sext.b

Sign-extend byte

This instruction is defined by:

Encoding

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Synopsis

Sign-extends the least-significant byte in the source to XLEN by copying the most-significant bit in the byte (i.e., bit 7) to all of the more-significant bits.

Access

M HS U VS VU

Always

Always

Always

Always

Always

Decode Variables

Bits<5> xs1 = $encoding[19:15];
Bits<5> xd = $encoding[11:7];

Execution

  • Pruned, XLEN == 64

  • Original

X[xd] = {{56{X[xs1][7]}}, X[xs1][7:0]};
if (xlen() == 32) {
  X[xd] = {{24{X[xs1][7]}}, X[xs1][7:0]};
} else if (xlen() == 64) {
  X[xd] = {{56{X[xs1][7]}}, X[xs1][7:0]};
}