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

Assembler syntax
LDRD , , [, +/-] Offset: index==TRUE, wback==FALSE
LDRD , , [, +/-]! Pre-indexed: index==TRUE, wback==TRUE
LDRD , , [], +/- Post-indexed: index==FALSE, wback==TRUE
where:
See Standard assembler syntax fields on page A8-7.
The first destination register. This register must be even-numbered and not R14.
The second destination register. This register must be .
The base register. The SP or the PC can be used.
Instruction Details
+/- Is + or omitted if the value of is to be added to the base register value (add == TRUE), or
– if it is to be subtracted (add == FALSE).
Contains the offset that is applied to the value of to form the address.
The pre-UAL syntax LDRD is equivalent to LDRD.
Operation
if ConditionPassed() then
EncodingSpecificOperations();
offset_addr = if add then (R[n] + R[m]) else (R[n] - R[m]);
address = if index then offset_addr else R[n];
R[t] = MemA[address,4];
R[t2] = MemA[address+4,4];
if wback then R[n] = offset_addr;
Exceptions
Data Abort.
ARM DDI 0406B Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. A8-141