bset

Single-Bit set (Register)

This instruction is defined by:

Encoding

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Synopsis

This instruction returns rs1 with a single bit set at the index specified in rs2. The index is read from the lower log2(XLEN) bits of 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

  • Pruned, XLEN == 64

  • Original

XReg index = X[rs2] & (63);
X[rd] = X[rs1] | (1 << index);
if (implemented?(ExtensionName::B) && (CSR[misa].B == 1'b0)) {
  raise(ExceptionCode::IllegalInstruction, mode(), $encoding);
}
XReg index = X[rs2] & (xlen() - 1);
X[rd] = X[rs1] | (1 << index);