Arm VERSION 1.2 Uživatelský manuál stáhnout pdf (Strana 67)

100

101

Writing ARM and Thumb Assembly Language

2.10.4 Finding the end of the allocated data

You can use the

FIELD

directive with an operand of

to label a location within a

structure. The location is labeled, but the location counter is not incremented.

The size of the data structure defined in Example 2-19 depends on the values of

MaxStrLen

and

ArrayLen

. If these values are too large, the structure overruns the end of

available memory.

Example 2-19 uses:

• an

EQU

directive to define the end of available memory

• a

FIELD

directive with an operand of

to label the end of the data structure.

ASSERT

directive checks that the end of the data structure does not overrun the

available memory.

Example 2-19

StartOfData EQU 0x1000

EndOfData EQU 0x2000

MAP StartOfData

Integer FIELD 4

Integer2 FIELD 4

String FIELD MaxStrLen

Array FIELD ArrayLen*8

BitMask FIELD 4

EndOfUsedData FIELD 0

ASSERT EndOfUsedData <= EndOfData

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Arm VERSION 1.2 Uživatelský manuál Strana 67

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