vrgather.vi

No synopsis available.

This instruction is defined by:

V, version >= 0

This instruction is included in the following profiles:

RVA22U64 (Optional)

Encoding

Assembly format

vrgather.vi vm, vs2, vd, imm

Synopsis

No description available.

Access

M	HS	U	VS	VU
Always	Always	Always	Always	Always

Always

Decode Variables

Bits<1> vm = $encoding[25];
Bits<5> vs2 = $encoding[24:20];
Bits<5> simm5 = $encoding[19:15];
Bits<5> vd = $encoding[11:7];

Execution

IDL
Sail

{
  let SEW_pow  = get_sew_pow();
  let SEW      = get_sew();
  let LMUL_pow = get_lmul_pow();
  let VLEN_pow = get_vlen_pow();
  let num_elem = get_num_elem(LMUL_pow, SEW);

  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };

  let 'n = num_elem;
  let 'm = SEW;

  let vm_val  : vector('n, dec, bool)     = read_vmask(num_elem, vm, 0b00000);
  let imm_val : nat                       = unsigned(zero_extend(sizeof(xlen), simm));
  let vs2_val : vector('n, dec, bits('m)) = read_vreg(num_elem, SEW, LMUL_pow, vs2);
  let vd_val  : vector('n, dec, bits('m)) = read_vreg(num_elem, SEW, LMUL_pow, vd);
  result      : vector('n, dec, bits('m)) = undefined;
  mask        : vector('n, dec, bool)     = undefined;

  (result, mask) = init_masked_result(num_elem, SEW, LMUL_pow, vd_val, vm_val);

  foreach (i from 0 to (num_elem - 1)) {
    if mask[i] then {
      result[i] = match funct6 {
        VI_VSLIDEUP    => {
                            if (vs2 == vd) then { handle_illegal(); return RETIRE_FAIL };
                            if i >= imm_val then vs2_val[i - imm_val] else vd_val[i]
                          },
        VI_VSLIDEDOWN  => {
                            let VLMAX = int_power(2, LMUL_pow + VLEN_pow - SEW_pow);
                            assert(VLMAX > 0 & VLMAX <= 'n);
                            if i + imm_val < VLMAX then vs2_val[i + imm_val] else zeros()
                          },
        VI_VRGATHER    => {
                            if (vs2 == vd) then { handle_illegal(); return RETIRE_FAIL };
                            let VLMAX = int_power(2, LMUL_pow + VLEN_pow - SEW_pow);
                            assert(VLMAX > 0 & VLMAX <= 'n);
                            if imm_val < VLMAX then vs2_val[imm_val] else zeros()
                          }
      }
    }
  };

  write_vreg(num_elem, SEW, LMUL_pow, vd, result);
  vstart = zeros();
  RETIRE_SUCCESS
}