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Making Code 64-Bit Clean

Before you begin to update your code, you should familiarize yourself with the document Mac OS X Technology Overview. After reading that document, the first thing you should do is compile your code with the -Wall compiler flag and fix any warnings that occur. In particular, make sure that all function prototypes are in scope, because out-of-scope prototypes can hide many subtle portability problems.

At a high level, to make your code 64-bit clean, you must do the following:

• Avoid assigning 64-bit long integers to 32-bit integers.

• Avoid assigning 64-bit pointers to 32-bit integers.

• Fix alignment issues caused by changes in data type sizes.

• Avoid pointer and long integer truncation during arithmetic operations.

Contents:

General Programming Tips
Data Type and Alignment Tips
Avoiding Pointer-to-Integer Conversion
Working with Bits and Bitmasks
Tools Tips
Alignment Pragmas
Sign Extension Rules for C and C-derived Languages
Velocity Engine and SSE Alignment Tips
Porting Assembly Language Code

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