C++ interface to x86/x86-64 registers and data structures
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README

libx86 -- C++ interface to x86/x86-64 registers and data structures
===================================================================

This library provides C++ interfaces for manipulating x86 and x86_64
register types and data structures. For example, to set the direction
flag in the hardware rflags register, you can use the following code:

	using namespace x86_64;
	rflags::write(rflags::read().direction_flag(true));

You can chain multiple changes like this:

	rflags::write(rflags::read()
		.direction_flag(true)
		.zero_flag(false)
		.overflow_flag(false));

If you simply want to read different parts of the register (without
actually reading it from the hardware more than once), you can store
the value in a variable:

	rflags x = rflags::read();
	printf("carry flag = %d\n", x.carry_flag());
	printf("parity flag = %d\n", x.parity_flag());

If you're an operating system kernel, you may wish to inspect a (paused)
thread's rflags that were pushed to the stack during interrupt or
system call entry. Then you would typically have a struct like this:

	struct task_state {
		...
		uint64_t rsp;
		uint64_t rflags;
		uint64_t rip;
		...
	};

Since x86_64::rflags is always a 64-bit POD (XXX: should be, anyway), you
can embed it in other structs and manipulate it as if it was the actual
hardware register:

	struct task_state {
		...
		uint64_t rsp;
		x86_64::rflags rflags;
		uint64_t rip;
		...
	};

	...

	void interrupt(struct task_state &current_task)
	{
		...
		printf("interrupted task:\n");
		printf("carry flag = %d\n", current_task.rflags.carry_flag());
		printf("parity flag = %d\n", current_task.rflags.parity_flag());
		...
	}


Contact
=======

Please send ideas, suggestions, patches, etc. to
Vegard Nossum <vegard.nossum@gmail.com>.

Disclaimer: The library is in a _very_ early stage. Don't expect it to be
able to do anything that I haven't needed to do with it myself already.