sh1add

Shift left by 1 and add

This instruction is defined by:

  • Zba, version >= Zba@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

svg

Assembly format

sh1add rd, rs1, rs2

Synopsis

This instruction shifts rs1 to the left by 1 bit and adds it to 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);
}
X[rd] = X[rs2] + (X[rs1] << 1);
{
  let rs1_val = X(rs1);
  let rs2_val = X(rs2);
  let shamt : bits(2) = match op {
    RISCV_SH1ADD => 0b01,
    RISCV_SH2ADD => 0b10,
    RISCV_SH3ADD => 0b11
  };
  let result : xlenbits = (rs1_val << shamt) + rs2_val;
  X(rd) = result;
  RETIRE_SUCCESS
}

Exceptions

This instruction may result in the following synchronous exceptions:

  • IllegalInstruction