ECE 232: Homework # 3
Due March 1
Compile your code in SPIM and verify your answers. Your codes should contain
appropriate assembler directives. SPIM is available at
http://pages.cs.wisc.edu/~larus/spim.html
1.
[10 pts] What is the difference between pseudo instruction and real
instruction? Can a MIPS machine execute pseudo instructions? Consider a
pseudo instruction: la $rs, addr, which loads the 32-bit address addr into
register $rs. Implement this instruction with real MIPS instructions.
2.
[10 pts] Assume that the address of a[0], b[0], and c[0] are in registers $s0,
$s1 and $s2. i is in $s3 and j is in $s4. Translate the following into MIPS
assembly code:
j=0;
for (i = 10; i >= 2; i--) {
a[i] = 2*b[i] + c[i] - 5;
j = j + a[i];
}
3.
[10 pts] Translate the following into MIPS assembly code:
if (i < 6)
j = j
else if (i
j = j
else
j = j
+ 8;
== 6)
- 7;
/ 3;
Assume that variable i is in register $s0 and j is in register $s1.
4. [15 pts] Translate the following into MIPS assembly code
i=0;
while ((a[i] >= 15) && (i < 12)) {
i = i+3;
b[i] = b[i] - a[i];
}
Assume that the memory address of a[0] is in register $s0 and that of b[0] is in
register $s1. Assume i is in register $s3.
5. [10 pts] Translate the following into MIPS assembly code
switch (i) {
case 0: j = 5; break;
case 1: ;
case 2: j = 9; break;
case 3: j = 3; break;
case 4: j = 11; break;
default: j = 7;
}
Assume i is in $s1 and j is in $s2;
6.
[15 pts] This question deals with matrix multiplication:
for (i=0; i<n; i++) {
for (j=0; j<n; j++) {
for (k=0; k<n; k++) {
c[i][j] = c[i][j] + a[i][k]*b[k][j];
}
}
}
For multiplication, use mult instruction, not the pseudo-instruction mul. You
can assume that the numbers involved are small enough that the results of
each multiplication can be held in just 32 bits. Assume that the addresses of
a[0][0], b[0][0], and c[0][0] are held in registers $t1, $t2 and $t3,
respectively. Assume i, j, and k are stored in $s1, $s2, and $s3, respectively.
Each matrix is stored in row-major order, i.e., entries in the first row are
stored first, followed by the second row and so on. The value of n is stored in
register $s0.
Translate this into MIPS code and verify your answer. Use for
example, n=5, a[i][j]=i+n*j, b[i][j]=1.
7.
[20 pts] Translate the following code into MIPS code:
sum = 10;
for (i=0; i<n; i++)
if (isEven(i)) sum += i;
int isEven(int i)
return ( i & 1);
Assume sum is in $s1, i is in $t0, n is in $t1;
8.
[10 pts] Suppose the content of $s1 = 0x12344321. Then you execute the
instruction addi $s1, $s1, 0xdcba. What is the value of $s1 after
executing the addi instruction?