Apple Darwin User Manual download pdf (Page 18)

#endif

Avoid casting pointers to non pointers. You should generally avoid casting a pointer to a non-pointer type

for any reason (particularly when performing address arithmetic). Alternatives are described in Avoiding

Pointer-to-Integer Conversion (page 22).

Update assembly code. Any assembly code needs to be rewritten because 64-bit Intel assembly language is

significantly different from its 32-bit counterpart. For more information, see Porting Assembly Language

Code (page 27).

Any assembly code that directly deals with the structure of the stack (as opposed to simply using pointers to

variables on the stack) must be modified to work in a 64-bit environment. For more information, see OS X ABI

Mach-O File Format Reference.

Fix format strings. Print functions such as printf can be tricky when writing code to support 32-bit and

64-bit platforms because of the change in the sizes of pointers. To solve this problem for pointer-sized integers

(uintptr_t) and other standard types, various macros exist in the inttypes.h header file.

The format strings for various data types are described in Table 3-1. These additional types, listed in the

inttypes.h header file, are described in Table 3-2.

Table 3-1 Standard format strings

Format stringType

%dint

%ldlong

%lldlong long

%zusize_t

%tdptrdiff_t

%pany pointer

Table 3-2

Additional inttypes.h format strings (where N is some number)

Format stringType

PRIdNintN _t (such as int32_t)

Making Code 64-Bit Clean

General Programming Tips

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Apple Darwin User Manual Page 18