I'm trying to write a program that converts from decimal to base 4 using bit masking. First I wrote this program that converts from decimal to binary to understand how it works
#include <stdio.h>
void binary(unsigned int num) {
int i;
unsigned temp, mask=1;
mask<<=31;
for(i=0; i<32; i ) {
temp=num&mask;
printf("%d", temp>>(31-i));
mask>>=1;
}
}
int main () {
int n;
printf("Enter a number:\n");
scanf("%d", &n);
binary(n);
return 0;
}
Then I was trying to use the same approach here
void base4(unsigned int num) {
int i;
unsigned temp, mask=3;
mask<<=15;
for(i=0; i<16; i ) {
temp= // <<<==== ???
printf("%d", temp>>(15-i)*2);
mask>>=1;
}
I know that in in base 4, numbers use 2 bits. So if we are ANDing each bit of a given value lets say 22 with the corresponding bit of the mask=3
we will end up with something like this
.... 0 0 1 1 2 (base4)
.... 00 00 01 01 10 (bin)
I just couldn't use this information to apply it to my previous approach, would be great if someone could help.
CodePudding user response:
char *toBase4(char *buff, unsigned val, int printZeroes)
{
char *wrk = buff;
int shift = sizeof(val) * CHAR_BIT - 2;
unsigned mask = 3 << shift;
do
{
if((val & mask) || printZeroes)
{
*wrk = ((val & mask) >> shift) '0';
printZeroes = 1;
}
mask >>= 2;
}while((shift -= 2) >= 0);
*wrk = 0;
return buff;
}
int main(void)
{
char x[256];
printf("%s\n", toBase4(x, 0xff00, 0));
printf("%s\n", toBase4(x, 0xff00, 1));
}
CodePudding user response:
void base4(unsigned int num) {
int i;
unsigned int temp, mask=3;
mask<<=30;
for(i=0; i<16; i ) {
temp=num&mask;
printf("%d", temp>>(15-i)*2);
mask>>=2;
}
}