Completes 65816 addressing mode tests and corresponding fixes.

Processors/65816/Implementation/65816Implementation.hpp

@@ -360,8 +360,9 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
 			continue;
 
 			case OperationConstructStackRelativeIndexedIndirect:
-				data_address_ = (instruction_buffer_.value + y()) & 0xffff;
+				data_address_ = data_bank_ + data_buffer_.value + y();
 				data_address_increment_mask_ = 0xff'ff'ff;
+				data_buffer_.clear();
 			continue;
 
 			case OperationConstructPER:

Processors/65816/Implementation/65816Storage.hpp

@@ -325,6 +325,7 @@ struct ProcessorStorage {
 
 		private:
 			uint8_t *byte(int pointer) {
+				assert(pointer >= 0 && pointer < 4);
 				#if TARGET_RT_BIG_ENDIAN
 					return reinterpret_cast<uint8_t *>(&value) + (3 ^ pointer);
 				#else