diff --git a/include/alignment.h b/include/alignment.h
index 7a3b94ea2c..e26a1d3f33 100644
--- a/include/alignment.h
+++ b/include/alignment.h
@@ -13,4 +13,16 @@
 #define ALIGNED8
 #endif
 
+#ifdef __sgi /* IDO compiler */
+#define ALIGNOF(x) __builtin_alignof(x)
+#elif (__STDC_VERSION__ >= 201112L) /* C11 */
+#define ALIGNOF(x) _Alignof(x)
+#else /* __GNUC__ */
+#define ALIGNOF(x) __alignof__(x)
+#endif
+
+#define ALIGN_MASK(n) (~((n) - 1))
+
+#define ALIGNOF_MASK(x) ALIGN_MASK(ALIGNOF(x))
+
 #endif
diff --git a/include/functions.h b/include/functions.h
index 9a42f50ff7..3502a6dc96 100644
--- a/include/functions.h
+++ b/include/functions.h
@@ -1460,35 +1460,6 @@ void func_800C213C(PreRender* this, Gfx** gfxp);
 void PreRender_RestoreFramebuffer(PreRender* this, Gfx** gfxp);
 void PreRender_CopyImageRegion(PreRender* this, Gfx** gfxp);
 void PreRender_ApplyFilters(PreRender* this);
-void THGA_Ct(TwoHeadGfxArena* thga, Gfx* start, u32 size);
-void THGA_Dt(TwoHeadGfxArena* thga);
-u32 THGA_IsCrash(TwoHeadGfxArena* thga);
-void THGA_Init(TwoHeadGfxArena* thga);
-s32 THGA_GetSize(TwoHeadGfxArena* thga);
-Gfx* THGA_GetHead(TwoHeadGfxArena* thga);
-void THGA_SetHead(TwoHeadGfxArena* thga, Gfx* start);
-Gfx* THGA_GetTail(TwoHeadGfxArena* thga);
-Gfx* THGA_AllocStartArray8(TwoHeadGfxArena* thga, u32 count);
-Gfx* THGA_AllocStart8(TwoHeadGfxArena* thga);
-Gfx* THGA_AllocStart8Wrapper(TwoHeadGfxArena* thga);
-Gfx* THGA_AllocEnd(TwoHeadGfxArena* thga, u32 size);
-Gfx* THGA_AllocEndArray64(TwoHeadGfxArena* thga, u32 count);
-Gfx* THGA_AllocEnd64(TwoHeadGfxArena* thga);
-Gfx* THGA_AllocEndArray16(TwoHeadGfxArena* thga, u32 count);
-Gfx* THGA_AllocEnd16(TwoHeadGfxArena* thga);
-void* THA_GetHead(TwoHeadArena* tha);
-void THA_SetHead(TwoHeadArena* tha, void* start);
-void* THA_GetTail(TwoHeadArena* tha);
-void* THA_AllocStart(TwoHeadArena* tha, u32 size);
-void* THA_AllocStart1(TwoHeadArena* tha);
-void* THA_AllocEnd(TwoHeadArena* tha, u32 size);
-void* THA_AllocEndAlign16(TwoHeadArena* tha, u32 size);
-void* THA_AllocEndAlign(TwoHeadArena* tha, u32 size, u32 mask);
-s32 THA_GetSize(TwoHeadArena* tha);
-u32 THA_IsCrash(TwoHeadArena* tha);
-void THA_Init(TwoHeadArena* tha);
-void THA_Ct(TwoHeadArena* tha, void* ptr, u32 size);
-void THA_Dt(TwoHeadArena* tha);
 void AudioMgr_StopAllSfx(void);
 void func_800C3C80(AudioMgr* audioMgr);
 void AudioMgr_HandleRetrace(AudioMgr* audioMgr);
diff --git a/include/tha.h b/include/tha.h
new file mode 100644
index 0000000000..1f086b0016
--- /dev/null
+++ b/include/tha.h
@@ -0,0 +1,28 @@
+#ifndef THA_H
+#define THA_H
+
+#include "ultra64.h"
+#include "alignment.h"
+
+typedef struct {
+    /* 0x00 */ size_t size;
+    /* 0x04 */ void* start;
+    /* 0x08 */ void* head;
+    /* 0x0C */ void* tail;
+} TwoHeadArena; // size = 0x10
+
+void* THA_GetHead(TwoHeadArena* tha);
+void THA_SetHead(TwoHeadArena* tha, void* newHead);
+void* THA_GetTail(TwoHeadArena* tha);
+void* THA_AllocHead(TwoHeadArena* tha, size_t size);
+void* THA_AllocHeadByte(TwoHeadArena* tha);
+void* THA_AllocTail(TwoHeadArena* tha, size_t size);
+void* THA_AllocTailAlign16(TwoHeadArena* tha, size_t size);
+void* THA_AllocTailAlign(TwoHeadArena* tha, size_t size, uintptr_t mask);
+s32 THA_GetRemaining(TwoHeadArena* tha);
+u32 THA_IsCrash(TwoHeadArena* tha);
+void THA_Reset(TwoHeadArena* tha);
+void THA_Init(TwoHeadArena* tha, void* start, size_t size);
+void THA_Destroy(TwoHeadArena* tha);
+
+#endif
diff --git a/include/thga.h b/include/thga.h
new file mode 100644
index 0000000000..9d9e96950a
--- /dev/null
+++ b/include/thga.h
@@ -0,0 +1,33 @@
+#ifndef THGA_H
+#define THGA_H
+
+#include "tha.h"
+
+typedef union {
+    /* 0x00 */ TwoHeadArena tha;
+    struct {       // Same as TwoHeadArena, with different types and field names for the head and tail pointers
+        /* 0x00 */ size_t size;
+        /* 0x04 */ void* start;
+        /* 0x08 */ Gfx* p;
+        /* 0x0C */ void* d;
+    };
+} TwoHeadGfxArena; // size = 0x10
+
+void THGA_Init(TwoHeadGfxArena* thga, void* start, size_t size);
+void THGA_Destroy(TwoHeadGfxArena* thga);
+u32 THGA_IsCrash(TwoHeadGfxArena* thga);
+void THGA_Reset(TwoHeadGfxArena* thga);
+s32 THGA_GetRemaining(TwoHeadGfxArena* thga);
+Gfx* THGA_GetHead(TwoHeadGfxArena* thga);
+void THGA_SetHead(TwoHeadGfxArena* thga, Gfx* newHead);
+void* THGA_GetTail(TwoHeadGfxArena* thga);
+Gfx* THGA_AllocDisplayList(TwoHeadGfxArena* thga, size_t num);
+Gfx* THGA_AllocGfx(TwoHeadGfxArena* thga);
+Gfx* THGA_AllocGfx2(TwoHeadGfxArena* thga);
+void* THGA_AllocTail(TwoHeadGfxArena* thga, size_t size);
+Mtx* THGA_AllocMtxArray(TwoHeadGfxArena* thga, size_t num);
+Mtx* THGA_AllocMtx(TwoHeadGfxArena* thga);
+Vtx* THGA_AllocVtxArray(TwoHeadGfxArena* thga, size_t num);
+Vtx* THGA_AllocVtx(TwoHeadGfxArena* thga);
+
+#endif
diff --git a/include/z64.h b/include/z64.h
index 526921d074..8cfcfd160b 100644
--- a/include/z64.h
+++ b/include/z64.h
@@ -38,6 +38,8 @@
 #include "fault.h"
 #include "sched.h"
 #include "rumble.h"
+#include "tha.h"
+#include "thga.h"
 
