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BFC

Bit Field Clear clears any number of adjacent bits at any position in a register, without affecting the other bits in the register.

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

A1

Decode for this encoding

let d : integer = UInt(Rd); let msbit : integer{} = UInt(msb); let lsbit : integer{} = UInt(lsb); if d == 15 then UnpredictableProcedure(); end; if msbit < lsbit then UnpredictableProcedure(); end;

CONSTRAINED UNPREDICTABLE behavior

If msbit < lsbit, then one of the following behaviors must occur:

• The instruction is undefined.
• The instruction executes as NOP.
• The value in the destination register is unknown.

T1

Decode for this encoding

let d : integer = UInt(Rd); let msbit : integer{} = UInt(msb); let lsbit : integer{} = UInt(imm3::imm2); // Armv8-A removes UNPREDICTABLE for R13 if d == 15 then UnpredictableProcedure(); end; if msbit < lsbit then UnpredictableProcedure(); end;

CONSTRAINED UNPREDICTABLE behavior

If msbit < lsbit, then one of the following behaviors must occur:

• The instruction is undefined.
• The instruction executes as NOP.
• The value in the destination register is unknown.

Assembler Symbols