fsub.s

No synopsis available.

This instruction is defined by:

  • F, version >= 0

This instruction is included in the following profiles:

  • RVA20U64 (Mandatory)

  • RVA22U64 (Mandatory)

  • RVI20U32 (Optional)

  • RVI20U64 (Optional)

Encoding

svg

Assembly format

fsub.s fd, fs1, fs2, rm

Synopsis

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

No description available.

Access

M HS U VS VU

Always

Always

Always

Always

Always

Decode Variables

Bits<5> fs2 = $encoding[24:20];
Bits<5> fs1 = $encoding[19:15];
Bits<3> rm = $encoding[14:12];
Bits<5> fd = $encoding[11:7];

Execution

  • IDL

  • Sail

{
  let rs1_val_32b = F_or_X_S(rs1);
  let rs2_val_32b = F_or_X_S(rs2);
  match (select_instr_or_fcsr_rm (rm)) {
    None() => { handle_illegal(); RETIRE_FAIL },
    Some(rm') => {
      let rm_3b = encdec_rounding_mode(rm');
      let (fflags, rd_val_32b) : (bits(5), bits(32)) = match op {
        FADD_S  => riscv_f32Add (rm_3b, rs1_val_32b, rs2_val_32b),
        FSUB_S  => riscv_f32Sub (rm_3b, rs1_val_32b, rs2_val_32b),
        FMUL_S  => riscv_f32Mul (rm_3b, rs1_val_32b, rs2_val_32b),
        FDIV_S  => riscv_f32Div (rm_3b, rs1_val_32b, rs2_val_32b)
      };
      accrue_fflags(fflags);
      F_or_X_S(rd) = rd_val_32b;
      RETIRE_SUCCESS
    }
  }
}