David Brown <da...@westcontrol.com> writes:
> Personally, I've used "naked" when I want to write pure assembly code
> and don't want extra stack frames or "return" codes. I don't want to
> write stand-alone assembly files (I've written mountains of them in the
> past, and hope they stay in the past). I am happier using the very nice
> flexible gcc inline assembly syntax.
The full inline asm syntax, such as:
asm ("..." : "=r" (result) : "i" (100))
is specifically forbidden in naked functions, because in general GCC can
only satisfy the constraints by building its own frame:
Use this attribute on the ARM, AVR, MCORE, RX and SPU ports to indicate that
the specified function does not need prologue/epilogue sequences generated by
the compiler. It is up to the programmer to provide these sequences. The
only statements that can be safely included in naked functions are
@code{asm} statements _that do not have operands_. All other statements,
including declarations of local variables, @code{if} statements, and so
forth, should be avoided.
(my emphasis). Naked functions must have a body of the form:
{
asm ("....");
}
i.e. an asm with just a plain string, and no other statements or
local variables. So you don't really get any more flexibility
by using inline asms over using assembly files.
Thanks,
Richard
