SHR : logic SHift Right (divide unsigned by a power of two)

The bits of the source register (snd) are shifted towards the LSB, by a number of bits indicated either by

• a 4-bit immediate value (short immediate or extended immediate forms)
• the other register (si4) (short register or extended register forms)
• a 16-bit value (long immediate form).

The MSB of the result are filled with 0s for this logic shift, while the arithmetic shift (SAR) fills the MSB with the value of the original MSB.