Mar 96 Tips

Volume Number: 12

Issue Number: 3

Column Tag: Tips & Tidbits

Tips & Tidbits

By Steve Sisak, Contributing Editor

Note: Source code files accompanying article are located on MacTech CD-ROM or

source code disks.

Calling PowerPC Code

From 68K Code

There is a lot of information out there about calling 68K code from PowerPC

code, but there is very little about calling PowerPC code from 68K code.

Here is a nice method for calling PowerPC code from 68K code. I am using

CodeWarrior 7. This is a bit lengthy so hang in there:

There are three steps required to get things up and running. Let’s look at a

sample scenario:

You have a 68K application that you just can’t convert to PowerPC code (I don’t

know why you can’t convert it, but just bear with me), but you can take some of the

time-critical code and convert it to a PowerPC shared library and call it from the 68K

code.

Suppose you have two functions that perform data compression:

long CompressData( unsigned char *inBuffer,

unsigned char *outBuffer,

unsigned long inBufferSize );

long UncompressData( unsigned char *inBuffer,

unsigned char *outBuffer,

unsigned long inBufferSize );

Step 1 - Create a PPC shared library containing your functions.

We are going to export these functions using the #pragma export directive. This

is set in the PPC Prefs area of Codewarrior preferences.

“the shared library”

// Prototypes

#pragma export on

#ifdef __cplusplus

extern "C" {
#endif

long CompressData( unsigned char *inBuffer,

unsigned char *outBuffer,

unsigned long inBufferSize );

long UncompressData( unsigned char *inBuffer,

unsigned char *outBuffer,

unsigned long inBufferSize );

Referenced by (2):