crc32b

Cyclic Redundancy Check 32-bit Byte

crc32b RA, RS

Accumulates a CRC32 checksum using the low byte of RS.

Details

Accumulates a 32-bit CRC checksum using the low byte (bits 56–63) of RS, with the running CRC value in RA. The updated CRC result is written to RA. This is a Base-category instruction with no CR, XER, or FPSCR updates.

Pseudocode Operation

byte_val ← RS[56:63]; crc ← RA ⊕ (byte_val || [0]*24); for i in 0 to 7 do; if (crc[31] = 1) then crc ← (crc << 1) ⊕ 0x04C11DB7; else crc ← crc << 1; crc ← crc ∧ 0xFFFFFFFF; RA ← crc;

Example

crc32b r4, r3

Encoding

Binary Layout
31
0
RS
6
RA
11
0
16
522
21
/
31
 
Format X-form
Opcode 0x7C00020A
Extension Base

Operands

  • RA
    Target/Accumulator
  • RS
    Data