rol

Rotate left (Register)

This instruction is defined by:

Encoding

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Synopsis

Performs a rotate left of xs1 by the amount in least-significant log2(XLEN) bits of xs2.

Access

M HS U VS VU

Always

Always

Always

Always

Always

Decode Variables

Bits<5> xs2 = $encoding[24:20];
Bits<5> xs1 = $encoding[19:15];
Bits<5> xd = $encoding[11:7];

Execution

  • Pruned, XLEN == 64

  • Original

if ((CSR[misa].B == 1'b0)) {
  raise(ExceptionCode::IllegalInstruction, mode(), $encoding);
}
XReg shamt = X[xs2][5:0];
X[xd] = (X[xs1] << shamt) | (X[xs1] >> (64 - shamt));
if (implemented?(ExtensionName::B) && (CSR[misa].B == 1'b0)) {
  raise(ExceptionCode::IllegalInstruction, mode(), $encoding);
}
XReg shamt = (xlen() == 32) ? X[xs2][4:0] : X[xs2][5:0];
X[xd] = (X[xs1] << shamt) | (X[xs1] >> (xlen() - shamt));

Exceptions

This instruction may result in the following synchronous exceptions:

  • IllegalInstruction