remuw

Unsigned 32-bit remainder

Calculate the remainder of unsigned division of the 32-bit values in xs1 by xs2, and store the sign-extended result in xd.

If the value in xs2 is zero, xd gets the sign-extended value in xs1.

Assembly format

remuw rd, rs1, rs2

Decode Variables

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

Execution

  • IDL

  • Sail

if (implemented?(ExtensionName::M) && (misa.M == 1'b0)) {
  raise(ExceptionCode::IllegalInstruction, mode(), $encoding);
}
Bits<32> src1 = X[xs1][31:0];
Bits<32> src2 = X[xs2][31:0];
if (src2 == 0) {
  Bits<1> sign_bit = src1[31];
  X[xd] = {{32{sign_bit}}, src1};
} else {
  Bits<32> result = src1 % src2;
  Bits<1> sign_bit = result[31];
  X[xd] = {{32{sign_bit}}, result};
}
{
  if extension("M") then {
    let rs1_val = X(rs1)[31..0];
    let rs2_val = X(rs2)[31..0];
    let rs1_int : int = if s then signed(rs1_val) else unsigned(rs1_val);
    let rs2_int : int = if s then signed(rs2_val) else unsigned(rs2_val);
    let r : int = if rs2_int == 0 then rs1_int else rem_round_zero(rs1_int, rs2_int);
    /* signed overflow case returns zero naturally as required due to -1 divisor */
    X(rd) = sign_extend(to_bits(32, r));
    RETIRE_SUCCESS
  } else {
    handle_illegal();
    RETIRE_FAIL
  }
}

Exceptions

This instruction may result in the following synchronous exceptions:

  • IllegalInstruction

Encoding

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Defining extension

M, version >= M@2.0.0

Access

M

Always

Containing profiles

  • Mandatory: RVA20S64, RVA20U64, RVA22S64, RVA22U64, RVA23M64, RVA23S64, RVA23U64, RVB23M64, RVB23S64, RVB23U64

  • Optional: RVI20U32, RVI20U64