From c33d7e5dfbbc0cf924870ea315c7e7a6513d765f Mon Sep 17 00:00:00 2001
From: wheremyfoodat <gponiris2004@gmail.com>
Date: Thu, 15 Sep 2022 17:50:14 +0300
Subject: [PATCH] Implement main thread stack

---
 include/memory.hpp  |  6 ++++--
 src/core/memory.cpp | 15 +++++++++++++++
 src/emulator.cpp    |  1 +
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/include/memory.hpp b/include/memory.hpp
index 8c11e2e8..04be0286 100644
--- a/include/memory.hpp
+++ b/include/memory.hpp
@@ -11,8 +11,10 @@ namespace VirtualAddrs {
 		ExecutableEnd = 0x00100000 + 0x03F00000,
 
 		// Stack for main ARM11 thread.
-		// Typically 0x4000 bytes
-		StackTop = 0x10000000
+		// Typically 0x4000 bytes, determined by exheader
+		StackTop = 0x10000000,
+		StackBottom = 0x0FFFC000,
+		StackSize = 0x4000
 	};
 }
 
diff --git a/src/core/memory.cpp b/src/core/memory.cpp
index b7ab4793..2d4a1055 100644
--- a/src/core/memory.cpp
+++ b/src/core/memory.cpp
@@ -5,6 +5,8 @@ Memory::Memory() {
 	readTable.resize(totalPageCount, 0);
 	writeTable.resize(totalPageCount, 0);
 
+	constexpr u32 fcramPageCount = 128_MB / pageSize;
+
 	// Map 63MB of FCRAM in the executable section as read/write
 	// TODO: This should probably be read-only, but making it r/w shouldn't hurt?
 	// Because if that were the case then writes would cause data aborts, so games wouldn't write to read-only memory
@@ -15,6 +17,19 @@ Memory::Memory() {
 		readTable[page] = pointer;
 		writeTable[page++] = pointer;
 	}
+
+	// Map stack pages as R/W
+	// We have 16KB for the stack, so we allocate the last 4 pages of FCRAM for the stack
+	u32 stackPageCount = VirtualAddrs::StackSize / pageSize;
+	u32 fcramStackPage = fcramPageCount - 4;
+	page = VirtualAddrs::StackBottom / pageSize;
+
+	for (u32 i = 0; i < 4; i++) {
+		auto pointer = (uintptr_t)&fcram[fcramStackPage * pageSize];
+		readTable[page] = pointer;
+		writeTable[page++] = pointer;
+		fcramStackPage++;
+	}
 }
 
 u8 Memory::read8(u32 vaddr) {
diff --git a/src/emulator.cpp b/src/emulator.cpp
index fcb0c841..445ccee1 100644
--- a/src/emulator.cpp
+++ b/src/emulator.cpp
@@ -38,6 +38,7 @@ bool Emulator::loadELF(std::filesystem::path& path) {
     if (!entrypoint.has_value())
         return false;
 
+    cpu.setReg(13, VirtualAddrs::StackTop); // Set initial SP
     cpu.setReg(15, entrypoint.value()); // Set initial PC
     return true;
 }
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