From 648504907c9f62adc72628ae73a8c668ec1276c8 Mon Sep 17 00:00:00 2001
From: iamcheeseman <dev@iamcheeseman.net>
Date: Fri, 29 May 2026 22:28:43 -0400
Subject: Generic arena allocator

Also replaces the temp allocator behind the scenes
---
 teensy/teensy_mem.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 76 insertions(+), 10 deletions(-)

(limited to 'teensy/teensy_mem.c')

diff --git a/teensy/teensy_mem.c b/teensy/teensy_mem.c
index d32cabf..cea24cb 100644
--- a/teensy/teensy_mem.c
+++ b/teensy/teensy_mem.c
@@ -1,26 +1,92 @@
 #include "teensy_mem.h"
 
+#include <string.h>
+
 #include "teensy_common.h"
 #include "teensy_list.h"
 
-#define TEMP_ALLOC_ARENA_SIZE (1024*1024)
+#define ARENA_DEFAULT_HUNK_SIZE (1<<16) // ~65KB
 
-uint8_t temp_arena[TEMP_ALLOC_ARENA_SIZE];
-uint8_t *next_temp_alloc = temp_arena;
+Arena temp_arena;
 
-void *ty_talloc(size_t size)
+static
+Arena_Hunk *create_new_hunk(size_t hunk_size)
+{
+    Arena_Hunk *hunk = ty_new(Arena_Hunk);
+    memset(hunk, 0, sizeof(Arena_Hunk));
+
+    hunk->start = ty_alloc(hunk_size);
+    hunk->end = hunk->start + hunk_size;
+    hunk->head = hunk->start;
+
+    return hunk;
+}
+
+void *ty_arena_alloc(Arena *arena, size_t size)
 {
-    if (next_temp_alloc > temp_arena + TEMP_ALLOC_ARENA_SIZE)
-        ty_log_fatal(TY_ERR_MEM, "bump up the temp alloc arena size");
+    Arena_Hunk *hunk = arena->hunks;
+    while (hunk) {
+        if (hunk->head + size < hunk->end)
+            break;
+        hunk = hunk->next;
+    }
+
+    if (!hunk) {
+        // I like these lines
+        arena->hunk_size = arena->hunk_size
+            ? arena->hunk_size : ARENA_DEFAULT_HUNK_SIZE;
+
+        hunk = create_new_hunk(arena->hunk_size);
+        hunk = create_new_hunk(arena->hunk_size);
+        hunk->next = arena->hunks;
+        arena->hunks = hunk;
+    }
+
+    void *ptr = hunk->head;
+    memset(ptr, 0, size);
+
+    hunk->head += size;
+    arena->alloced_size += size;
 
-    void *ptr = next_temp_alloc;
-    next_temp_alloc += size;
     return ptr;
 }
 
-void ty_free_temp_allocs(void)
+void ty_arena_clear(Arena *arena)
+{
+    Arena_Hunk *hunk = arena->hunks;
+    while (hunk) {
+        hunk->head = hunk->start;
+        hunk = hunk->next;
+    }
+
+    arena->alloced_size = 0;
+}
+
+void ty_arena_free(Arena *arena)
+{
+    Arena_Hunk *hunk = arena->hunks;
+    while (hunk) {
+        Arena_Hunk *next = hunk->next;
+
+        ty_free(hunk->start);
+        ty_free(hunk);
+
+        hunk = next;
+    }
+
+    arena->hunks = NULL;
+    arena->alloced_size = 0;
+}
+
+void *ty_talloc(size_t size)
+{
+    return ty_arena_alloc(&temp_arena, size);
+}
+
+void ty_clear_temp_allocs(void)
 {
-    next_temp_alloc = temp_arena;
+    ty_log_debug("%zu/%zu", temp_arena.alloced_size, temp_arena.hunk_size);
+    ty_arena_clear(&temp_arena);
 }
 
 void *ty_alloc(size_t size)
-- 
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