 #define SCREEN_WIDTH  320
 #define SCREEN_HEIGHT 240
@@ -106,20 +108,6 @@ typedef struct {
     /* 0x12408 */ u16 tailMagic; // GFXPOOL_TAIL_MAGIC
 } GfxPool; // size = 0x12410
 
-typedef struct {
-    /* 0x0000 */ u32    size;
-    /* 0x0004 */ void*    bufp;
-    /* 0x0008 */ void*    head;
-    /* 0x000C */ void*    tail;
-} TwoHeadArena; // size = 0x10
-
-typedef struct {
-    /* 0x0000 */ u32    size;
-    /* 0x0004 */ Gfx*   bufp;
-    /* 0x0008 */ Gfx*   p;
-    /* 0x000C */ Gfx*   d;
-} TwoHeadGfxArena; // size = 0x10
-
 typedef struct GraphicsContext {
     /* 0x0000 */ Gfx* polyOpaBuffer; // Pointer to "Zelda 0"
     /* 0x0004 */ Gfx* polyXluBuffer; // Pointer to "Zelda 1"
diff --git a/spec b/spec
index dd2dc1036b..a8a6dbb534 100644
--- a/spec
+++ b/spec
@@ -385,6 +385,7 @@ beginseg
     include "build/src/code/z_kaleido_scope_call.o"
     include "build/src/code/z_play.o"
     include "build/src/code/PreRender.o"
+    include "build/src/code/TwoHeadGfxArena.o"
     include "build/src/code/TwoHeadArena.o"
     include "build/src/code/code_800C3C20.o"
     include "build/src/code/audioMgr.o"
diff --git a/src/code/TwoHeadArena.c b/src/code/TwoHeadArena.c
index 3340604607..271c2ae7ff 100644
--- a/src/code/TwoHeadArena.c
+++ b/src/code/TwoHeadArena.c
@@ -1,140 +1,135 @@
+/**
+ * @file TwoHeadArena.c
+ *
+ * This file implements a simple general purpose double-ended stack allocator.
+ *
+ * A double-ended stack allocator accepts allocations at either the "head" or "tail" of its allotted memory region.
+ * While in general this type of allocator could accept deallocations on the most recently allocated block at either
+ * end, this implementation does not support any individual deallocations; the only provided way to deallocate anything
+ * is to reset the entire arena, deallocating everything. This scheme is most applicable to allocating similar data
+ * with identical lifetime.
+ */
 #include "global.h"
 
