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

Assembler syntax
STREXB , , []
where:
See Standard assembler syntax fields on page A8-7.
The destination register for the returned status value. The value returned is:
0 if the operation updates memory
1 if the operation fails to update memory.
The source register.
The base register. The SP can be used.
Operation
if ConditionPassed() then
EncodingSpecificOperations(); NullCheckIfThumbEE(n);
address = R[n];
if ExclusiveMonitorsPass(address,1) then
MemA[address,1] = R[t];
R[d] = 0;
else
R[d] = 1;
Exceptions
Data Abort.
Aborts
If a synchronous Data Abort exception is generated by the execution of this instruction:
memory is not updated
is not updated.
Instruction Details
If ExclusiveMonitorsPass() returns FALSE and the memory address would generate a synchronous Data
Abort exception if accessed, it is IMPLEMENTATION DEFINED whether the exception is generated.
ARM DDI 0406B Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. A8-403