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Inside Macintosh: Mac OS Runtime Architectures /

Chapter 9 - CFM-68K Application and Shared Library Structure / CFM-68K Application Structure

The 'rseg' 1 Resource

The 'rseg'1 resource holds a PEF container consisting of the following sections:

• A data section containing the application's jump table, transition vector table, and global data, all in a compressed format. This section replaces the %A5Init segment used for classic 68K runtime applications.
• A loader section that specifies the import libraries needed by the application. This section also includes a list of symbols imported from each library and a list of symbols (if any) exported from the application.
• A code section containing the %_segLoader routine. This code patches the _LoadSeg and _UnloadSeg A-line instructions, so they can function properly in the CFM-68K runtime environment.

See Chapter 8, "PEF Structure," for more information about PEF containers.

The Code Fragment Manager uses the 'rseg' resources to create a direct data area, perform A5 relocations, and bind shared libraries to the application. While preparing the launch of a CFM-68K application, the Code Fragment Manager stores the 'rseg'1 resource in the application heap (much the way the %A5Init segment is stored for classic 68K applications). After preparations are complete, the Code Fragment Manager releases the 'rseg'1 resource.