lbzu

Load Byte and Zero with Update D-form

lbzu RT,D(RA)

Loads a byte from memory into a register, zeroing the upper bits of the target register, and updates the base address register.

Details

The effective address (EA) is calculated as the sum of the contents of register RA and the sign-extended displacement D. The byte at EA is loaded into RT56:63, with RT0:55 set to zero. The EA is then stored back into RA.

Pseudocode Operation

EA ← (RA) + EXTS(D)
RT ← 560 || MEM(EA, 1)
RA ← EA

Programming Note

The base register (RA) is updated with the effective address after the memory access. RA must not be 0 and must differ from the destination register; violating this constraint produces undefined results.

Example

lbzu r3, 0(r4)

Encoding

Binary Layout
0
0
RT
6
RA
11
D
16
 
Format D-form
Opcode 0x8C000000
Extension Base

Operands

  • RT
    Target General Purpose Register
  • RA
    Base Address General Purpose Register
  • D
    Displacement