lbzux

Load Byte and Zero with Update Indexed X-form

lbzux RT,RA,RB

Loads a byte from memory into a register, zero-extends it to 32 bits, and updates the base address.

Details

The sum of the contents of general-purpose register RA and the contents of general-purpose register RB is the effective address (EA). The byte in memory addressed by EA is loaded into the low-order 8 bits of general-purpose register RT, and the remaining bits of RT are cleared to 0. The effective address EA is placed into register RA. If RA = 0 or RA = RT, the instruction form is invalid.

Pseudocode Operation

EA ← (RA) + (RB)
RT ← 0x000000 || 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

lbzux r3, r4, r5

Encoding

Binary Layout
31
0
RT
6
RA
11
RB
16
119
21
/
31
 
Format X-form
Opcode 0x7C0000EE
Extension Base

Operands

  • RT
    Target General Purpose Register
  • RA
    Base Address General Purpose Register
  • RB
    Index General Purpose Register