cbit-manipulation

Extracting the first 3 bits of an uint8

A struct I'm dealing with has a field defined as uint8_t. The spec also states that all multiple-byte fields are represented in host-endian format.

Bits 0:3 contain the information that I need (also an unsigned integer). Using plain C, how do I extract those 3 bits and convert it to a number type?

Solution 
  • unit8_t a;
unit8_t b;

a = input data;

b = a & 0x0F;       // b contains a number from 0 to 15