Reverse Engineering Stack Exchange is a question and answer site for researchers and developers who explore the principles of a system through analysis of its structure, function, and operation. It only takes a minute to sign up.
Sign up to join this community
Some of the general purpose registers are used for some specific reasons. For example EAX is used as an accumulator and to store return values, ECX is used as a counter, ESI and EDI are used to store the src and dst address, respectively. similarly, ESP and EBP.
Is there any specific use case forEBX register? and Is there anything else that I have missed special use cases of general purpose registers?
Thank you.
• AX/EAX/RAX: Accumulator
• BX/EBX/RBX: Base index (for use with arrays)
• CX/ECX/RCX: Counter
• DX/EDX/RDX: Data/general
• SI/ESI/RSI: Source index for string operations.
• DI/EDI/RDI: Destination index for string operations.
• SP/ESP/RSP: Stack pointer for top address of the stack.
• BP/EBP/RBP: Stack base pointer for holding the address of the current stack frame.
• IP/EIP/RIP: Instruction pointer. Holds the program counter, the current instruction address.
Segment registers:
• CS: Code Segment (used for IP)
• DS: Data Segment (used for MOV)
• SS: Stack Segment (used for SP)
• ES: Destination Segment (used for MOVS, etc.)
• FS: local store
• GS: local store
loop which works on cx or its extensions, but most instructions that needed a specific (set of) register(s) on 8086 work with any, or almost any, register now.
May 25, 2015 at 14:20