Converting signed hex integer to display negative decimal integer on terminal in C code

Question

I am trying to take a signed hex number and display it on the terminal as a negative decimal number so that it can be easily read. I am having a hard time working through the logic on how to make this happen. I am using a PIC16F15345 and Real Term as my terminal. My UART is up and running correctly.

Problem Example:

Hex: B6

Display dec value: -74

I have thought about first converting the hex number to binary by creating a large if statement for each byte and then concatenate them together, but I am not quite sure on where to go next for converting to decimal. I need this code to be efficient and easily readable as it is going into some documentation I have and all of my ideas seem very complex and long. I feel like I am overthinking this.

Thank you for the help

Answer 1

no conversion is needed, just cast it to signed, then proceed normally.

Answer 2

There are signed and unsigned variables. 1st) you need to declare signed variable of 8-bit size. If it doesn't exist then you may declare as signed variable of 16bit (or whatever bit value the PIC is made). The MSB bit is a sign bit, so how to make you 8 bit number to get the sign? You do shift left for 8 places and then do arithmetic shift right to 8 places back. With arithmetic shift the sign is preserved. Then use Printf function with the right format.