MIPS to C Translation

c assembly mips translate
user2789564 picture user2789564 · Sep 19, 2013 · Viewed 14.2k times · Source

I need to translate some MIPS assembly instructions to C code. I think I got it, but it seems counter-intuitive. Any help? We have variables f, g, h, i, j stored in registers $s0, $s1, $s2, $s3 and $s4 respectively. The base of arrays A and B are stored in $s6 and $s7 respectively. 4 byte words. Comments in the code are my own. 

addi $t0, $s6, 4   # $t0 = A[1]
add $t1, $s6, $0   # $t1 = A[0]
sw $t1, 0($t0)     # $t0 = A[0]
lw $t0, 0($t0)     # $t0 = A[0]
add $s0, $t1, $t0  # f = A[0] + A[0]

I just feel like I'm wrong. Why make $t0 A[1] first if we never use it?

Answer

TheCyberliem picture TheCyberliem · Jun 17, 2016

I think you have got in completely wrong.

addi $t0, $s6, 4 # $t0 = A[1]

After the addi, register $t0 became the memory address of A[1], which would be &A[1], not A[1]. To get value of A[1], you need to use lw after you done the addi

lw $t0, 0($t0) # $t0 =A[1]

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