Please explain this bit-wise operation line by line

/* * * * * * * rotateLeft Rotate x to the left by n Can assume that 0 > Max ops: 25 * Rating: 3 */ int rotateLeft(int x, int n) { int y = (1 n) + ~0; int x1 = (x >> (33 + ~n)) & y; return (x n) | x1; }