prtyw

Parity Word

prtyw RA, RS

Calculates parity of a word (Scalar).

Details

The Parity Word instruction examines the least significant bit in each byte of the lower and upper halves of a doubleword (64 bits). It sets the corresponding output bytes to 1 if there is an odd number of one bits; otherwise, it sets them to 0.

Pseudocode Operation

s ← 0
t ← 0
do i = 0 to 3
    s ← s ⊕ (RS)i×8+7
do i = 4 to 7
    t ← t ⊕ (RS)i×8+7
RA0:31 ← 310 || s
RA32:63 ← 310 || t

Programming Note

The prtyw instruction is useful for calculating the parity of each byte in a doubleword, which can be helpful in error detection. Ensure that the input register (RS) contains valid data; otherwise, the output may not reflect meaningful parity information. This instruction operates at user privilege level and does not generate exceptions under normal conditions.

Example

prtyw r4, r3

Encoding

Binary Layout
31
0
RS
6
RA
11
/
16
154
21
/
31
 
Format X-form
Opcode 0x7C000128
Extension Base

Operands

  • RA
    Target
  • RS
    Source