Question

Registers in RISC-V are 64-bit. For the sake of simplicity, consider the following instructions operating on 32-bit registers. Assume that registers x5 and x6 hold the values 0xEEEEEEEE and 0x00000000, respectively.

• (2 points) – What is the value in x6 for the following slli x6, x5, 6

• (2 points) – Using the result from the part above, what is the value in x6 for the following instruction. srli x6, x6, 6

Answer 1

slli: instruction will perform a logical left shift of the contents of register x5 and stores the shifted value in register x6. The shift amount is taken from the 5-bit immediate field,i.e 6. The value 0 is shifted in from the right to replace lost bits

slli x6, x5, 6

x5 will hold the value 0xBBBB BB80‬

srli: instruction will perform a logical right shift of the contents of register x6 and stores the shifted value in register x6. The shift amount is taken from the 5-bit immediate field,i.e 6. The value 0 is shifted in from the left to replace lost bits .

srli x6, x6, 6

x6 will hold 0x02EEEEEE