RealView Compilation Tools - ARM Information Center

Compiler-specific Features
#ifndef FILE_H
#define FILE_H
#pragma once
// optional ... body of the header file ...#endif
The #pragma once is marked as optional in this example. This is because the compiler
recognizes the #ifndef header guard coding and skips subsequent includes even if
#pragma once is absent.
4.6.18 #pragma Ospace
This pragma instructs the compiler to perform optimizations to reduce image size at the
expense of a possible increase in execution time.
See also
• #pragma Otime
• -Ospace on page 2-99
4.6.19 #pragma Otime
This pragma instructs the compiler to perform optimizations to reduce execution time
at the expense of a possible increase in image size.
See also
• #pragma Ospace
• -Otime on page 2-99.
4.6.20 #pragma pack(n)
This pragma aligns members of a structure to the minimum of n and their natural
alignment. Packed objects are read and written using unaligned accesses.
Syntax
#pragma pack(n)
Where:
n is the alignment in bytes, valid alignment values being 1, 2, 4 and 8.
Default
The default is #pragma pack(8).
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