amoor.b

Atomic fetch-and-or byte

Atomically:

  • Load the byte at address xs1

  • Write the sign-extended value into xd

  • OR the least-significant byte of register xs2 to the loaded value

  • Write the result to the address in xs1

Assembly format

amoor.b xd, xs2, (xs1)

Decode Variables

Bits<5> xs2 = $encoding[24:20];
Bits<5> xs1 = $encoding[19:15];
Bits<5> xd = $encoding[11:7];

Execution

XReg virtual_address = X[xs1];
X[xd] = sext(amo(8, virtual_address, X[xs2][7:0], AmoOperation::Or, 1'b0, 1'b0, $encoding), 8);

Exceptions

This instruction may result in the following synchronous exceptions:

  • LoadAccessFault

  • StoreAmoAccessFault

  • StoreAmoPageFault

Encoding

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Defining extension

Zabha

Access

M

Always

Containing profiles

  • Mandatory: None

  • Optional: RVA23U64, RVB23U64