=IF(A1=0,0,B1/A1)

What I would like it to do is that if B1 & A1 are both 0, then answer should be 0. If A1 has a value that is not 0, then use B1/A1. This can be resolved by my current formula

The next bit is the tricky bit. If A1 is 0 and B1 is greater than zero, the answer is 1, if B1 is less than 0, the answer is -1.

Please help