-void THGA_Ct(TwoHeadGfxArena* thga, Gfx* start, u32 size) {
-    THA_Ct((TwoHeadArena*)thga, start, size);
-}
-
-void THGA_Dt(TwoHeadGfxArena* thga) {
-    THA_Dt((TwoHeadArena*)thga);
-}
-
-u32 THGA_IsCrash(TwoHeadGfxArena* thga) {
-    return THA_IsCrash((TwoHeadArena*)thga);
-}
-
-void THGA_Init(TwoHeadGfxArena* thga) {
-    THA_Init((TwoHeadArena*)thga);
-}
-
-s32 THGA_GetSize(TwoHeadGfxArena* thga) {
-    return THA_GetSize((TwoHeadArena*)thga);
-}
-
-Gfx* THGA_GetHead(TwoHeadGfxArena* thga) {
-    return THA_GetHead((TwoHeadArena*)thga);
-}
-
-void THGA_SetHead(TwoHeadGfxArena* thga, Gfx* start) {
-    THA_SetHead((TwoHeadArena*)thga, start);
-}
-
-Gfx* THGA_GetTail(TwoHeadGfxArena* thga) {
-    return THA_GetTail((TwoHeadArena*)thga);
-}
-
-Gfx* THGA_AllocStartArray8(TwoHeadGfxArena* thga, u32 count) {
-    return THA_AllocStart((TwoHeadArena*)thga, count * 8);
-}
-
-Gfx* THGA_AllocStart8(TwoHeadGfxArena* thga) {
-    return THGA_AllocStartArray8(thga, 1);
-}
-
-Gfx* THGA_AllocStart8Wrapper(TwoHeadGfxArena* thga) {
-    return THGA_AllocStart8(thga);
-}
-
-Gfx* THGA_AllocEnd(TwoHeadGfxArena* thga, u32 size) {
-    return THA_AllocEnd((TwoHeadArena*)thga, size);
-}
-
-Gfx* THGA_AllocEndArray64(TwoHeadGfxArena* thga, u32 count) {
-    return THGA_AllocEnd(thga, count * 0x40);
-}
-
-Gfx* THGA_AllocEnd64(TwoHeadGfxArena* thga) {
-    return THGA_AllocEnd(thga, 0x40);
-}
-
-Gfx* THGA_AllocEndArray16(TwoHeadGfxArena* thga, u32 count) {
-    return THGA_AllocEnd(thga, count * 0x10);
-}
-
-Gfx* THGA_AllocEnd16(TwoHeadGfxArena* thga) {
-    return THGA_AllocEnd(thga, 0x10);
-}
-
 void* THA_GetHead(TwoHeadArena* tha) {
     return tha->head;
 }
 
-void THA_SetHead(TwoHeadArena* tha, void* start) {
-    tha->head = start;
+void THA_SetHead(TwoHeadArena* tha, void* newHead) {
+    tha->head = newHead;
 }
 
 void* THA_GetTail(TwoHeadArena* tha) {
     return tha->tail;
 }
 
-void* THA_AllocStart(TwoHeadArena* tha, u32 size) {
+/**
+ * Allocates to the head of the Two Head Arena. The allocation will not have any alignment guarantees.
+ */
+void* THA_AllocHead(TwoHeadArena* tha, size_t size) {
     void* start = tha->head;
 
-    tha->head = (void*)((u32)tha->head + size);
+    tha->head = (u8*)tha->head + size;
     return start;
 }
 
-void* THA_AllocStart1(TwoHeadArena* tha) {
-    return THA_AllocStart(tha, 1);
+void* THA_AllocHeadByte(TwoHeadArena* tha) {
+    return THA_AllocHead(tha, 1);
 }
 
-void* THA_AllocEnd(TwoHeadArena* tha, u32 size) {
-    u32 mask;
+/**
+ * Allocates to the tail end of the Two Head Arena. The allocation will be aligned based on the size of the allocation.
+ * All allocations of 16 bytes or more will be aligned to 16-bytes. Otherwise, the alignment will be the largest power
+ * of 2 for which the size is a multiple, in order to accommodate the alignment requirements of any data types that can
+ * fit within the allocation.
+ */
+void* THA_AllocTail(TwoHeadArena* tha, size_t size) {
+    uintptr_t mask;
 
     if (size == 8) {
-        mask = ~7;
+        // Align 8 for multiples of 8
+        mask = ALIGN_MASK(8);
     } else if (size == 4 || size == 12) {
-        mask = ~3;
+        // Align 4 for multiples of 4
+        mask = ALIGN_MASK(4);
     } else if (size == 2 || size == 6 || size == 10 || size == 12 || size == 14) {
-        mask = ~1;
+        // Align 2 for multiples of 2
+        mask = ALIGN_MASK(2);
+    } else if (size >= 0x10) {
+        // Align 0x10 for allocations greater than 0x10
+        mask = ALIGN_MASK(0x10);
     } else {
-        mask = (size >= 0x10) ? ~0xF : 0;
+        //! @bug if size is less than 16 and odd the computation below will give NULL. The mask for this case would be
+        //! more sensible as ~0, for no extra alignment
+        mask = 0;
     }
 
