C :: Force Move In Checkers Game

I am doing a checkers program in C and were not allowed to use standard C99. Things are going relatively well so far. I have 2d array that acts as a matrix for my board and have ways to check if a space is empty and if it is occupied by a specific players chip.

Right now I have a giant messy method that I will split up sooner or later but Im just trying to understand and build the logic. It looks like this:

Code:
void isValidMove(int origin, int dest, int player) {
int rowDiff = abs(origin%8 - dest%8);
int possibleMoveLeftUp = origin - 9;
int possibleMoveLeftDown = origin + 9;
int possibleMoveRightUp = origin - 7;

[Code] ....

So although its not pretty i think the logic is sound. I can tell whether or not a player is attempting to make a move or a jump. I haven't implemented make_move() yet but thats no problems. My biggest deal is that I need to find a way to tell the user he has to jump if its available. I feel like this is a very difficult task for me to grasp and is more about algorithm logic and math then the C language which is what the course is for.

So, how I could loop through all of a specific players chips and see if that player has an available jump. Also if he does then the jump has to be taken and then checked again as if there is another legal jump then it needs to be taken as well until their are no jumps left. Of course there could be 2 routes available, but I think I could deal with that if I just could come up with a reasonable way of checking....