Question

1. Show the single MIPS instruction or minimal sequence of instructions for the following C statement: X[10]=X[11]+L; Assume the L corresponds to register $t0 and the array X has a base address of 0x003D0900.

Answer 1

The MIPS instructions for the C statement 'X[10]=X[11]+L;' where L is in register $t0 and the base address of array X is 0x003D0900 are: loading the value at X[11], adding the value in $t0, and storing the result in X[10], assuming prior setup of the base address in a register, likely $t2.

Step-by-step explanation:

The question asks for a MIPS assembly language translation of the C code X[10]=X[11]+L; given that L is in register $t0 and the base address of the array X is 0x003D0900. To perform this operation in MIPS, we need to follow these steps:

• Load the value at X[11] into a register.
• Add the value of L from register $t0 to this register.
• Store the result back into the address corresponding to X[10].

Here's the MIPS instruction sequence to achieve the above operations:

1. lw $t1, 44($t2) ; Load word from X[11], $t2 should have the base address of X.
2. add $t1, $t1, $t0 ; Add L(in $t0) to the value from X[11].
3. sw $t1, 40($t2) ; Store the result back into X[10].

We assume that prior instructions have loaded the base address of X into $t2. Each element of the array X is assumed to be 4 bytes (a word) since we are using load word (lw) and store word (sw) instructions. Thus, the offset for X[11] is 11*4 = 44 bytes, and the offset for X[10] is 10*4 = 40 bytes.