lbzepx

Load Byte and Zero External Process ID Indexed

lbzepx RT, RA, RB

Loads a byte using the External PID (for OS kernels accessing user memory).

Details

Loads a byte from memory using the External Process ID (EPID), which allows privileged code to access memory belonging to an external process. The effective address is computed from RA and RB, and the loaded byte is zero-extended into the target GPR. This is an embedded/privileged instruction used by operating system kernels.

Pseudocode Operation

EA ← (RA = 0 ? 0 : GPR[RA]) + GPR[RB]
GPR[RT] ← (0)56 || [EA]8

Example

lbzepx r3, r4, r5

Encoding

Binary Layout
31
0
RT
6
RA
11
RB
16
31
21
/
31
 
Format X-form
Opcode 0x7C00003E
Extension Embedded

Operands

  • RT
    Target
  • RA
    Base
  • RB
    Index