CareerCup

{
char a;//the input variable
char b;// the output variable
int X=sizeof(a)*tot_siz;
b=a;
a>>=1;
while(a){
b|=a&1;
b<<=1;
a>>=1;
X--
}
b<<=X;
}

i think this should work..but then he asked me optimize the code further..i said you could use bit masking techniques in a look up format like 0x5555 and 0x3333 types...he then said there's a better way to get this done... am i missing something?

Use a look up table. Store reversed bytes(obtained from a similar function as yours) in an array. Then reverse of number n would be array[n]

algo:-
(1)Anding the given no with 1,will give LSB.push it on stack.
(2)Right shift the no by 1.goto the step 1
(3)repeat step 1 and 2 until no become 0.
(4)when no become 0 pop bits from the stack.
write the code urself.........

bitRev(char *p, int tot_size){

char *q;
int swapEle;

q = p+tot_size;

while(p<q){
swapEle = *p;
*p = *q;
*q = swapEle;
}
}