What’s the difference between EAX, EBX, and ECX in assembly?
Nov 14, 2019 · 36 eax, ebx, ecx and so on are actually registers, which can be seen as "hardware" variables, somewhat similar to higher level-language's variables. Registers can be …
What does X mean in EAX,EBX,ECX ... in assembly?
Mar 30, 2010 · The following is a brief explanation of what each of the x86 general-purpose registers stands for: EAX: "Extended Accumulator" - used for arithmetic and logical operations, …
How exactly does the x86 LOOP instruction work? - Stack Overflow
Oct 23, 2017 · Use a smaller starting value for ecx so you get to the interesting ecx=1 part sooner. See also the x86 tag wiki for links to manuals, guides, and asm debugging tips at the bottom. …
assembly - Why take CMP ECX, ECX? - Stack Overflow
May 12, 2016 · 2 If the ECX register is zero then the repe cmpsb is not executed at all. This means that the following setb and seta instructions would produce garbage! Thus the …
what are the purpose of different types of assembly registers?
Jun 10, 2014 · For example, rep stos instructions use ECX as a counter and stored data into the memory pointed to by EDI. Nowadays, specialized instructions like that are not as commonly …
The using rules of %eax, %edx, %ecx in the same function frame
Jul 14, 2020 · eax, ecx and edx are scratch registers, they don't have to be preserved across function calls. All other 32-bit general-purpose registers must be saved on the stack, which …
x86 - imul assembly instruction - one operand? - Stack Overflow
imul also has an immediate form: imul ecx, ebx, 1234 does ecx = ebx * 1234. Many assemblers will accept imul ecx, 1234 as short-hand for imul ecx, ecx, 1234. These 32x32 => 32-bit forms …
Are the data registers EAX, EBX, ECX and EDX interchangeable
Nov 18, 2018 · For example, for the write system call, it grabs the file descriptor from ebx, a pointer to the buffer you want to write from ecx and the number of bytes you want to write from …
What is the correct way to loop if I use ECX in loop (Assembly)
Mar 19, 2017 · The advantage of loop is that it uses less instruction bytes. Think of it as a code-size optimization you can use if ECX happens to be a convenient register for looping, but at …
Difference between "mov eax, [num]" and "mov eax, num"
I wrote up a guide to x86 addressing modes, including covering the difference between NASM and MASM on this bit of syntax: mov ecx, num vs. mov ecx, OFFSET num. It was an attempt …