7.3 Some limitations and future extensions

The main limitation at present is that the foreign function call is not completely general. Both arguments and results are limited to being values of size at most 4 bytes. Such values can be:

• characters
• standard integers (short, long, signed or unsigned)
• simple floats (not doubles)
• enumerated constants
• machine pointers to general values (including structures and functions)

The final case allows general strings to be handled and general data to be used. In practice, this is only a limitation when a general struct value or a double needs to be passed or returned directly.

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MLWorks Reference Manual version 2.0 - 29 Jul 1998

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