-    tha->tail = (void*)((((u32)tha->tail & mask) - size) & mask);
+    tha->tail = (void*)((((uintptr_t)tha->tail & mask) - size) & mask);
     return tha->tail;
 }
 
-void* THA_AllocEndAlign16(TwoHeadArena* tha, u32 size) {
-    u32 mask = ~0xF;
+/**
+ * Allocates to the tail end of the Two Head Arena with guaranteed 16-byte alignment.
+ */
+void* THA_AllocTailAlign16(TwoHeadArena* tha, size_t size) {
+    uintptr_t mask = ALIGN_MASK(0x10);
 
-    tha->tail = (void*)((((u32)tha->tail & mask) - size) & (u32)(u64)mask);
+    tha->tail = (void*)((((uintptr_t)tha->tail & mask) - size) & (uintptr_t)(u64)mask);
     return tha->tail;
 }
 
-void* THA_AllocEndAlign(TwoHeadArena* tha, u32 size, u32 mask) {
-    tha->tail = (void*)((((u32)tha->tail & mask) - size) & mask);
+/**
+ * Allocates to the tail end of the Two Head Arena using the provided mask to align the allocated region.
+ *
+ * @param tha   Arena to allocate to
+ * @param size  Size of the allocation
+ * @param mask  Mask to use to align the allocated region. To align to n-bytes where n is a power of 2, use the
+ *              ALIGN_MASK(n) macro
+ *
+ * @return Pointer to the start of the allocated block
+ */
+void* THA_AllocTailAlign(TwoHeadArena* tha, size_t size, uintptr_t mask) {
+    tha->tail = (void*)((((uintptr_t)tha->tail & mask) - size) & mask);
     return tha->tail;
 }
 
-s32 THA_GetSize(TwoHeadArena* tha) {
-    return (u32)tha->tail - (u32)tha->head;
+/**
+ * Gets the remaining size of the Two Head Arena
+ *
+ * @return Remaining size. A negative number indicates an overflow.
+ */
+s32 THA_GetRemaining(TwoHeadArena* tha) {
+    return (s32)((u8*)tha->tail - (u8*)tha->head);
 }
 
+/**
+ * @return true if the Two Head Arena has overflowed, false otherwise
+ */
 u32 THA_IsCrash(TwoHeadArena* tha) {
-    return THA_GetSize(tha) < 0;
+    return THA_GetRemaining(tha) < 0;
 }
 
-void THA_Init(TwoHeadArena* tha) {
-    tha->head = tha->bufp;
-    tha->tail = (void*)((u32)tha->bufp + tha->size);
+/**
+ * Resets the head and tail positions of the Two Head Arena, all prior allocations are effectively considered free
+ * as any new allocations will begin to overwrite them.
+ */
+void THA_Reset(TwoHeadArena* tha) {
+    tha->head = tha->start;
+    tha->tail = (u8*)tha->start + tha->size;
 }
 
-void THA_Ct(TwoHeadArena* tha, void* ptr, u32 size) {
-    tha->bufp = ptr;
+/**
+ * Creates a new Two Head Arena at `start` with available size `size`
+ */
+void THA_Init(TwoHeadArena* tha, void* start, size_t size) {
+    tha->start = start;
     tha->size = size;
-    THA_Init(tha);
+    THA_Reset(tha);
 }
 
