
x86 64 - Why is the %rax register used in the assembly for this ...
Dec 9, 2020 · @RossRidge given %rax is the go-to register for storing return values, seeing it used in another way is surprising to me. It means that reading the disassembled code requires …
What is the difference between "mov (%rax),%eax" and "mov …
Dec 20, 2016 · In AT&T syntax, the instruction: mov (%rax), %eax # AT&T syntax or, equivalently in Intel syntax: mov eax, DWORD PTR [rax] ; Intel syntax dereferences the memory address …
How to read registers: RAX, RBX, RCX, RDX, RSP. RBP, RSI, RDI in C …
Dec 13, 2013 · @DavidHeffernan: I just want to read values that are currently in those registers: RAX, RBX, RCX, RDX, RSP. RBP, RSI, RDI and print them out, thats it.
assembly - How is "rax" different from "eax"? - Stack Overflow
Jul 7, 2017 · The registers starting with r as in rax, rbx, etc, are the 64-bit registers introduced with the AMD64 extension to the existing 32-bit x86 ISA. That ISA extension was subsequently …
x86_64 registers rax/eax/ax/al overwriting full register contents
As it is widely advertised, modern x86_64 processors have 64-bit registers that can be used in backward-compatible fashion as 32-bit registers, 16-bit registers and even 8-bit registers, for …
x86 - What do these assembly lines mean? - Stack Overflow
May 1, 2021 · I am struggling on a homework because I do not understand what these lines are supposed to mean ? mov rax, qword ptr [rbp - 0x28] mov rax, qword ptr [rax] mov eax, dword …
What does the R stand for in RAX, RBX, RCX, RDX, RSI, RDI, RBP, …
• RDX:RAX register pair representing a 128-bit operand See the question and answer for x86_64 registers rax/eax/ax/al overwriting full register contents as well as Why do most x64 …
assembly - What does 'callq * (%rax)' mean? - Stack Overflow
Jul 10, 2019 · Thus (%rax) means to get the value of the pointer currently stored in %rax. What does the star decoration do on that? Does that further dereference that value (thus (%rax) is …
assembly - How can I use MOV in asm? - Stack Overflow
Oct 3, 2021 · Either do lea rax, [rel a] or as an optimization in executables that are known to be linked into the low 32 bits of address space (like non-PIE on Linux), mov eax, a. Still, mov rax, …
assembly - How do AX, AH, AL map onto EAX? - Stack Overflow
RAX is the full 64-bit value, with EAX and its sub-components mapped to the lower 32 bits. The upper half of 64-bit registers is only accessible in 64-bit mode, unlike 32-bit registers which …