lbu

Load byte unsigned

Load 8 bits of data into register xd from an address formed by adding xs1 to a signed offset. Zero extend the result.

Assembly format

lbu xd, imm(xs1)

Decode Variables

signed Bits<12> imm = sext($encoding[31:20], 12);
Bits<5> xs1 = $encoding[19:15];
Bits<5> xd = $encoding[11:7];

Execution

XReg virtual_address = X[xs1] + $signed(imm);
X[xd] = read_memory(8, virtual_address, $encoding);

Exceptions

This instruction may result in the following synchronous exceptions:

  • LoadAccessFault

  • LoadAddressMisaligned

  • LoadPageFault

Encoding

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Defining extension

I

Access

M

Always

Containing profiles

  • Mandatory: RVA20S64, RVA20U64, RVA22S64, RVA22U64, RVA23S64, RVA23U64, RVB23S64, RVB23U64, RVI20U32, RVI20U64

  • Optional: None