-void THA_Dt(TwoHeadArena* tha) {
+/**
+ * Destroys the Two Head Arena, no further allocations are possible
+ */
+void THA_Destroy(TwoHeadArena* tha) {
     bzero(tha, sizeof(TwoHeadArena));
 }
diff --git a/src/code/TwoHeadGfxArena.c b/src/code/TwoHeadGfxArena.c
new file mode 100644
index 0000000000..ce7b8a45fb
--- /dev/null
+++ b/src/code/TwoHeadGfxArena.c
@@ -0,0 +1,102 @@
+/**
+ * @file TwoHeadGfxArena.c
+ *
+ * This file implements a particular use of the double-ended stack allocator from TwoHeadArena.c for graphics data.
+ *
+ * Display list commands are allocated from the head while other graphics data such as matrices and vertices are
+ * allocated from the tail end.
+ *
+ * @see TwoHeadArena.c
+ */
+#include "global.h"
+
+void THGA_Init(TwoHeadGfxArena* thga, void* start, size_t size) {
+    THA_Init(&thga->tha, start, size);
+}
+
+void THGA_Destroy(TwoHeadGfxArena* thga) {
+    THA_Destroy(&thga->tha);
+}
+
+u32 THGA_IsCrash(TwoHeadGfxArena* thga) {
+    return THA_IsCrash(&thga->tha);
+}
+
+void THGA_Reset(TwoHeadGfxArena* thga) {
+    THA_Reset(&thga->tha);
+}
+
+s32 THGA_GetRemaining(TwoHeadGfxArena* thga) {
+    return THA_GetRemaining(&thga->tha);
+}
+
+Gfx* THGA_GetHead(TwoHeadGfxArena* thga) {
+    return THA_GetHead(&thga->tha);
+}
+
+void THGA_SetHead(TwoHeadGfxArena* thga, Gfx* newHead) {
+    THA_SetHead(&thga->tha, newHead);
+}
+
+void* THGA_GetTail(TwoHeadGfxArena* thga) {
+    return THA_GetTail(&thga->tha);
+}
+
+/**
+ * Allocates a display list of `num` Gfx commands to the head of the Two Head Gfx Arena.
+ */
+Gfx* THGA_AllocDisplayList(TwoHeadGfxArena* thga, size_t num) {
+    return THA_AllocHead(&thga->tha, num * sizeof(Gfx));
+}
+
+/**
+ * Allocates a single Gfx command to the head of the Two Head Gfx Arena.
+ */
+Gfx* THGA_AllocGfx(TwoHeadGfxArena* thga) {
+    return THGA_AllocDisplayList(thga, 1);
+}
+
+/**
+ * Identical to `THGA_AllocGfx`
+ *
+ * @see THGA_AllocGfx
+ */
+Gfx* THGA_AllocGfx2(TwoHeadGfxArena* thga) {
+    return THGA_AllocGfx(thga);
+}
+
+/**
+ * Allocates to the end of the Two Head Gfx Arena. Intended for data complementary to the display lists such as
+ * matrices and vertices that are only needed for a single graphics task.
+ */
+void* THGA_AllocTail(TwoHeadGfxArena* thga, size_t size) {
+    return THA_AllocTail(&thga->tha, size);
+}
+
+/**
+ * Allocates `num` matrices to the tail end of the Two Head Gfx Arena.
+ */
+Mtx* THGA_AllocMtxArray(TwoHeadGfxArena* thga, size_t num) {
+    return THGA_AllocTail(thga, num * sizeof(Mtx));
+}
+
+/**
+ * Allocates a matrix to the tail end of the Two Head Gfx Arena.
+ */
+Mtx* THGA_AllocMtx(TwoHeadGfxArena* thga) {
+    return THGA_AllocTail(thga, sizeof(Mtx));
+}
+
+/**
+ * Allocates `num` vertices to the tail end of the Two Head Gfx Arena.
+ */
+Vtx* THGA_AllocVtxArray(TwoHeadGfxArena* thga, size_t num) {
+    return THGA_AllocTail(thga, num * sizeof(Vtx));
+}
+
+/**
+ * Allocates a vertex to the tail end of the Two Head Gfx Arena.
+ */
+Vtx* THGA_AllocVtx(TwoHeadGfxArena* thga) {
+    return THGA_AllocTail(thga, sizeof(Vtx));
+}
diff --git a/src/code/game.c b/src/code/game.c
index b004dd3676..88d2f5527e 100644
--- a/src/code/game.c
+++ b/src/code/game.c
@@ -173,7 +173,7 @@ void GameState_Draw(GameState* gameState, GraphicsContext* gfxCtx) {
         DebugArena_Display();
         SystemArena_Display();
         // "%08x bytes left until the death of Hyrule (game_alloc)"
-        osSyncPrintf("ハイラル滅亡まであと %08x バイト(game_alloc)\n", THA_GetSize(&gameState->tha));
+        osSyncPrintf("ハイラル滅亡まであと %08x バイト(game_alloc)\n", THA_GetRemaining(&gameState->tha));
         R_ENABLE_ARENA_DBG = 0;
     }
 
@@ -325,10 +325,10 @@ void GameState_InitArena(GameState* gameState, size_t size) {
     osSyncPrintf("ハイラル確保 サイズ＝%u バイト\n"); // "Hyrule reserved size = %u bytes"
     arena = GameAlloc_MallocDebug(&gameState->alloc, size, "../game.c", 992);
     if (arena != NULL) {
-        THA_Ct(&gameState->tha, arena, size);
+        THA_Init(&gameState->tha, arena, size);
         osSyncPrintf("ハイラル確保成功\n"); // "Successful Hyral"
     } else {
-        THA_Ct(&gameState->tha, NULL, 0);
+        THA_Init(&gameState->tha, NULL, 0);
         osSyncPrintf("ハイラル確保失敗\n"); // "Failure to secure Hyrule"
         Fault_AddHungupAndCrash("../game.c", 999);
     }
@@ -340,10 +340,10 @@ void GameState_Realloc(GameState* gameState, size_t size) {
     u32 systemMaxFree;
     u32 systemFree;
     u32 systemAlloc;
-    void* thaBufp = gameState->tha.bufp;
+    void* thaStart = gameState->tha.start;
 
