When compiling your software to link with external libraries (any OS), or producing your own libraries, there are conventions to calling external libraries. These calling conventions define to the compiler how data is passed between the application and library layers. The calling conventions also define which layer is responsible for cleaning up the stack if used for passing information. My research notes on name mangling explains how these calling conventions modify the name the exported methods to avoid conflicts.



     The above chart may be misleading at first, as it looks like there are only a few combination with just different names/aliases. That assumption is incorrect, the above chart should be used to know which layer cleans-up the stack and the order in which the parameters are passed. Below I actually document the internal methods used for these calling conventions, and you will quickly see each one works at least a little bit different from each other - some are drastically different.

cdecl

     The cdecl calling convention is used by many "C" languages for the Intel CPU. Parameters are pushed on the stack in right-to-left order. Result values are returned using the EAX register (except for floating point values, which are returned in the x87 register ST0). Registers EBX, ECX and EDX are available for use in the called routine.

function external_function(a,b,c:Integer):Integer;
   external; cdecl;
{...}
d := external_function(a, b, c);

in assembly routine look like:

G.E. Ozz Nixon Jr.

Brian Ellixson
FreePascal User