OpenEuphoria

Re: How to catch integer 64 bit return variable type

• Posted by D. Darmawan <skeydon_id at yahoo.co.id> Jun 16, 2007
• 730 views

Thanks Chris, Matt and Juergen,

I able to catch integer 64 bit return value now. It's solved.
I use Matt's fptr.e and made a little modification on call_cdcel function.
It's working on Linux and I've not tested this modification on Windows yet.

Here is the modified code on fptr.e I've made:
</eucode>
{{{

constant
fptr_cdecl_asm = {
    #60,                     --    0: pusha
    #BB,#00,#00,#00,#00,     --    1: mov ebx, paramcount (2)
    #B9,#00,#00,#00,#00,     --    6: mov ecx, params (7)
                             --    B: start: 
    #8B,#01,                 --    B: mov eax, [ecx]
    #50,                     --    D: push eax
    #83,#C1,#04,             --    E: add ecx, 4
    #4B,                     --   11: dec ebx
    #75,#F7,                 --   12: jnz start
    #FF,#15,#00,#00,#00,#00, --   14: call dword ptr [comfunc] (22) 
    #A3,#00,#00,#00,#00,     --   1A: mov [retpointer], eax (27)
#89,#15,#00,#00,#00,#00, --   1F: mov [retpointer], edx (33) --- additional
    bytecode
    #83, #C4, 00,            --   25: add esp 0 (39 or #27)
    #61,                     --   28: popa
    #C3},                    --   29: ret


fptr_cdecl_paramcount = 2,
fptr_cdecl_params = 7,
fptr_cdecl_funcptr = 22,
fptr_cdecl_retptrLo = 27,  --- fptr_cdecl_retptr
fptr_cdecl_retptrHi = 33,  --- additional new pointer
cdecl_retval = allocate(4),

fptr_cdecl_asm_addr = allocate( length( fptr_cdecl_asm ) + 20 * 4 )

constant
--- changed from #24 to #2A
fptr_cdecl_func = fptr_cdecl_asm_addr + #2A,          
fptr_cdecl_retvalLo = fptr_cdecl_asm_addr + #2A + 4,
fptr_cdecl_retvalHi = fptr_cdecl_asm_addr + #2A + 8,   --- insert new pointer
for edx value
fptr_cdecl_param_ptr = fptr_cdecl_asm_addr + #2A + 12  --- changed from #24 + 8 

poke( fptr_cdecl_asm_addr, fptr_cdecl_asm )
poke4( fptr_cdecl_asm_addr + fptr_cdecl_funcptr, fptr_cdecl_func )
poke4( fptr_cdecl_asm_addr + fptr_cdecl_params, fptr_cdecl_param_ptr )
poke4( fptr_cdecl_asm_addr + fptr_cdecl_retptrLo, fptr_cdecl_retvalLo )
poke4( fptr_cdecl_asm_addr + fptr_cdecl_retptrHi, fptr_cdecl_retvalHi ) ---
additional line


--/topic Calling functions
--/func call_cdecl( atom fptr, sequence params )
--/ret Return value of fptr
--/desc Calls a function using cdecl
--Calls a function using stdcall
--Use this to call a function using the stdcall calling convention when you
--have a pointer to the function.  This is the most common calling convention in
--Linux.  You can get the pointer to a function in a 
--.dll or .so using /b define_c_var() instead of /b define_c_func().  You should
--discard the return value if you call a routine that does not return a value.

global function call_cdecl( atom fptr, sequence params )
    atom ret
    
    -- store the pointer to the function
    poke4( fptr_cdecl_func, fptr )

    -- reverse the params for stdcall calling convention
    params = reverse(params)

    -- store the params
    poke4( fptr_cdecl_param_ptr, params )

    -- tell the asm how many params to push/pop
    poke4( fptr_cdecl_asm_addr + fptr_cdecl_paramcount, length(params) )
    poke( fptr_cdecl_asm_addr + #27, length(params) * 4) --- changed #21 to #27
    
    -- run the asm
    call( fptr_cdecl_asm_addr )

    -- get the value returned from the function
ret = peek4u( fptr_cdecl_retvalLo ) + peek4s( fptr_cdecl_retvalHi ) *
    #100000000 -- modified
    return ret

end function
</eucode>
{{{



And sqlite3 wrapper has been modified to:

include fptr.e
---
---
global function sqlite_column_int(atom db, atom stmt, integer column_num)
integer ptr
     
     ptr = define_c_var(sqlite3_dll, "sqlite3_column_int64")
     return call_cdecl(ptr, {stmt, column_num - 1 })

end function

Regards,
Doni