Question

Write C code that perform the same as the assembly code. Hint:data is an integer avariable in C. OUT is a name of a function:- //code part is the following..

L1 LDR R0, =0X006 ;The hexadecimal of 0110 is 0x006

L2 LDR R1, =data

L3 LDR R2, [data]

L4 AND R2, #0X006

L5 CMP R2, #0X006

L6 BLEQ OUT

L7 ..................

Answer 1

Lets understand what each instruction is doing.

L1 LDR R0, =0X006   //Load into R0 the value 6

L2 LDR R1, =data    //Load into R1 the value of data

L3 LDR R2, [data] //load into R2, the address of variable data

L4 AND R2, #0X006 //Perform AND operation of R2 with value 6 and store in R2

L5 CMP R2, #0X006 //compare the content of R2 and 0x006

L6 BLEQ OUT   //If content of R2 is less than or equal to 6 then call the function at address OUT.

Below is the equivalent C code:-

int a,b,*c;

a = 6; //load value 6 into variable a

b = data;   //load the value of data in b

c = &data; //load the address of variable data into point c

c = c & 6; //perform bitwise AND operation of pointer c with 6

if( c <= 6)

OUT();    //call the function OUT if c is <= 6

Please comment for any clarification.