popcntb

Population Count Bytes

popcntb RA,RS

Counts the number of one bits in each byte of a register.

Details

A count of the number of one bits in each byte of register RS is placed into the corresponding byte of register RA. This number ranges from 0 to 8, inclusive.

Pseudocode Operation

for i = 0 to 7
    n ← 0
    for j = 0 to 7
        if (RS)(i×8)+j = 1 then
            n ← n+1
    RA(i×8):(i×8)+7 ← n

Programming Note

None

Example

popcntb r4, r3

Encoding

Binary Layout
0
0
RS
6
RA
11
6
16
11
21
16
31
21
31
 
Format X-form
Opcode 0x7C0000F4
Extension Base

Operands

  • RA
    Target General Purpose Register
  • RS
    Source General Purpose Register