From e1aded0d9577c9d9751c2b5c4a93580a8806905c Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 21 Aug 2017 20:43:12 -0400
Subject: [PATCH] Allows Z80 users to opt out of support for the bus request
 line. Which both now do.

---
 Machines/AmstradCPC/AmstradCPC.cpp | 2 +-
 Machines/ZX8081/ZX8081.cpp         | 2 +-
 Processors/Z80/Z80.hpp             | 8 +++++---
 3 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/Machines/AmstradCPC/AmstradCPC.cpp b/Machines/AmstradCPC/AmstradCPC.cpp
index a704ee549..3d82513e4 100644
--- a/Machines/AmstradCPC/AmstradCPC.cpp
+++ b/Machines/AmstradCPC/AmstradCPC.cpp
@@ -992,7 +992,7 @@ class ConcreteMachine:
 			}
 		}
 
-		CPU::Z80::Processor<ConcreteMachine> z80_;
+		CPU::Z80::Processor<ConcreteMachine, false> z80_;
 
 		CRTCBusHandler crtc_bus_handler_;
 		Motorola::CRTC::CRTC6845<CRTCBusHandler> crtc_;
diff --git a/Machines/ZX8081/ZX8081.cpp b/Machines/ZX8081/ZX8081.cpp
index c79b9e58a..6758c6853 100644
--- a/Machines/ZX8081/ZX8081.cpp
+++ b/Machines/ZX8081/ZX8081.cpp
@@ -330,7 +330,7 @@ class ConcreteMachine:
 		HalfCycles get_typer_frequency() { return Cycles(390000); }
 
 	private:
-		CPU::Z80::Processor<ConcreteMachine> z80_;
+		CPU::Z80::Processor<ConcreteMachine, false> z80_;
 
 		std::shared_ptr<Video> video_;
 		std::vector<uint8_t> zx81_rom_, zx80_rom_;
diff --git a/Processors/Z80/Z80.hpp b/Processors/Z80/Z80.hpp
index 8dde6906a..a6db04055 100644
--- a/Processors/Z80/Z80.hpp
+++ b/Processors/Z80/Z80.hpp
@@ -9,6 +9,7 @@
 #ifndef Z80_hpp
 #define Z80_hpp
 
+#include <cassert>
 #include <cstdint>
 #include <cstring>
 #include <cstdio>
@@ -180,7 +181,7 @@ class BusHandler {
 	order to provide the bus on which the Z80 operates and @c flush(), which is called upon completion of a continuous run
 	of cycles to allow a subclass to bring any on-demand activities up to date.
 */
-template <class T> class Processor {
+template <class T, bool uses_bus_request> class Processor {
 	private:
 		T &bus_handler_;
 
@@ -910,7 +911,7 @@ template <class T> class Processor {
 			while(1) {
 
 				do_bus_acknowledge:
-				while(bus_request_line_) {
+				while(uses_bus_request && bus_request_line_) {
 					static PartialMachineCycle bus_acknowledge_cycle = {PartialMachineCycle::BusAcknowledge, HalfCycles(2), nullptr, nullptr, false};
 					number_of_cycles_ -= bus_handler_.perform_machine_cycle(bus_acknowledge_cycle) + HalfCycles(1);
 					if(!number_of_cycles_) {
@@ -946,7 +947,7 @@ template <class T> class Processor {
 							number_of_cycles_ -= operation->machine_cycle.length;
 							last_request_status_ = request_status_;
 							number_of_cycles_ -= bus_handler_.perform_machine_cycle(operation->machine_cycle);
-							if(bus_request_line_) goto do_bus_acknowledge;
+							if(uses_bus_request && bus_request_line_) goto do_bus_acknowledge;
 						break;
 						case MicroOp::MoveToNextProgram:
 							advance_operation();
@@ -1953,6 +1954,7 @@ template <class T> class Processor {
 			Sets the logical value of the bus request line.
 		*/
 		void set_bus_request_line(bool value) {
+			assert(uses_bus_request);
 			bus_request_line_ = value;
 		}