Question

Write a function (subroutine) that inputs a data value in register r0 and returns value in r0. The function returns y 5 a 1 bx 1 cx2, where a, b, and c are parameters built into the function (i.e., they are not passed to it). The subroutine also performs clipping. If the output is greater than a value d, it is constrained to d (clipped). The input in r0 is a positive binary value in the range 0 to 0xFF. Apart from r0, no other registers may be modified by this subroutine. Write ARM code to implement the following C operation.

Int s=0;
for ( i = 0; i < 10; i++) { s = s + i*i;)

Answer 1

int f(int x){

`\text{return a + b*x +c*x*x}`;

}*/

int f(
`\text{int R0}`){

int stack[2] = {
`\text{R1,R2}`};

`\text{R1 = R0}`;

`\text{R1 = R1}* \text{ R1}`;

`\text{R2 = C}`;

R1 = R1 * C; /*R1 =
`cx^2`*/

`\text{R2 = B}`;

`\text{R0 = R0}` * R2; /* R0 = bx */

`\text{R0 = R0 + R1}`; /*R0 =
`bx + cx^2` */

`\text{R2 = C}`;

`\text{R0 = R0 + R2}`; /*R0 = a+bx+cx^2 */

`\text{R1 = stack[0];}`

`\text{ R2 = stack[1];}`

`\text{ return R0;}`

}

/*
`\text{ARM code to implement the following C operation}`

int s=0;

`\text{for ( i = 0; i < 10; i++)}`

{
`\text{s = s + i } * i`;)

*/

AREA SumSquares, code, readWrite

ENTRY

`\text{MOV r0, #0}` ;loop
`\text{ counter i present at 0}`

MOV r1, #0 ; s = 0

Loop
`\text{MUL r2, r0, r0}` ;calculate i*i

`\text{ADD r1, r1, r2}` ;s = s+ i*i

`\text{ADDS r0, r0}`, #1 ; i = i+1

`\text{CMP r0}`,#10 ; test for end

`\text{BNE}` Loop ;
`\text{continue until all added}`

END