rem: r3 = eqv(d,r2);
add: r3 = ~(d^r2);
context: static u32 exnor_1st(u32 a,u32 b){	u32 c,d,e,f,r1,r2,r3,r4;	c = 0;	while(c<b) {		d = (a>>23);		e = (a>>15);		f = (a>>7);		r1 = (a^f);		r2 = (e^r1);		r3 = eqv(d,r2);		e = (a>>1);		r4 = ((r3<<30)&0x40000000);		a = (e|r4);		c++;	};	return a;}