Thanks for your input. The system I am refering to (Dynace OO
extension to C) already does what you describe by default. It has
support for an alternate "assembly language" mechinism that operates
faster becasue of the redused number of contexts to pop and returns to
execute. This mechinism is a core component of some very large systems
that perform this operation tens to hundreds of thousands of times per
second. So a small gain is a large gain.
Although I used assambly language many years ago, that world keeps
changing. These days my only use of assembly is this one piece of
code. I believe this is a trivial task for someone who uses it
regularly, so I really appreciate the help.
Incidently, in addition to being able to solve this problem in C only,
Dynace implements threads (the kind where multiple C functions can
share the same OS thread), and a mark-and-sweep garbage collector all
in C too. So there is a lot that can be done without assembler.
(Note, in addition to the above, Dynace also supports native/true
threads and other GCs like the Boehm-Demers-Weiser collector).
Thanks.
Blake McBride
On 2013-11-09 00:19:34 -0600, Sofiane Akermoun said:
Do you really need assembly to perform this?
Why func2 doesn't return a pointer on func4 to the caller func1?
This way func2 do this job, and return to func1 a pointer on a
function to call func4.
A very little, simple and naive simple:
#include <stdio.h>
void func4(char *str)
{
printf("%s", str);
}
void (*func2(void))(char *)
{
//we can imagine here some work on func2 that will decide what
function to return
return func4;
}
void func1(char *str)
{
//Here func2 return func4 pointer and
//it is used ny func1 to call func4 function with "str" argument
func2()(str);
}
int main(int argc, char *argv[])
{
func1("Hello world!");
return 0;
}
It is what you need?
kind regards,
Sofiane Akermoun
2013/11/9 Blake McBride <blake@xxxxxxxxxxx>:
I am trying to get a simple piece of x64 assembly working on 64 bit linux
and a Mac. I am using GCC.
Let's say I have 4 (C language) functions. Function fun1 calls fun2, fun2
calls fun3, and fun3 calls fun4. I need fun 4 to operate and run as if it
was called directly from fun1. So, fun4 should see the arguments passed to
fun2, and when fun4 returns it should return diretly to fun1 as if it was
called by fun1.
Basically, this is an OO language that uses fun2 to calculate what fun4 is.
fun3 is used to manipulate the stack so that when fun4 starts up it thinks
it was called directly from fun1. fin1, fun2, and fun4 are plain C code.
fun3 performs the magic. I have been doing this easily on many different 32
bit machines for years but I haven't been able to get it going on 64 bit
machines.
Typically fun3 would:
1. create a new stack frame
2. call fun3
3. pop local call frame
4. return
What I need fun3 to do is:
1. either pop its stack frame or don't create one
2. pop the stack frame from fun2
3. jump to fun4
Then fun4 will start executing as if it was called from fun1. I have sample
(errant) C code for the entire process. It will all work fine if fun3
(_jumpToMethod) is rewritten in assembler.
(What I did in the past was compile the C code for _jumpToMethod into
assembly code, modify the code, and then use that assembly code.)
Here is the C code for fun1, fun2, and fun3:
#include <stdio.h>
char *obj = "Some object pointer";
char *GenObj = "Some Generic Object Pointer";
typedef int (*ofun)();
int Method(char *self, int a, int b, int c) /* fun4 */
{
printf("Method reached with args %s %d %d %d\n", self, a, b, c);
return a + b + c;
}
ofun FindMethod(char *obj, char *gen)
{
return Method;
}
GenericFunction(char *self, ...) /* fun2 */
{
_jumpToMethod( FindMethod(self, GenObj) );
}
main(void) /* fun1 */
{
printf("Method is at %lx\n", (long unsigned int) &Method);
/* both calls to Method should look alike to Method */
int r = Method(obj, 1, 2, 3);
printf("Value returned from GenericFunction = %d\n", r);
r = GenericFunction(obj, 1, 2, 3);
printf("Value returned from GenericFunction = %d\n", r);
return 0;
}
-----------------------------------------------------------------
Here is the C code for _jumpToMethod (fun3)
void _jumpToMethod(void (*function) (/* ??? */))
{
/* pop_this_stack_frame; */
/* pop previous (generics) stack frame */
(*function)(); /* must be changed to jump instruction */
}
I think this would be easy for someone who knows this assembly language. I
have spent about 5 hurs on it and I am lost as I can be. Your help is
greatly appreciated!
Thanks!
Blake McBride
--
To unsubscribe from this list: send the line "unsubscribe linux-assembly" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Sofiane AKERMOUN
akersof@xxxxxxxxx
--
To unsubscribe from this list: send the line "unsubscribe linux-assembly" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
[Index of Archives]
[Kernel Newbies]
[Security]
[Linux C Programming]
[Linux for Hams]
[DCCP]
[Netfilter]
[Bugtraq]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux RAID]
[Linux Admin]
[Samba]
[Video 4 Linux]
