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Inside Macintosh: PowerPC System Software /

Chapter 3 - Code Fragment Manager / Code Fragment Manager Reference

Data Structures

Fragment Location Record

The fragLocator field of an initialization block contains a fragment location record that provides information about the location of a fragment. A fragment location record is defined by the FragmentLocator data type.

struct FragmentLocator {
   long                    where;         /*location selector*/
   union {
      MemFragment          inMem;         /*memory location record*/
      DiskFragment         onDisk;        /*disk location record*/
      SegmentedFragment    inSegs;        /*segment location record*/
   } u;
};
typedef struct FragmentLocator FragmentLocator, *FragmentLocatorPtr;

Field Description

where

A selector that determines which member of the following union is relevant. This field can contain one of these constants:

               enum {
                  kInMem,           /*container in memory*/
                  kOnDiskFlat,      /*container in a data fork*/
                  kOnDiskSegmented  /*container in a resource*/
               };

inMem

A memory location record.

onDisk

A disk location record.

inSegs

A segment location record.

IMPORTANT

The fields of a fragment location record are aligned in memory in accordance with 680x0 alignment conventions.