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HW2 solution

  1. (20 points) Convert the following C code to RISC-V assembly instructions. Use the minimum number of instructions necessary. Assume that variables f, g and h are 32- bit integers stored in registers x5, x6 and x7 respectively and that the base address of arrays A and B are in registers x8 and x9 respectively. A and B are arrays of 4-byte integers (this is important).

    Be careful not to modify the variables unintentionally. If you need to store temporary values, use one of the other registers.

    a. f = g + h;

    add x5, x6, x7

    b. f = g - (h - 5);

    addi x5, x7, -5
sub  x5, x6, x5

    c. Remember, the elements of A are 4-bytes big!
    f = A[3] - g;

    lw   x5, 12(x8)
sub  x5, x5, x6

    d. A[0] = f + B[1];

    lw   x10, 4(x9)
add  x10, x10, x5
sw   x10, 0(x8)