I am beginning to port a program which is written in C and have several pieces of code written in assembly with instructions for a 32 bit machine – like ljmp – to a 64 bits machine.
Is there a place/document that have the instructions, in assembly, for a 32 bit machine and its counterpart for a 64 one? If not, where can I find a document that lists all the instructions for a 32 bit and a 64 bit machine?
As it’s is pretty obvious, I am a newbie for the situation. Let’s clarify some points.
I am porting a OS in its very early days. It was written with a x86 machine in mind. Now, I want it to run at a x86_64.
It is written in a Linux box with UNIX in mind. I am almost sure that the original author is writing it at a Intel machine. I am also on Intel but I would like to run the OS in AMD too.
The compiler used is gcc.
Read this first: http://x86asm.net/articles/x86-64-tour-of-intel-manuals/index.html.
Then download the instruction set reference here: http://developer.intel.com/products/processor/manuals/index.htm.