© Thomas Kunz 2000
SCE 574
103
Difference with C Calling
Conventions
äC calling
conventions
äParameters are
passed by value only
äValues can be
addresses of variables (ie. &my_variable) so this isn’t a big restriction
äParameters are
passed in a reverse order
äSubroutine does not pop the parameters off the stack
before returning
äPop is done by the
caller
äSubroutine doesn’t
have to know how many parameters are passed to it
(it can be deduced at runtime) just RET
äOther
differences
äPascal assumes you
will not change the BP, DS, and SS registers and
the direction flag must be cleared
äC assumes SI, DP, BP
and direction flag will not be changed
äOther languages make
other assumptions about use of registers etc.,
order of parameters etc.
äInterlanguage calls
need pragmas to explain which calling conventions
should be used