ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition

Assembler syntax
LDREX , [ {,#}]
where:
See Standard assembler syntax fields on page A8-7.
The destination register.
The base register. The SP can be used.
Instruction Details
The immediate offset added to the value of to form the address. can be omitted,
meaning an offset of 0. Values are:
Encoding T1 multiples of 4 in the range 0-1020
Encoding A1 omitted or 0.
Operation
if ConditionPassed() then
EncodingSpecificOperations(); NullCheckIfThumbEE(n);
address = R[n] + imm32;
SetExclusiveMonitors(address,4);
R[t] = MemA[address,4];
Exceptions
Data Abort.
ARM DDI 0406B Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. A8-143