c.srai

Shift right arithmetical immediate

This instruction is defined by:

anyOf:
- C, version >= 0
- Zca, version >= 0

This instruction is included in the following profiles:

Encoding

Assembly format

c.srai rd, shamt

Synopsis

Arithmetic shift (the original sign bit is copied into the vacated upper bits) the value in rd right by shamt, and store the result in rd. The rd register index should be used as rd+8 (registers x8-x15). C.SRAI expands into srai rd, rd, shamt.

Access

M	HS	U	VS	VU
Always	Always	Always	Always	Always

Always

Decode Variables

Bits<6> shamt = {$encoding[12], $encoding[6:2]};
Bits<3> rd = $encoding[9:7];

Execution

IDL
Sail

X[rd + 8] = X[rd + 8] >>> shamt;

{
  let rd_val = X(rd+8);
  /* the decoder guard should ensure that shamt[5] = 0 for RV32 */
  let result : xlenbits = match op {
    RISCV_SLLI => if   sizeof(xlen) == 32
                  then rd_val << shamt[4..0]
                  else rd_val << shamt,
    RISCV_SRLI => if   sizeof(xlen) == 32
                  then rd_val >> shamt[4..0]
                  else rd_val >> shamt,
    RISCV_SRAI => if   sizeof(xlen) == 32
                  then shift_right_arith32(rd_val, shamt[4..0])
                  else shift_right_arith64(rd_val, shamt)
  };
  X(rd+8) = result;
  RETIRE_SUCCESS
}