Name: Date:

HW6

  1. You are writing a RISC-V assembly program. Your program has a beq instruction at address 0x0100 0400. You wish this beq to branch to location 0x0200 0000.

    1. (3 points) How close a single beq instruction get to the goal address? Express your answer as the address nearest to the target address as possible.
    1. (3 points) What is a possible method to allow long-range conditional branches?

  2. You are writing a program for a processor with 8-bit instructions. The branch instructions for this processor only allow 3-bit branch immediate.

    1. (3 points) Assuming the immediate is sign extended, what is the branch range of the processor? Answer in byte units.
    1. (3 points) What is the difficulty with such a branch range? Write out a simple while loop example to illustrate the difficulty.

  1. Compute the correct hex value for the branch targets below, give your answers in the correct number of digits in hexidecimal, including any leading zeros.

    Address Instruction
    0x00400028 
          jal x0, test
    0x0040002c 
    loop: lw   t1, 0(t2)
    0x00400030 
          addi t3, t3, -4
    0x00400034 
    test: bne  t1, x0, loop
    1. (3 points) List both the byte offset and immediate used by the jal instruction? Show your work.
    1. (3 points) What is the hex value for the immediate in the bne instruction? Show your work.