-    THA_Dt(&gameState->tha);
-    GameAlloc_Free(alloc, thaBufp);
+    THA_Destroy(&gameState->tha);
+    GameAlloc_Free(alloc, thaStart);
     osSyncPrintf("ハイラル一時解放!!\n"); // "Hyrule temporarily released!!"
     SystemArena_GetSizes(&systemMaxFree, &systemFree, &systemAlloc);
     if ((systemMaxFree - 0x10) < size) {
@@ -360,10 +360,10 @@ void GameState_Realloc(GameState* gameState, size_t size) {
     osSyncPrintf("ハイラル再確保 サイズ＝%u バイト\n", size); // "Hyral reallocate size = %u bytes"
     gameArena = GameAlloc_MallocDebug(alloc, size, "../game.c", 1033);
     if (gameArena != NULL) {
-        THA_Ct(&gameState->tha, gameArena, size);
+        THA_Init(&gameState->tha, gameArena, size);
         osSyncPrintf("ハイラル再確保成功\n"); // "Successful reacquisition of Hyrule"
     } else {
-        THA_Ct(&gameState->tha, NULL, 0);
+        THA_Init(&gameState->tha, NULL, 0);
         osSyncPrintf("ハイラル再確保失敗\n"); // "Failure to secure Hyral"
         SystemArena_Display();
         Fault_AddHungupAndCrash("../game.c", 1044);
@@ -441,7 +441,7 @@ void GameState_Destroy(GameState* gameState) {
     if (R_VI_MODE_EDIT_STATE == VI_MODE_EDIT_STATE_INACTIVE) {
         ViMode_Destroy(&sViMode);
     }
-    THA_Dt(&gameState->tha);
+    THA_Destroy(&gameState->tha);
     GameAlloc_Cleanup(&gameState->alloc);
     SystemArena_Display();
     Fault_RemoveClient(&sGameFaultClient);
@@ -467,13 +467,13 @@ void* GameState_Alloc(GameState* gameState, size_t size, char* file, s32 line) {
     if (THA_IsCrash(&gameState->tha)) {
         osSyncPrintf("ハイラルは滅亡している\n");
         ret = NULL;
-    } else if ((u32)THA_GetSize(&gameState->tha) < size) {
+    } else if ((u32)THA_GetRemaining(&gameState->tha) < size) {
         // "Hyral on the verge of extinction does not have %d bytes left (%d bytes until extinction)"
         osSyncPrintf("滅亡寸前のハイラルには %d バイトの余力もない（滅亡まであと %d バイト）\n", size,
-                     THA_GetSize(&gameState->tha));
+                     THA_GetRemaining(&gameState->tha));
         ret = NULL;
     } else {
-        ret = THA_AllocEndAlign16(&gameState->tha, size);
+        ret = THA_AllocTailAlign16(&gameState->tha, size);
         if (THA_IsCrash(&gameState->tha)) {
             osSyncPrintf("ハイラルは滅亡してしまった\n"); // "Hyrule has been destroyed"
             ret = NULL;
@@ -488,9 +488,9 @@ void* GameState_Alloc(GameState* gameState, size_t size, char* file, s32 line) {
 }
 
 void* GameState_AllocEndAlign16(GameState* gameState, size_t size) {
-    return THA_AllocEndAlign16(&gameState->tha, size);
+    return THA_AllocTailAlign16(&gameState->tha, size);
 }
 
 s32 GameState_GetArenaSize(GameState* gameState) {
-    return THA_GetSize(&gameState->tha);
+    return THA_GetRemaining(&gameState->tha);
 }
diff --git a/src/code/graph.c b/src/code/graph.c
index bbd87434cc..ba683b2670 100644
--- a/src/code/graph.c
+++ b/src/code/graph.c
@@ -93,10 +93,10 @@ void Graph_InitTHGA(GraphicsContext* gfxCtx) {
 
     pool->headMagic = GFXPOOL_HEAD_MAGIC;
     pool->tailMagic = GFXPOOL_TAIL_MAGIC;
-    THGA_Ct(&gfxCtx->polyOpa, pool->polyOpaBuffer, sizeof(pool->polyOpaBuffer));
-    THGA_Ct(&gfxCtx->polyXlu, pool->polyXluBuffer, sizeof(pool->polyXluBuffer));
-    THGA_Ct(&gfxCtx->overlay, pool->overlayBuffer, sizeof(pool->overlayBuffer));
-    THGA_Ct(&gfxCtx->work, pool->workBuffer, sizeof(pool->workBuffer));
+    THGA_Init(&gfxCtx->polyOpa, pool->polyOpaBuffer, sizeof(pool->polyOpaBuffer));
+    THGA_Init(&gfxCtx->polyXlu, pool->polyXluBuffer, sizeof(pool->polyXluBuffer));
+    THGA_Init(&gfxCtx->overlay, pool->overlayBuffer, sizeof(pool->overlayBuffer));
+    THGA_Init(&gfxCtx->work, pool->workBuffer, sizeof(pool->workBuffer));
 
