Blog - Borland inline assembler - once again

and one again about assembler, well about inline assembly language. below we can see differences between pascal and c calling conventions: in c lang if we define function which returns custom structure/record ttest

ttest test _fnc( ttest z )

it will be interpreted as if it was defined as

void test_fnc( ttest *result_ptr, ttest z )

so now first argument of function isnt stored under [EBP+08h], where now is placed pointer to return value. pointer is 4bytes long so first argument can be found under [EBP+0ch]. to set up return structure, we will need to use pointer stored in [EBP+08h] to get to the return structure.
if we define the same function in delphi

function test_fnc( z : ttest) : ttest

delphi compiler will treat that function as a procedure of type

procedure test_fnc( z:ttest; var result:ttest )

in this case argument of our function will be pointed by EAX register, as we can see result structure of our function is treated as a second argument and EDX register points to it. so if we want to set up result value using assebler, we will just need to use EDX register.