Concatenate 2 16 bit words into one 16 bit word in c

Question

I am trying to get the Least significant 4 bits of one word and the most significant 12 bits of another word and concatenate them into a single word. I am working in C, which I haven't worked with much in the past.

int a;
int b;
int c;
int a_masked;
int b_masked;
a = 0x1234;
b = 0xABCD;

a_masked = a & 0X000F;
b_masked = b & 0xFFF0;

c = ((a_masked << 12) || b_masked >> 4);

printf("%d", c);

C should be 4ABC, but my result is 1.

Note: `%x` and `%X` will print an `int` in hexadecimal, which will make it easier to see if your bitwise operation succeeded. — Govind Parmar, Mar 18 '21 at 20:28
Apart from the `||`, watch it when shifting _signed_ values (i.e. probably don't do that): https://stackoverflow.com/q/7622/6372809 — ilkkachu, Mar 18 '21 at 21:18

score 3 · Accepted Answer · answered Mar 18 '21 at 20:18

3

|| operator, which you used, is a logical OR operator and it returns 0 or 1.

You should use a bitwise OR operator | (one vertical line, not two).

answered Mar 18 '21 at 20:18

MikeCAT

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Concatenate 2 16 bit words into one 16 bit word in c

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