Format
#include <stdlib.h> /* also in <builtin.h> */ unsigned char __parmdwords(void);
Language Level: Extension
The __parmdwords function returns the hidden parameter passed in
the AL register for _System linkage calls. The hidden parameter
contains the size of the parameter list that is passed to the
function containing the call to __parmdwords. The size is in
doublewords (dwords), and can be between 0 and 255. If the
parameter list is larger than 255 dwords, the hidden parameter
contains the 8 least significant bits of the value.
Note: To use __parmdwords, you must compile with the /Gp+ option to include the support for it.
This function allows the implementer of a function to increase the number of parameters the function takes without changing the name of the function. The new version of the function can call __parmdwords to check the size of the parameter list and determine whether the call was written for the earlier version of the function or for the extended version.
Warning! The __parmdwords function has several limitations:
Return Value
The __parmdwords function returns the size of the
parameter list passed to the function in units of dwords.
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<stdlib.h>
/Gp compiler option