bs - 2024.2 English

Description

Shifts the contents of register rA by the amount specified in register rB and puts the result in register rD.

The mnemonic bsll sets the S bit (Side bit). If the S bit is set, the barrel shift is done to the left. The mnemonics bsrl and bsra clear the S bit and the shift is done to the right.

The mnemonic bsra will set the T bit (Type bit). If the T bit is set, the barrel shift performed is Arithmetical. The mnemonics bsrl and bsll clear the T bit and the shift performed is Logical.

Pseudocode

if S = 1 then
   (rD) ← (rA) << (rB)[27:31]
else
   if T = 1 then
      if ((rB)[27:31]) ≠ 0 then
         (rD)[0:(rB)[27:31]-1] ← (rA)[0]
         (rD)[(rB)[27:31]:31] ← (rA) >> (rB)[27:31]
      else
         (rD) ← (rA)
   else
      (rD) ← (rA) >> (rB)[27:31]

Registers Altered

• rD

Latency

• 1 cycle with C_AREA_OPTIMIZED=0 or 2
• 2 cycles with C_AREA_OPTIMIZED=1

Note

These instructions are optional. To use them, MicroBlaze has to be configured to use barrel shift instructions (C_USE_BARREL=1).