     gfxCtx->polyOpaBuffer = pool->polyOpaBuffer;
     gfxCtx->polyXluBuffer = pool->polyXluBuffer;
@@ -458,20 +458,20 @@ void* Graph_Alloc(GraphicsContext* gfxCtx, size_t size) {
     TwoHeadGfxArena* thga = &gfxCtx->polyOpa;
 
     if (HREG(59) == 1) {
-        osSyncPrintf("graph_alloc siz=%d thga size=%08x bufp=%08x head=%08x tail=%08x\n", size, thga->size, thga->bufp,
+        osSyncPrintf("graph_alloc siz=%d thga size=%08x bufp=%08x head=%08x tail=%08x\n", size, thga->size, thga->start,
                      thga->p, thga->d);
     }
-    return THGA_AllocEnd(&gfxCtx->polyOpa, ALIGN16(size));
+    return THGA_AllocTail(&gfxCtx->polyOpa, ALIGN16(size));
 }
 
 void* Graph_Alloc2(GraphicsContext* gfxCtx, size_t size) {
     TwoHeadGfxArena* thga = &gfxCtx->polyOpa;
 
     if (HREG(59) == 1) {
-        osSyncPrintf("graph_alloc siz=%d thga size=%08x bufp=%08x head=%08x tail=%08x\n", size, thga->size, thga->bufp,
+        osSyncPrintf("graph_alloc siz=%d thga size=%08x bufp=%08x head=%08x tail=%08x\n", size, thga->size, thga->start,
                      thga->p, thga->d);
     }
-    return THGA_AllocEnd(&gfxCtx->polyOpa, ALIGN16(size));
+    return THGA_AllocTail(&gfxCtx->polyOpa, ALIGN16(size));
 }
 
 void Graph_OpenDisps(Gfx** dispRefs, GraphicsContext* gfxCtx, const char* file, s32 line) {
diff --git a/src/code/speed_meter.c b/src/code/speed_meter.c
index f22680b566..5d38d65bf2 100644
--- a/src/code/speed_meter.c
+++ b/src/code/speed_meter.c
@@ -231,25 +231,26 @@ void SpeedMeter_DrawAllocEntries(SpeedMeter* meter, GraphicsContext* gfxCtx, Gam
     }
 
     thga = (TwoHeadGfxArena*)&state->tha;
-    SpeedMeter_InitAllocEntry(&entry, thga->size, thga->size - THA_GetSize((TwoHeadArena*)thga),
+    //! @bug THA_GetRemaining call should be THGA_GetRemaining like the others below, harmless as-is
+    SpeedMeter_InitAllocEntry(&entry, thga->size, thga->size - THA_GetRemaining(&thga->tha),
                               GPACK_RGBA5551(0, 0, 255, 1), GPACK_RGBA5551(0, 255, 0, 1), ulx, lrx, y, y);
     SpeedMeter_DrawAllocEntry(&entry, gfxCtx);
     y++;
 
     thga = &gfxCtx->polyOpa;
-    SpeedMeter_InitAllocEntry(&entry, thga->size, thga->size - THGA_GetSize(thga), GPACK_RGBA5551(0, 0, 255, 1),
+    SpeedMeter_InitAllocEntry(&entry, thga->size, thga->size - THGA_GetRemaining(thga), GPACK_RGBA5551(0, 0, 255, 1),
                               GPACK_RGBA5551(255, 0, 255, 1), ulx, lrx, y, y);
     SpeedMeter_DrawAllocEntry(&entry, gfxCtx);
     y++;
 
     thga = &gfxCtx->polyXlu;
-    SpeedMeter_InitAllocEntry(&entry, thga->size, thga->size - THGA_GetSize(thga), GPACK_RGBA5551(0, 0, 255, 1),
+    SpeedMeter_InitAllocEntry(&entry, thga->size, thga->size - THGA_GetRemaining(thga), GPACK_RGBA5551(0, 0, 255, 1),
                               GPACK_RGBA5551(255, 255, 0, 1), ulx, lrx, y, y);
     SpeedMeter_DrawAllocEntry(&entry, gfxCtx);
     y++;
 
