bnei

Branch if not equal immediate

This instruction is defined by:

Encoding

Synopsis

Branch to PC + offset if the value in register xs1 is not equal to the XLEN-bit comparison constant decoded from cimm.

The cimm field is not sign-extended: cimm == 0 encodes the value -1, and cimm values 1 through 31 encode the corresponding positive integer values.

Raise a MisalignedAddress exception if the branch is taken and PC + offset is misaligned.

Access

M	HS	U	VS	VU
Always	Always	Always	Always	Always

Always

Decode Variables

signed Bits<13> offset = sext({$encoding[31], $encoding[7], $encoding[30:25], $encoding[11:8], 1'd0}, 13);
Bits<5> cimm = $encoding[24:20];
Bits<5> xs1 = $encoding[19:15];

Execution

Pruned, XLEN == 64
Original

XReg lhs = X[xs1];
XReg rhs = (cimm == 0) ? 64'hffffffffffffffff : cimm;
if (lhs != rhs) {
  jump_halfword($pc + $signed(offset));
}

XReg lhs = X[xs1];
XReg rhs = (cimm == 0) ? {MXLEN{1'b1}} : cimm;
if (lhs != rhs) {
  jump_halfword($pc + $signed(offset));
}