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Home > A32 and T32 Instructions > LDAEX |
Load-Acquire Register Exclusive.
LDAEX{
} cond
, [Rt
]
Rn
LDAEXB{
} cond
, [Rt
]
Rn
LDAEXH{
} cond
, [Rt
]
Rn
LDAEXD{
} cond
, Rt
, [Rt2
]
Rn
where:
cond
Rt
Rt2
Rn
LDAEX
loads data from memory.
LDAEX
tags the physical
address as exclusive access for the current processor, and clears
any exclusive access tag for this processor for any other physical
address.LDAEX
in
program order, then all observers are guaranteed to observe the LDAEX
before
observing the loads and stores. Loads and stores appearing before LDAEX
are
unaffected.The PC must not be used for any of
, Rt
, or Rt2
.Rn
For A32 instructions:
Rt
, or Rt2
is deprecated.LDAEXD
, Rt
must be an even numbered register,
and not LR.Rt2
must be R(t+1)
.For T32 instructions:
Rn
, but must not be used for any of Rt
, or Rt2
.LDAEXD
, Rt
and Rt2
must not be the same register.Use LDAEX
and STLEX
to
implement interprocess communication in multiple-processor and shared-memory
systems.
For reasons of performance, keep the number of instructions
between corresponding LDAEX
and STLEX
instructions
to a minimum.
STLEX
instruction
must be the same as the address in the most recently executed LDAEX
instruction.
These 32-bit instructions are available in A32 and T32.
There are no 16-bit versions of these instructions.