I have an uint8_t and I need to read/write to specific bits. How would I go about doing this. Specifically what I mean is that I need to write and then later read the first 7 bits for one value and the last bit for another value.
edit: forgot to specify, I will be setting these as big endian
You're looking for bitmasking. Learning how to use C's bitwise operators: ~, |, &, ^ and so on will be of huge help, and I recommend you look them up.
Otherwise -- want to read off the least significant bit?
uint8_t i = 0x03;
uint8_t j = i & 1; // j is now 1, since i is odd (LSB set)
and set it?
uint8_t i = 0x02;
uint8_t j = 0x01;
i |= (j & 1); // get LSB only of j; i is now 0x03
Want to set the seven most significant bits of i to the seven most significant bits of j?
uint8_t j = 24; // or whatever value
uint8_t i = j & ~(1); // in other words, the inverse of 1, or all bits but 1 set
Want to read off these bits of i?
i & ~(1);
Want to read the Nth (indexing from zero, where 0 is the LSB) bit of i?
i & (1 << N);
and set it?
i |= (1 << N); // or-equals; no effect if bit is already set
These tricks will come in pretty handy as you learn C.