OpenEuphoria

Re: How to catch integer 64 bit return variable type

• Posted by D. Darmawan <skeydon_id at yahoo.co.id> Jun 08, 2007
• 611 views

CChris wrote:
> 
> I didn't test this because I don't have functions that return 64-bit
> integers. However, it should work using inline assembly.
> As far as I know, 64-bit values are returned in EDX:EAX. So the idea is
> to write some assembly that will call the function and store EDX and EAX
> in known places you'll peek4u() on return.
> }}}
<eucode>
> constant asm64_wrapper={
> 0,0,0,0, -- +0: address of function to call
> 0,0,0,0, -- +4: argument passed to it
> 0,0,0,0, -- +8: placeholder for EAX
> 0,0,0,0, -- +12:placeholder for EDX
> #FF,#35, -- +16:push dword mem
> 0,0,0,0, -- +18:patch with addr of second data dword
> #FF,#15, -- +22:call near dword
> 0,0,0,0, -- +24:patch with addr of 1st data dword
> #89,#D5, -- +28:mov dword [mem],EDX
> 0,0,0,0, -- +30:patch with addr of 4th dword
> #A3,     -- +34:mov dword [mem],EAX
> 0,0,0,0, -- +35:patch with 3rd adr
> #C3      -- +39:ret near
> }
> constant wrapper_address = allocate(length(asm64_wrapper))
> poke(wrapper_address,asm64_wrapper)
> -- patch position
> poke4(wrapper_address+18,wrapper_address+4)
> poke4(wrapper_address+24,wrapper_address)
> poke4(wrapper_address+30,wrapper_address+8)
> poke4(wrapper_address+35,wrapper_address+12)
> 
> atom my_callback,my_arg
> my_callback = callback(myAPIfunc)
> my_arg = allocate(length_of_my_struct)
> poke(my_arg,my_struct) 
> -- or whatever is more convenient, depending on the struct layout
> 
> constant toHiDword = 65536*65536 -- 2^32
> 
> function get_longlongsigned(atom callback,atom arg)
>    atom loDword,hiDword
>    poke4(wrapper_address,callback)
>    poke4(wrapper_address+4,arg)
>    call(wrapper_address+16) -- code to exec starts there
>    loDword=peek4u(wrapper_address+8)
>    hiDword=peek4s(wrapper_address+12)
> return loDword + hiDword * toHiDword
> end function
> 
> atom result
> result=get_longlongsigned(my_callback,my_arg)
> </eucode>
{{{

> 
> Of course, variants of the asm64_wrapper sequence will have to be devised
> whenever the prototype changes. Change peek4s() to peek4u() to retrieve
> unsigned long longs.
> 
> CChris

Thanks for your idea Chris...
I'll try it first...

Regards
Doni