From 4da023c236d89299bd400a67b7b23afa2923ce2c Mon Sep 17 00:00:00 2001
From: wheremyfoodat <gponiris2004@gmail.com>
Date: Sat, 24 Sep 2022 03:57:21 +0300
Subject: [PATCH] [Kernel/Memory] Implement DATETIME0

---
 include/kernel/config_mem.hpp |  3 ++-
 include/memory.hpp            |  1 +
 src/core/memory.cpp           | 16 ++++++++++++++++
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/include/kernel/config_mem.hpp b/include/kernel/config_mem.hpp
index 90588b77..f26e91c8 100644
--- a/include/kernel/config_mem.hpp
+++ b/include/kernel/config_mem.hpp
@@ -6,6 +6,7 @@ namespace ConfigMem {
 	enum : u32 {
 		KernelVersionMinor = 0x1FF80002,
 		KernelVersionMajor = 0x1FF80003,
-		AppMemAlloc = 0x1FF80040
+		AppMemAlloc = 0x1FF80040,
+		Datetime0 = 0x1FF81020
 	};
 }
\ No newline at end of file
diff --git a/include/memory.hpp b/include/memory.hpp
index 5cfe1c63..906255fb 100644
--- a/include/memory.hpp
+++ b/include/memory.hpp
@@ -118,6 +118,7 @@ public:
 
 	u32 getLinearHeapVaddr();
 	u8* getFCRAM() { return fcram; }
+	u64 timeSince3DSEpoch();
 
 	// Returns whether "addr" is aligned to a page (4096 byte) boundary
 	static constexpr bool isAligned(u32 addr) {
diff --git a/src/core/memory.cpp b/src/core/memory.cpp
index 1dc67938..be966c7e 100644
--- a/src/core/memory.cpp
+++ b/src/core/memory.cpp
@@ -2,6 +2,7 @@
 #include "config_mem.hpp"
 #include "resource_limits.hpp"
 #include <cassert>
+#include <chrono> // For time since epoch
 
 using namespace KernelMemoryTypes;
 
@@ -85,7 +86,11 @@ u32 Memory::read32(u32 vaddr) {
 		return *(u32*)(pointer + offset);
 	} else {
 		switch (vaddr) {
+			case ConfigMem::Datetime0: return u32(timeSince3DSEpoch()); // ms elapsed since Jan 1 1900, bottom 32 bits
+			case ConfigMem::Datetime0 + 4: return u32(timeSince3DSEpoch() >> 32); // top 32 bits
+
 			case ConfigMem::AppMemAlloc: return appResourceLimits.maxCommit;
+			case 0x1FF81000: return 0; // TODO: Figure out what this config mem address does
 			default:
 				Helpers::panic("Unimplemented 32-bit read, addr: %08X", vaddr);
 				break;
@@ -350,4 +355,15 @@ void Memory::mapGSPSharedMemory(u32 vaddr, u32 myPerms, u32 otherPerms) {
 	const auto result = allocateMemory(vaddr, paddr, size, true, r, w, x);
 	if (!result.has_value())
 		Helpers::panic("Failed to allocated GSP shared memory");
+}
+
+// Get the number of ms since Jan 1 1900
+u64 Memory::timeSince3DSEpoch() {
+	using namespace std::chrono;
+	
+	// ms since Jan 1 1970
+	milliseconds ms = duration_cast<milliseconds>(system_clock::now().time_since_epoch());
+	// ms between Jan 1 1900 and Jan 1 1970 (2208988800 seconds elapsed between the two)
+	const u64 offset = 2208988800ull * 1000;
+	return ms.count() + offset;
 }
\ No newline at end of file