struct line {
	char block[16];
	unsigned tag;
	bool valid;
}

line cache[4];

bool isInCache(unsigned address) {
	// address 10987654321098765432109876[54][3210]
	//                                        block offset
	//                                    set index 
	//          the rest of the address
	
	unsigned setIndex = (address>>4)&3;
	unsigned blockOffset = address&0xf;
	unsigned tag = address >> 6;
	line inQuestion = cache[setIndex];
	return tag == line.tag;
}

bool readByte(unsigned address) {
	// address 10987654321098765432109876[54][3210]
	//                                        block offset
	//                                    set index 
	//          the rest of the address
	
	unsigned setIndex = (address>>4)&3;
	unsigned blockOffset = address&0xf;
	unsigned tag = address >> 6;
	line inQuestion = cache[setIndex];
	if (tag == inQuestion.tag && inQuestion.valid) {
		return inQuestion.block[blockOffset];
	} else {
		char read[16] = lineFromMemory(address);
		cache[setIndex].tag = tag;
		cache[setIndex].block = read; // not valid C
		cache[setIndex].valid = 1;
		return inQuestion.block[blockOffset];
	}
}