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

Assembler syntax
BFC , #, #
where:
See Standard assembler syntax fields on page A8-7.
The destination register.
Instruction Details
The least significant bit that is to be cleared, in the range 0 to 31. This determines the
required value of lsbit.
The number of bits to be cleared, in the range 1 to 32-. The required value of msbit is
+-1.
Operation
if ConditionPassed() then
EncodingSpecificOperations();
if msbit >= lsbit then
R[d] = Replicate(‘0’, msbit-lsbit+1);
// Other bits of R[d] are unchanged
else
UNPREDICTABLE;
Exceptions
None.
ARM DDI 0406B Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. A8-47