From 047c505b96287d82dff47c105c909a9965fde9ac Mon Sep 17 00:00:00 2001
From: Tharo <17233964+Thar0@users.noreply.github.com>
Date: Thu, 19 Dec 2024 05:38:44 +0000
Subject: [PATCH] Remove gSystemHeap and the system_heap spec segment, use
 _buffersSegmentEnd to represent the start of the system heap (#1767)

---
 include/buffers.h             | 1 -
 include/segment_symbols.h     | 2 +-
 linker_scripts/final/extra.ld | 2 +-
 spec                          | 7 -------
 src/buffers/system_heap.c     | 6 ------
 src/code/main.c               | 2 +-
 tools/disasm/variables.txt    | 2 +-
 7 files changed, 4 insertions(+), 18 deletions(-)
 delete mode 100644 src/buffers/system_heap.c

diff --git a/include/buffers.h b/include/buffers.h
index 4159173a9e..22cf065894 100644
--- a/include/buffers.h
+++ b/include/buffers.h
@@ -25,7 +25,6 @@ extern u8 gGfxSPTaskYieldBuffer[OS_YIELD_DATA_SIZE];
 extern STACK(gGfxSPTaskStack, 0x400);
 extern GfxPool gGfxPools[2];
 extern u8 gAudioHeap[0x138000];
-extern u8 gSystemHeap[];
 
 
 typedef union {
diff --git a/include/segment_symbols.h b/include/segment_symbols.h
index 922f818d7c..c29b228384 100644
--- a/include/segment_symbols.h
+++ b/include/segment_symbols.h
@@ -78,7 +78,7 @@ DECLARE_SEGMENT(code)
 DECLARE_ROM_SEGMENT(code)
 DECLARE_BSS_SEGMENT(code)
 
-DECLARE_SEGMENT(system_heap)
+DECLARE_SEGMENT(buffers)
 
 DECLARE_OVERLAY_SEGMENT(kaleido_scope)
 DECLARE_OVERLAY_SEGMENT(player_actor)
diff --git a/linker_scripts/final/extra.ld b/linker_scripts/final/extra.ld
index fddac01c98..74a533edd9 100644
--- a/linker_scripts/final/extra.ld
+++ b/linker_scripts/final/extra.ld
@@ -3,5 +3,5 @@ ENTRY(entrypoint);
 ASSERT ((_bootSegmentRomEnd <= 0x101000), "Error: _bootSegmentRomEnd is larger than 1 MB");
 
 // TODO: This should be checking for an address a lot earlier than this one.
-ASSERT ((_system_heapSegmentStart < 0x80780000), "Error: The game is overflowing the RAM limit for non-overlay segments.");
+ASSERT ((_buffersSegmentEnd < 0x80780000), "Error: The game is overflowing the RAM limit for non-overlay segments.");
 ASSERT ((_framebuffer_hiSegmentStart == 0x80780000), "Error: framebuffer_hi shifted?");
diff --git a/spec b/spec
index 3d0b8d3678..b0df5c0b68 100644
--- a/spec
+++ b/spec
@@ -794,13 +794,6 @@ beginseg
     include "$(BUILD_DIR)/src/buffers/audio_heap.o"
 endseg
 
-beginseg
-    name "system_heap"
-    flags NOLOAD
-    // This segment is just a dummy that is used to know where the other buffers (non framebuffers) end
-    include "$(BUILD_DIR)/src/buffers/system_heap.o"
-endseg
-
 beginseg
     name "framebuffer_hi"
     flags NOLOAD
diff --git a/src/buffers/system_heap.c b/src/buffers/system_heap.c
deleted file mode 100644
index df3d79003b..0000000000
--- a/src/buffers/system_heap.c
+++ /dev/null
@@ -1,6 +0,0 @@
-#include "buffers.h"
-
-// Don't add symbols here unless you know what you are doing.
-
-// Dummy, marks the start of system_heap space whose actual size depends on the spec
-u8 gSystemHeap[UNK_SIZE] ALIGNED(16);
diff --git a/src/code/main.c b/src/code/main.c
index 953cac7c03..13dd030c54 100644
--- a/src/code/main.c
+++ b/src/code/main.c
@@ -60,7 +60,7 @@ void Main(void* arg) {
     Check_RegionIsSupported();
     Check_ExpansionPak();
 
-    sysHeap = (uintptr_t)SEGMENT_START(system_heap);
+    sysHeap = (uintptr_t)SEGMENT_END(buffers);
     fb = FRAMEBUFFERS_START_ADDR;
     gSystemHeapSize = fb - sysHeap;
     SystemHeap_Init((void*)sysHeap, gSystemHeapSize);
diff --git a/tools/disasm/variables.txt b/tools/disasm/variables.txt
index 57aa4a263b..3d0ea3c5e5 100644
--- a/tools/disasm/variables.txt
+++ b/tools/disasm/variables.txt
@@ -4204,7 +4204,7 @@
     0x80209AA0:("gGfxSPTaskStack","u8","[0x400]",0x400),
     0x80209EA0:("gGfxPools","GfxPool","[2]",0x40620),
     0x8024A4C0:("gAudioHeap","u8","[0x138000]",0x138000),
-    0x803824C0:("gSystemHeap","u8","[UNK_SIZE]",0x3fdb40),
+    0x803824C0:("_buffersSegmentEnd","u8","[UNK_SIZE]",0x3fdb40),
     0x80780000:("gHiBuffer","BufferHigh","",0x80000),
     0x80800860:("titleRotation","s16","",0x2),
     0x80800868:("D_80800868","UNK_TYPE1","",0x1),