Writing ARM and Thumb Assembly Language

2.10Describing data structures with MAP and FIELD directives

You can use the MAP and FIELD directives to describe data structures. These directives are always used together.

Data structures defined using MAP and FIELD:

are easily maintainable

can be used to describe multiple instances of the same structure

make it easy to access data efficiently.

The MAP directive specifies the base address of the data structure. Refer to MAP on page 7-15 for further information.

The FIELD directive specifies the amount of memory required for a data item, and can give the data item a label. It is repeated for each data item in the structure. Refer to FIELD on page 7-16 for further information.

Note

No space in memory is allocated when a map is defined. Use define constant directives (for example, DCD) to allocate space in memory.

ARM DUI 0068B

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ARM VERSION 1.2 manual Describing data structures with MAP and Field directives