From bd69948d373eadc9575d1ae18ffe499b17327d32 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 18 Dec 2021 17:53:11 -0500
Subject: [PATCH] The Copper can now skip `Chipset::perform`.

---
 Machines/Amiga/Chipset.cpp | 2 +-
 Machines/Amiga/Chipset.hpp | 2 ++
 Machines/Amiga/Copper.cpp  | 9 +--------
 3 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/Machines/Amiga/Chipset.cpp b/Machines/Amiga/Chipset.cpp
index 89c8eb943..53c26dc17 100644
--- a/Machines/Amiga/Chipset.cpp
+++ b/Machines/Amiga/Chipset.cpp
@@ -808,7 +808,7 @@ void Chipset::update_interrupts() {
 void Chipset::perform(const CPU::MC68000::Microcycle &cycle) {
 	using Microcycle = CPU::MC68000::Microcycle;
 
-	const uint32_t register_address = *cycle.address & 0x1fe;
+	const uint32_t register_address = *cycle.address & ChipsetAddressMask;
 	if(cycle.operation & Microcycle::Read) {
 		cycle.set_value16(read<true>(register_address));
 	} else {
diff --git a/Machines/Amiga/Chipset.hpp b/Machines/Amiga/Chipset.hpp
index 104b74d53..a822624c3 100644
--- a/Machines/Amiga/Chipset.hpp
+++ b/Machines/Amiga/Chipset.hpp
@@ -110,6 +110,8 @@ class Chipset: private ClockingHint::Observer {
 		// MARK: - Register read/write functions.
 		template <bool allow_conversion> uint16_t read(uint32_t address);
 		template <bool allow_conversion> void write(uint32_t address, uint16_t value);
+		static constexpr uint32_t ChipsetAddressMask = 0x1fe;
+		friend class Copper;
 
 		// MARK: - E Clock and keyboard dividers.
 
diff --git a/Machines/Amiga/Copper.cpp b/Machines/Amiga/Copper.cpp
index a668953eb..959eb0a13 100644
--- a/Machines/Amiga/Copper.cpp
+++ b/Machines/Amiga/Copper.cpp
@@ -114,14 +114,7 @@ bool Copper::advance_dma(uint16_t position, uint16_t blitter_status) {
 						break;
 					}
 
-					// Construct a 68000-esque Microcycle in order to be able to perform the access.
-					CPU::MC68000::Microcycle cycle;
-					cycle.operation = CPU::MC68000::Microcycle::SelectWord;
-					uint32_t full_address = instruction_[0];
-					CPU::RegisterPair16 data = instruction_[1];
-					cycle.address = &full_address;
-					cycle.value = &data;
-					chipset_.perform(cycle);
+					chipset_.write<true>(instruction_[0] & Chipset::ChipsetAddressMask, instruction_[1]);
 				}
 
 				// Roll onto the next command.