From e3f6da6994af9f6ed82c9eff97d83ee964cf99ae Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 8 Aug 2018 20:00:14 -0400
Subject: [PATCH] Implements the 65C02 NOPs.

---
 .../Clock SignalTests/KlausDormannTests.swift  |  2 ++
 Processors/6502/6502.hpp                       |  3 ++-
 .../6502/Implementation/6502Implementation.hpp | 11 ++++++++++-
 Processors/6502/Implementation/6502Storage.cpp | 18 ++++++++++++++++++
 4 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/OSBindings/Mac/Clock SignalTests/KlausDormannTests.swift b/OSBindings/Mac/Clock SignalTests/KlausDormannTests.swift
index 71a82f171..7da2aa683 100644
--- a/OSBindings/Mac/Clock SignalTests/KlausDormannTests.swift	
+++ b/OSBindings/Mac/Clock SignalTests/KlausDormannTests.swift	
@@ -76,6 +76,8 @@ class KlausDormannTests: XCTestCase {
 				case 0x0730: return "BBS: branch not taken"
 				case 0x0733: return "BBR: branch taken"
 
+				case 0x2884: return "JMP (abs) exhibited 6502 page-crossing bug"
+
 				case 0: return "Didn't find tests"
 				default: return "Unknown error at \(String(format:"%04x", address))"
 			}
diff --git a/Processors/6502/6502.hpp b/Processors/6502/6502.hpp
index 37a2e6eca..00fb75429 100644
--- a/Processors/6502/6502.hpp
+++ b/Processors/6502/6502.hpp
@@ -204,7 +204,7 @@ template <typename T, bool uses_ready_line> class Processor: public ProcessorBas
 		/*!
 			Constructs an instance of the 6502 that will use @c bus_handler for all bus communications.
 		*/
-		Processor(Personality personality, T &bus_handler) : ProcessorBase(personality), bus_handler_(bus_handler) {}
+		Processor(Personality personality, T &bus_handler) : ProcessorBase(personality), personality_(personality), bus_handler_(bus_handler) {}
 
 		/*!
 			Runs the 6502 for a supplied number of cycles.
@@ -221,6 +221,7 @@ template <typename T, bool uses_ready_line> class Processor: public ProcessorBas
 		void set_ready_line(bool active);
 
 	private:
+		Personality personality_;
 		T &bus_handler_;
 };
 
diff --git a/Processors/6502/Implementation/6502Implementation.hpp b/Processors/6502/Implementation/6502Implementation.hpp
index 4d3cca800..3a3ef35a5 100644
--- a/Processors/6502/Implementation/6502Implementation.hpp
+++ b/Processors/6502/Implementation/6502Implementation.hpp
@@ -93,7 +93,16 @@ if(number_of_cycles <= Cycles(0)) break;
 					} break;
 
 					case CycleFetchOperand:
-						read_mem(operand_, pc_.full);
+						if(
+							personality_ == P6502 ||
+							(operation_&7) != 3 ||
+							operation_ == 0xcb ||
+							operation_ == 0xdb
+						) {
+							read_mem(operand_, pc_.full);
+						} else {
+							printf("Skipping %02x\n", operation_);
+						}
 					break;
 
 					case OperationDecodeOperation:
diff --git a/Processors/6502/Implementation/6502Storage.cpp b/Processors/6502/Implementation/6502Storage.cpp
index 264287f4e..517a09420 100644
--- a/Processors/6502/Implementation/6502Storage.cpp
+++ b/Processors/6502/Implementation/6502Storage.cpp
@@ -242,6 +242,24 @@ ProcessorStorage::ProcessorStorage(Personality personality) {
 		for(int location = 0x0f; location <= 0xff; location += 0x10) {
 			Install(location, Program(OperationLoadAddressZeroPage, CycleFetchOperandFromAddress, OperationBBRBBS));
 		}
+
+		// Add NOPs.
+
+		// The 1-byte, 1-cycle (!) NOPs.
+		for(int c = 0x03; c <= 0xf3; c += 0x10) {
+			Install(c, ImpliedNop());
+		}
+		for(int c = 0x0b; c <= 0xbb; c += 0x10) {
+			Install(c, ImpliedNop());
+		}
+		for(int c = 0xeb; c <= 0xfb; c += 0x10) {
+			Install(c, ImpliedNop());
+		}
+
+		// The 2-byte, 2-cycle NOPs that the 6502 doesn't have.
+		for(int c = 0x02; c <= 0x62; c += 0x10) {
+			Install(c, ImmediateNop());
+		}
 	}
 #undef Install
 }