From fa066cbd0430e9117384ebc21e54e2e0466d52f4 Mon Sep 17 00:00:00 2001
From: Frank <fdeweers@gmail.com>
Date: Fri, 19 Aug 2022 00:22:39 +0200
Subject: [PATCH] Emu: Add cycle accurate timing

---
 src/cpu.cpp  |  3 ---
 src/emu.cpp  | 24 +++++++++++++++---------
 src/emu.h    | 16 +++++++++++-----
 src/main.cpp | 15 +++++++++------
 src/ppu.cpp  |  3 ++-
 5 files changed, 37 insertions(+), 24 deletions(-)

diff --git a/src/cpu.cpp b/src/cpu.cpp
index 9277c05..ca7547e 100644
--- a/src/cpu.cpp
+++ b/src/cpu.cpp
@@ -8,7 +8,6 @@
 #include <cstdint> // uint8_t, uint32_t
 
 #include "cpu.h"
-#include "emu.h"
 #include "ruc/format/print.h"
 
 CPU::CPU(uint32_t frequency)
@@ -28,8 +27,6 @@ void CPU::update()
 	}
 
 	print("This is an update from the CPU\n");
-	Emu::the().writeMemory("RAM", 123, 42);
-	print("fff");
 }
 
 void CPU::add(uint8_t opcode, uint8_t immediate)
diff --git a/src/emu.cpp b/src/emu.cpp
index 549a1c4..fb92574 100644
--- a/src/emu.cpp
+++ b/src/emu.cpp
@@ -7,32 +7,38 @@
 void Emu::init(uint32_t frequency)
 {
 	m_frequency = frequency;
+	m_timestep = 1.0 / m_frequency * 1000000;
 }
 
 void Emu::update()
 {
-	for (auto unit : m_processing_units) {
-		if (m_cycle % (m_frequency / unit->frequency()) == 0) {
-			unit->update();
+	double time = m_timer.elapsedNanoseconds() / 1000.0;
+	m_cycle_time += (time - m_previous_time);
+	m_previous_time = time;
+	if (m_cycle_time > m_timestep) {
+		for (auto unit : m_processing_units) {
+			if (m_cycle % (m_frequency / unit.second->frequency()) == 0) {
+				unit.second->update();
+			}
 		}
+		m_cycle_time -= m_timestep;
+		m_cycle++;
 	}
-	m_cycle++;
 }
 
-void Emu::addProcessingUnit(ProcessingUnit* processing_unit)
+void Emu::addProcessingUnit(const char* name, ProcessingUnit* processing_unit)
 {
-	m_processing_units.push_back(processing_unit);
+	m_processing_units.emplace(name, processing_unit);
 }
 
 void Emu::addMemorySpace(const char* name, uint32_t size)
 {
-	std::vector<uint8_t> memory(size);
+	std::vector<uint32_t> memory(size);
 	m_memory_spaces.emplace(name, memory);
 }
 
-void Emu::writeMemory(const char* memory_space, uint32_t location, uint8_t value)
+void Emu::writeMemory(const char* memory_space, uint32_t location, uint32_t value)
 {
-	print("{} {} {}\n", memory_space, location, value);
 	m_memory_spaces[memory_space][location] = value;
 }
 
diff --git a/src/emu.h b/src/emu.h
index a6d6076..52edb84 100644
--- a/src/emu.h
+++ b/src/emu.h
@@ -6,6 +6,7 @@
 
 #include "processing-unit.h"
 #include "ruc/singleton.h"
+#include "ruc/timer.h"
 
 class Emu final : public ruc::Singleton<Emu> {
 public:
@@ -15,17 +16,22 @@ public:
 
 	void update();
 
-	void addProcessingUnit(ProcessingUnit* processing_unit);
+	void addProcessingUnit(const char* name, ProcessingUnit* processing_unit);
 	void addMemorySpace(const char* name, uint32_t size);
 
-	void writeMemory(const char* memory_space, uint32_t location, uint8_t value);
+	void writeMemory(const char* memory_space, uint32_t location, uint32_t value);
 
 	uint8_t readMemory(const char* memory_space, uint32_t location);
 
 private:
-	uint32_t m_frequency;
+	uint32_t m_frequency = 0;
+	double m_timestep = 0;
 	uint32_t m_cycle = 0;
+	double m_cycle_time = 0;
+	double m_previous_time = 0;
 
-	std::vector<ProcessingUnit*> m_processing_units;
-	std::unordered_map<const char*, std::vector<uint8_t>> m_memory_spaces;
+	ruc::Timer m_timer;
+
+	std::unordered_map<const char*, ProcessingUnit*> m_processing_units;
+	std::unordered_map<const char*, std::vector<uint32_t>> m_memory_spaces;
 };
diff --git a/src/main.cpp b/src/main.cpp
index 3f48447..c6b342e 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -11,17 +11,20 @@ int main(int argc, char* argv[])
 
 	printf("%fms\n", t.elapsedNanoseconds() / 1000000.0);
 
-	Emu::the().init(4000000);
+	Emu::the().init(8000000);
 
-	CPU cpu(1000000);
-	PPU ppu(2000000);
+	CPU cpu(8000000);
+	PPU ppu(4000000);
 
-	Emu::the().addProcessingUnit(&cpu);
-	Emu::the().addProcessingUnit(&ppu);
+	Emu::the().addProcessingUnit("cpu", &cpu);
+	Emu::the().addProcessingUnit("ppu", &ppu);
 
 	Emu::the().addMemorySpace("RAM", 1024);
+	Emu::the().addMemorySpace("VRAM", 1024);
+	Emu::the().addMemorySpace("ROM", 1024);
+	Emu::the().addMemorySpace("CARDROM", 1024);
 
-	for (int i = 0; i < 1000; i++) {
+	while (true) {
 		Emu::the().update();
 	}
 
diff --git a/src/ppu.cpp b/src/ppu.cpp
index 2fe91c8..5ffe542 100644
--- a/src/ppu.cpp
+++ b/src/ppu.cpp
@@ -6,6 +6,7 @@
  */
 
 #include "ppu.h"
+#include "ruc/format/print.h"
 #include <iostream>
 
 PPU ::PPU(unsigned int frequency)
@@ -19,5 +20,5 @@ PPU ::~PPU()
 
 void PPU::update()
 {
-	printf("ppu update\n");
+	print("ppu update\n");
 }