Inside Macintosh: Memory /

Chapter 2 - Memory Manager

This chapter describes how your application can use the Memory Manager to manage memory both in its own partition and outside its partition. Ordinarily, you allocate memory in your application heap only. You might, however, occasionally need to
access memory outside of your application partition, or you might want to create additional heap zones within your application partition.

You need to read this chapter if you want to use Memory Manager routines other than those described in the chapter "Introduction to Memory Management" in this book. That chapter shows how to use the Memory Manager and other system software components to perform the most common memory-manipulation operations while avoiding heap fragmentation and low memory situations. This chapter addresses a number of other important memory-related issues.

This chapter begins with a description of areas of memory that are outside your application's partition and their typical uses. Then it describes how you can

• allocate temporary memory
• allocate memory in and install code into the system heap
• read and change the values of system global variables
• allocate high memory during the startup process
• create additional heap zones within your application's partition
• install a purge-warning procedure for a heap zone

This chapter also addresses some advanced topics that are generally of use only to developers of very specialized applications or memory utilities. These advanced
topics include

• how the Memory Manager organizes heap zones
• how the Memory Manager organizes memory blocks

To use this chapter, you should be familiar with ordinary use of the Memory Manager and other system software components that allow you to manage memory, as described in the chapter "Introduction to Memory Management" earlier in this book.

The "Memory Manager Reference" and "Summary of the Memory Manager" sections in this chapter provide a complete reference and summary of the constants, data types, and routines provided by the Memory Manager.

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Chapter Contents

About the Memory Manager

Temporary Memory

Multiple Heap Zones

The System Global Variables

Using the Memory Manager

Reading and Writing System Global Variables

Extending an Application's Memory

Allocating Temporary Memory

Determining the Features of Temporary Memory

Using the System Heap

Allocating Memory at Startup Time

Creating Heap Zones

Installing a Purge-Warning Procedure

Organization of Memory

Heap Zones

Block Headers

Memory Manager Reference

Data Types

Memory Manager Routines

Setting Up the Application Heap

Allocating and Releasing Relocatable Blocks of Memory

Allocating and Releasing Nonrelocatable Blocks of Memory

Changing the Sizes of Relocatable and Nonrelocatable Blocks

Setting the Properties of Relocatable Blocks

Managing Relocatable Blocks

Manipulating Blocks of Memory

Assessing Memory Conditions

Freeing Memory

Grow-Zone Operations

Allocating Temporary Memory

Accessing Heap Zones

Manipulating Heap Zones

Application-Defined Routines

Grow-Zone Functions

Purge-Warning Procedures

Summary of the Memory Manager

Pascal Summary

Constants

Data Types

Memory Manager Routines

Application-Defined Routines

C Summary

Constants

Data Types

Memory Manager Routines

Application-Defined Routines

Assembly-Language Summary

Constants

Data Structures

Trap Macros

Global Variables

Result Codes