lb

Load byte

This instruction is defined by:

Encoding

svg

Synopsis

Load 8 bits of data into register rd from an address formed by adding rs1 to a signed offset. Sign extend the result.

Access

M

HS

U

VS

VU

Always

Always

Always

Always

Always

Decode Variables

Bits<12> imm = $encoding[31:20];
Bits<5> rs1 = $encoding[19:15];
Bits<5> rd = $encoding[11:7];

Execution

  • Pruned, XLEN == 64

  • Original

XReg virtual_address = X[rs1] + imm;
X[rd] = sext(read_memory<8>(virtual_address, $encoding), 8);
XReg virtual_address = X[rs1] + imm;
X[rd] = sext(read_memory<8>(virtual_address, $encoding), 8);

Exceptions

This instruction may result in the following synchronous exceptions:

  • LoadAccessFault

  • LoadPageFault