- /*
- * Okay lets designate what the hell is an acceptable use
- * of the ^ operator. In many vector processing units, XOR
- * is allowed to be used on vectors, but only if the first
- * operand is a vector, the second operand can be a float
- * or vector. It's never legal for the first operand to be
- * a float, and then the following operand to be a vector.
- * Further more, the only time it is legal to do XOR otherwise
- * is when both operand are floats. This nicely crafted if
- * statement catches them all.
- *
- * In the event that the first operand is a vector, two
- * possible situations can arise, thus, each element of
- * vector A (operand A) is exclusive-ORed with the corresponding
- * element of vector B (operand B), If B is scalar, the
- * scalar value is first replicated for each element.
- *
- * The QCVM itself lacks a BITXOR instruction. Thus emulating
- * the mathematics of it is required. The following equation
- * is used: (LHS | RHS) & ~(LHS & RHS). However, due to the
- * QCVM also lacking a BITNEG instruction, we need to emulate
- * ~FOO with -1 - FOO, the whole process becoming this nicely
- * crafted expression: (LHS | RHS) & (-1 - (LHS & RHS)).
- *
- * When A is not scalar, this process is repeated for all
- * components of vector A with the value in operand B,
- * only if operand B is scalar. When A is not scalar, and B
- * is also not scalar, this process is repeated for all
- * components of the vector A with the components of vector B.
- * Finally when A is scalar and B is scalar, this process is
- * simply used once for A and B being LHS and RHS respectfully.
- *
- * Yes the semantics are a bit strange (no pun intended).
- * But then again BITXOR is strange itself, consdering it's
- * commutative, assocative, and elements of the BITXOR operation
- * are their own inverse.
- */