ror

Rotate right (Register)

This instruction is defined by:

  • anyOf:

    • Zbb, version >= Zbb@1.0.0

    • Zbkb, version >= Zbkb@1.0.0

This instruction is included in the following profiles:

  • RVA22S64 (Mandatory)

  • RVA22U64 (Mandatory)

  • RVA23M64 (Mandatory)

  • RVA23S64 (Mandatory)

  • RVA23U64 (Mandatory)

  • RVB23M64 (Mandatory)

  • RVB23S64 (Mandatory)

  • RVB23U64 (Mandatory)

Encoding

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Assembly format

ror rd, rs1, rs2

Synopsis

This instruction must have data-independent timing when extension Zkt is enabled.

This instruction performs a rotate right of rs1 by the amount in least-significant log2(XLEN) bits of rs2.

Access

M HS U VS VU

Always

Always

Always

Always

Always

Decode Variables

Bits<5> rs2 = $encoding[24:20];
Bits<5> rs1 = $encoding[19:15];
Bits<5> rd = $encoding[11:7];

Execution

  • IDL

  • Sail

if (%%LINK%func;implemented?;implemented?%%(ExtensionName::B) && (%%LINK%csr_field;misa.B;CSR[misa].B%% == 1'b0)) {
  %%LINK%func;raise;raise%%(ExceptionCode::IllegalInstruction, %%LINK%func;mode;mode%%(), $encoding);
}
XReg shamt = (%%LINK%func;xlen;xlen%%() == 32) ? X[rs2][4:0] : X[rs2][5:0];
X[rd] = (X[rs1] >> shamt) | (X[rs1] << (%%LINK%func;xlen;xlen%%() - shamt));
{
  let rs1_val = X(rs1);
  let rs2_val = X(rs2);
  let result : xlenbits = match op {
    RISCV_ANDN => rs1_val & ~(rs2_val),
    RISCV_ORN  => rs1_val | ~(rs2_val),
    RISCV_XNOR => ~(rs1_val ^ rs2_val),
    RISCV_MAX  => to_bits(sizeof(xlen), max(signed(rs1_val),   signed(rs2_val))),
    RISCV_MAXU => to_bits(sizeof(xlen), max(unsigned(rs1_val), unsigned(rs2_val))),
    RISCV_MIN  => to_bits(sizeof(xlen), min(signed(rs1_val),   signed(rs2_val))),
    RISCV_MINU => to_bits(sizeof(xlen), min(unsigned(rs1_val), unsigned(rs2_val))),
    RISCV_ROL  => if sizeof(xlen) == 32
                  then rs1_val <<< rs2_val[4..0]
                  else rs1_val <<< rs2_val[5..0],
    RISCV_ROR  => if sizeof(xlen) == 32
                  then rs1_val >>> rs2_val[4..0]
                  else rs1_val >>> rs2_val[5..0]
  };
  X(rd) = result;
  RETIRE_SUCCESS
}

Exceptions

This instruction may result in the following synchronous exceptions:

  • IllegalInstruction