C Compilers Reference, Pragmas

[ First ] [ Previous ] [ Next ] [ Last ] [ Manuals ]

mpwc

Description:

Controls the use of Apple's MPW C calling conventions.

Compatibility:

This pragma is compatible with the following platform targets:

68K
PowerPC
NEC V800
Intel x86
MIPS
Embedded 68K

Prototype:

#pragma mpwc on | off | reset

Remarks:

This pragma applies to Mac OS on 68K processors only.

When the pragma mpwc is on, the compiler does the following to be compatible with MPW C's calling conventions:

Passes any integral argument that is smaller than 2 bytes as a sign-extended long integer. For example, the compiler converts this declaration:

int MPWfunc ( char a, short b, int c, long d, char *e );

To this:

long MPWfunc( long a, long b, long c, long d, char *e );

Passes any floating-point arguments as a long double. For example, the compiler converts this declaration:

void MPWfunc( float a, double b, long double c );

To this:

void MPWfunc( long double a, long double b, long double c );

Returns any pointer value in D0 (even if the pragma pointers_in_D0 is off).
Returns any 1-byte, 2-byte, or 4-byte structure in D0.
If the 68881 Codegen option is on, returns any floating-point value in FP0.

This pragma corresponds to the MPW C Calling Convention option in the 68K Processor settings panel. To check whether this option is on, use __option (mpwc), described in "Checking Options."

[ First ] [ Previous ] [ Next ] [ Last ] [ Manuals ]

Visit the Metrowerks website at: http://www.metrowerks.com
For assistance contact Metrowerks Technical Support at: cw_support@metrowerks.com
Copyright © 2000, Metrowerks Corp. All rights reserved.

Last updated: August 17, 2000