Write out the Truth Table for XOR
In1 In2 AND NAND XOR XNOR XOR
0 0 0 1 0 1 low if x==0 and y==0
0 1 0 1 1 0 high if x !=y
1 0 0 1 1 0 high if x !=y
1 1 1 0 0 1 low of x==1 and y==1
Do the same for 3 inputs:
low if x==0 and y==0 and z==0
high if x==0 and y==0 and z==1 only 1 input high
high if x==0 and y==1 and z==0 only 1 input high
low if x==0 and y==1 and z==1
high if x==1 and y==0 and z==0 only 1 input high
low if x==1 and y==0 and z==1
low if x==1 and y==1 and z==0
low if x==1 and y==1 and z==1
Am sure you can find ways to reduce this some
Or maybe make an array
if (XOR[xyz] == 1){
// true for 001, 010, 100
}