     thga = &gfxCtx->overlay;
-    SpeedMeter_InitAllocEntry(&entry, thga->size, thga->size - THGA_GetSize(thga), GPACK_RGBA5551(0, 0, 255, 1),
+    SpeedMeter_InitAllocEntry(&entry, thga->size, thga->size - THGA_GetRemaining(thga), GPACK_RGBA5551(0, 0, 255, 1),
                               GPACK_RGBA5551(255, 0, 0, 1), ulx, lrx, y, y);
     SpeedMeter_DrawAllocEntry(&entry, gfxCtx);
     y++;
diff --git a/src/code/z_bgcheck.c b/src/code/z_bgcheck.c
index d3223433bc..1385bbc835 100644
--- a/src/code/z_bgcheck.c
+++ b/src/code/z_bgcheck.c
@@ -149,7 +149,7 @@ void DynaSSNodeList_Initialize(PlayState* play, DynaSSNodeList* nodeList) {
  * Initialize DynaSSNodeList tbl
  */
 void DynaSSNodeList_Alloc(PlayState* play, DynaSSNodeList* nodeList, s32 max) {
-    nodeList->tbl = THA_AllocEndAlign(&play->state.tha, max * sizeof(SSNode), -2);
+    nodeList->tbl = THA_AllocTailAlign(&play->state.tha, max * sizeof(SSNode), ALIGNOF_MASK(SSNode));
 
     ASSERT(nodeList->tbl != NULL, "psst->tbl != NULL", "../z_bgcheck.c", 1811);
 
@@ -1613,9 +1613,10 @@ void BgCheck_Allocate(CollisionContext* colCtx, PlayState* play, CollisionHeader
             colCtx->subdivAmount.z = 16;
         }
     }
-    colCtx->lookupTbl = THA_AllocEndAlign(
-        &play->state.tha,
-        colCtx->subdivAmount.x * sizeof(StaticLookup) * colCtx->subdivAmount.y * colCtx->subdivAmount.z, ~1);
+    colCtx->lookupTbl = THA_AllocTailAlign(&play->state.tha,
+                                           colCtx->subdivAmount.x * sizeof(StaticLookup) * colCtx->subdivAmount.y *
+                                               colCtx->subdivAmount.z,
+                                           ALIGNOF_MASK(StaticLookup));
     if (colCtx->lookupTbl == NULL) {
         LogUtils_HungupThread("../z_bgcheck.c", 4176);
     }
@@ -2501,7 +2502,7 @@ void SSNodeList_Initialize(SSNodeList* this) {
 void SSNodeList_Alloc(PlayState* play, SSNodeList* this, s32 tblMax, s32 numPolys) {
     this->max = tblMax;
     this->count = 0;
-    this->tbl = THA_AllocEndAlign(&play->state.tha, tblMax * sizeof(SSNode), -2);
+    this->tbl = THA_AllocTailAlign(&play->state.tha, tblMax * sizeof(SSNode), ALIGNOF_MASK(SSNode));
 
     ASSERT(this->tbl != NULL, "this->short_slist_node_tbl != NULL", "../z_bgcheck.c", 5975);
 
@@ -2636,7 +2637,7 @@ void DynaPoly_NullPolyList(CollisionPoly** polyList) {
  * Allocate dyna.polyList
  */
 void DynaPoly_AllocPolyList(PlayState* play, CollisionPoly** polyList, s32 numPolys) {
-    *polyList = THA_AllocEndAlign(&play->state.tha, numPolys * sizeof(CollisionPoly), -2);
+    *polyList = THA_AllocTailAlign(&play->state.tha, numPolys * sizeof(CollisionPoly), ALIGNOF_MASK(CollisionPoly));
     ASSERT(*polyList != NULL, "ptbl->pbuf != NULL", "../z_bgcheck.c", 6247);
 }
 
@@ -2651,7 +2652,7 @@ void DynaPoly_NullVtxList(Vec3s** vtxList) {
  * Allocate dyna.vtxList
  */
 void DynaPoly_AllocVtxList(PlayState* play, Vec3s** vtxList, s32 numVtx) {
-    *vtxList = THA_AllocEndAlign(&play->state.tha, numVtx * sizeof(Vec3s), -2);
+    *vtxList = THA_AllocTailAlign(&play->state.tha, numVtx * sizeof(Vec3s), ALIGNOF_MASK(Vec3s));
     ASSERT(*vtxList != NULL, "ptbl->pbuf != NULL", "../z_bgcheck.c", 6277);
 }
 
diff --git a/src/code/z_play.c b/src/code/z_play.c
index 24311b6010..b2fd9d5aaf 100644
--- a/src/code/z_play.c
+++ b/src/code/z_play.c
@@ -393,8 +393,8 @@ void Play_Init(GameState* thisx) {
     D_801614B0.a = 0;
     Flags_UnsetAllEnv(this);
 
-    osSyncPrintf("ZELDA ALLOC SIZE=%x\n", THA_GetSize(&this->state.tha));
-    zAllocSize = THA_GetSize(&this->state.tha);
+    osSyncPrintf("ZELDA ALLOC SIZE=%x\n", THA_GetRemaining(&this->state.tha));
+    zAllocSize = THA_GetRemaining(&this->state.tha);
     zAlloc = (u32)GameState_Alloc(&this->state, zAllocSize, "../z_play.c", 2918);
     zAllocAligned = (zAlloc + 8) & ~0xF;
     ZeldaArena_Init((void*)zAllocAligned, zAllocSize - zAllocAligned + zAlloc);