ARM Cortex-M3 Podręcznik Użytkownika Pobierz pdf (Strona 51)

Programmers Model

ID072410 Non-Confidential

This means that software must not use load-multiple or store-multiple instructions to access a

device or access a memory region that is read-sensitive or sensitive to repeated writes. The

software must not use these instructions in any case where repeated reads or writes might cause

inconsistent results or unwanted side-effects.

Base register update in LDM and STM operations

There are cases when an

LDM

STM

updates the base register:

• When the instruction specifies base register write-back, the base register changes to the

updated address. An abort restores the original base value.

• When the base register is in the register list of an

LDM

, and is not the last register in the list,

the base register changes to the loaded value.

LDM

STM

is restarted rather than continued if:

• the instruction faults

• the instruction is inside an

If an

LDM

has completed a base load, it is continued from before the base load.

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ARM Cortex-M3 Podręcznik Użytkownika Strona 51