintains pointer to next instruction
x86::Segment Registers
Products of old addressing schemes and memory models, still used for backwards compatibility, other functions, and storage
x86::EFLAGS Register
Comprised of a series of flags that represent Boolean values, can be used for if/when logic, conditional jumps, etc
x86::Assembly::Instructions::ADD/SUB
Add or subtract two operands, store the result in the first operand
x86::Assembly::Instructions::XOR EAX, EAX
Exclusive or - in this case since the destination and source registers are the same, EAX will be zeroed out
x86::Assembly::Instructions::INC/DEC
Increment or decrement an operand by one
x86::Assembly::Instructions::CMP
Compare the value of two operands and set the appropriate EFLAGS value
x86::Assembly::Instructions::JMP
Jump, also includes conditional jump instructions such as je, jz. Used to move around within the execution flow/instruction set.
x86::Assembly::Instructions::MOV EAX, [ebx]
What do the brackets signify?
Brackets indicate that the value stored at the memory address contained within EBX should be moved into EAX, as opposed to the contents of EBX itself
Decimal 23
Hex __
Binary 00010111
0x18
