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LDREX

Load Register Exclusive calculates an address from a base register value and an immediate offset, loads a word from memory, writes it to a register and:

• If the address has the Shared Memory attribute, marks the physical address as exclusive access for the executing PE in a global monitor.
• Causes the executing PE to indicate an active exclusive access in the local monitor.

For more information about support for shared memory see Synchronization and semaphores. For information about memory accesses see Memory accesses.

It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) .

A1

Decode for this encoding

let t : integer = UInt(Rt); let n : integer = UInt(Rn); let imm32 : bits(32) = Zeros{}; // Zero offset if t == 15 || n == 15 then UnpredictableProcedure(); end;

T1

Decode for this encoding

let t : integer = UInt(Rt); let n : integer = UInt(Rn); let imm32 : bits(32) = ZeroExtend{}(imm8::'00'); // Armv8-A removes UNPREDICTABLE for R13 if t == 15 || n == 15 then UnpredictableProcedure(); end;

Assembler Symbols