assembly function flow

Question

I am reading a \"programming from the ground up\", if you don\'t know what this book is, you still can help me.

In this book(chapter 4) there are 2 things that I don\'t

Answer 1

As Greg hinted, x86, like most mainstream architectures, does not have an instruction that copies data from memory to memory[1]. Thus, you must copy data using a separate load and store. First you load the data from the source memory into a register, then you store the data from that register to the destination memory. That's all that is happening here.

[1] I know, I know, but let's leave rep movs out of this and keep things simple.