From 327ab814367f394e1fdb06881ae1f95f5d7eb001 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 14 Oct 2020 21:17:28 -0400
Subject: [PATCH] Fills in direct, x and (direct) tests, fixing implementation
 of the latter.

10 to go.
---
 .../65816AddressingTests.swift                | 70 ++++++++++++++++++-
 .../Implementation/65816Implementation.hpp    |  7 +-
 2 files changed, 72 insertions(+), 5 deletions(-)

diff --git a/OSBindings/Mac/Clock SignalTests/65816AddressingTests.swift b/OSBindings/Mac/Clock SignalTests/65816AddressingTests.swift
index eaa0c4118..829d56527 100644
--- a/OSBindings/Mac/Clock SignalTests/65816AddressingTests.swift	
+++ b/OSBindings/Mac/Clock SignalTests/65816AddressingTests.swift	
@@ -180,14 +180,26 @@ class WDC65816AddressingTests: XCTestCase {
 		XCTAssertEqual(machine.value(for: .A), 0xcdab)
 	}
 
-
-	// TODO: all tests from this point downward.
-
 	func testDirextX8() {
 		// "If the D register is $FF00, the X register is $000A, and
 		// the e flag is 1 (note that this means the m flag must be 1),
 		// then LDA $FE,X loads the low byte of the data from
 		// address $00FF08"
+
+		let machine = machine8()
+
+		machine.setValue(0xff00, for: .direct)
+		machine.setValue(0x000a, for: .X)
+
+		machine.setValue(0xab, forAddress: 0xff08)
+
+		// LDA $fe, X; NOP
+		machine.setData(Data([0xb5, 0xfe, 0xea]), atAddress: 0x0200)
+
+		machine.setValue(0x200, for: .programCounter)
+		machine.runForNumber(ofCycles: 5)
+
+		XCTAssertEqual(machine.value(for: .A), 0xab)
 	}
 
 	func testDirectX16() {
@@ -195,6 +207,21 @@ class WDC65816AddressingTests: XCTestCase {
 		// m flag is 0 (note that this means the e flag must be 0), then
 		// LDA $FE,X loads the low byte of the data from address $000008,
 		// and the high byte from address $000009"
+		let machine = machine16()
+
+		machine.setValue(0xff00, for: .direct)
+		machine.setValue(0x000a, for: .X)
+
+		machine.setValue(0xab, forAddress: 0x0008)
+		machine.setValue(0xcd, forAddress: 0x0009)
+
+		// LDA $fe, X; NOP
+		machine.setData(Data([0xb5, 0xfe, 0xea]), atAddress: 0x0200)
+
+		machine.setValue(0x200, for: .programCounter)
+		machine.runForNumber(ofCycles: 6)
+
+		XCTAssertEqual(machine.value(for: .A), 0xcdab)
 	}
 
 	func testDirectIndirect8() {
@@ -205,6 +232,23 @@ class WDC65816AddressingTests: XCTestCase {
 		//	* $00FF00 contains $FF
 		//	* $00FFFF contains $FF
 		// then LDA ($FF) loads the low byte of the data from address $12FFFF."
+		let machine = machine8()
+
+		machine.setValue(0xff00, for: .direct)
+		machine.setValue(0x12, for: .dataBank)
+
+		machine.setValue(0xff, forAddress: 0xff00)
+		machine.setValue(0xff, forAddress: 0xffff)
+
+		machine.setValue(0xab, forAddress: 0x12ffff)
+
+		// LDA ($ff); NOP
+		machine.setData(Data([0xb2, 0xff, 0xea]), atAddress: 0x0200)
+
+		machine.setValue(0x200, for: .programCounter)
+		machine.runForNumber(ofCycles: 6)
+
+		XCTAssertEqual(machine.value(for: .A), 0xab)
 	}
 
 	func testDirectIndirect16() {
@@ -216,8 +260,28 @@ class WDC65816AddressingTests: XCTestCase {
 		//	* $00FFFF contains $FF
 		// then LDA ($FF) loads the low byte of the data from address $12FFFF, and
 		// the high byte from $130000."
+		let machine = machine16()
+
+		machine.setValue(0xff00, for: .direct)
+		machine.setValue(0x12, for: .dataBank)
+
+		machine.setValue(0xff, forAddress: 0x0000)
+		machine.setValue(0xff, forAddress: 0xffff)
+
+		machine.setValue(0xab, forAddress: 0x12ffff)
+		machine.setValue(0xcd, forAddress: 0x130000)
+
+		// LDA ($ff); NOP
+		machine.setData(Data([0xb2, 0xff, 0xea]), atAddress: 0x0200)
+
+		machine.setValue(0x200, for: .programCounter)
+		machine.runForNumber(ofCycles: 7)
+
+		XCTAssertEqual(machine.value(for: .A), 0xcdab)
 	}
 
+	// TODO: all tests from this point downward.
+
 	func testDirectIndirectLong() {
 		// "If the D register is $FF00 and the m flag is 0, then for LDA [$FE], the
 		// address of the low byte of the pointer is $00FFFE, the address of the middle
diff --git a/Processors/65816/Implementation/65816Implementation.hpp b/Processors/65816/Implementation/65816Implementation.hpp
index eca58721a..35d5addf9 100644
--- a/Processors/65816/Implementation/65816Implementation.hpp
+++ b/Processors/65816/Implementation/65816Implementation.hpp
@@ -278,17 +278,20 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
 			continue;
 
 			case OperationConstructDirect:
-				// TODO: is this address correct in emulation mode when the low byte is zero?
 				data_address_ = (direct_ + instruction_buffer_.value) & 0xffff;
 				data_address_increment_mask_ = 0x00'ff'ff;
 				if(!(direct_&0xff)) {
+					// If the low byte is 0 and this is emulation mode, incrementing
+					// is restricted to the low byte.
+					data_address_increment_mask_ = e_masks_[1];
 					++next_op_;
 				}
 			continue;
 
 			case OperationConstructDirectIndirect:
-				data_address_ = data_bank_ + direct_ + data_buffer_.value;
+				data_address_ = data_bank_ + data_buffer_.value;
 				data_address_increment_mask_ = 0xff'ff'ff;
+				data_buffer_.clear();
 			continue;
 
 			case OperationConstructDirectIndexedIndirect: