C251 User's Guide

Parameter Passing Symbols

Function arguments were historically passed using fixed memory locations. The C251 compiler can pass up to 9 function arguments in registers. Other arguments are passed using the traditional fixed memory areas. Since the parameter areas must be publicly known to any calling module, they are publicly defined using the following symbol names:

?function?BYTE
?function?BIT

For example, if func1 is a function that accepts both bit arguments as well as arguments of other data types, the bit arguments are passed starting at ?FUNC1?BIT, and all other parameters are passed starting at ?FUNC1?BYTE. Depending on the memory model, the ?function?BYTE symbol refers to a DATA, EDATA or XDATA memory location. Refer to the example routines in the Overlaying Segments topic for function argument symbols examples.