From 96224870082a0fd33010fb736528a66f5e85e6a8 Mon Sep 17 00:00:00 2001
From: jackjohn7 <70782491+jackjohn7@users.noreply.github.com>
Date: Tue, 16 Jun 2026 01:05:21 -0500
Subject: [PATCH] feat: add gdb, add some free logic

---
 nix-modules/shell.nix |  1 +
 src/jalloc.c          | 29 +++++++++++++++++++++++++----
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/nix-modules/shell.nix b/nix-modules/shell.nix
index 64ad929..47bd045 100644
--- a/nix-modules/shell.nix
+++ b/nix-modules/shell.nix
@@ -9,6 +9,7 @@
           glibc
           gcc
           gnumake
+          gdb
           clang
           clang-tools
           nixfmt
diff --git a/src/jalloc.c b/src/jalloc.c
index 7614256..30308a0 100644
--- a/src/jalloc.c
+++ b/src/jalloc.c
@@ -35,17 +35,38 @@ void *jalloc(size_t size) {
     void *ptr = heap_ptr + HEADER_SIZE;
     struct Header *hdr = (struct Header *)heap_ptr;
     struct Footer *ftr = (struct Footer *)(ptr + aligned_size);
-    if (ftr + FOOTER_SIZE > heap + sizeof(heap)) return NULL;
-    hdr->size = size;
+    if ((uint8_t *)ftr + FOOTER_SIZE > (uint8_t *)heap + sizeof(heap)) return NULL;
+    heap_ptr = (void *) ftr + FOOTER_SIZE; // set next ptr
+    if ((uint8_t *)heap_ptr > (heap + HEAP_SIZE)) heap_ptr = NULL;
+    hdr->size = aligned_size;
     hdr->next = (struct Header *)heap_ptr;
     hdr->is_free = false;
     ftr->header = hdr;
-    heap_ptr = (void *) ftr + FOOTER_SIZE; // set next ptr
     return ptr;
 }
 
 void jfree(void *ptr) {
     struct Header *hdr = (struct Header *)(ptr-HEADER_SIZE);
-    struct Footer *ftr = (struct Footer *)(hdr->next-FOOTER_SIZE);
+    struct Footer *ftr = (struct Footer *)((uint8_t *)hdr+hdr->size);
     hdr->is_free = true;
+    if ((uint8_t *)hdr > heap) { // if this is greater, then there ought to be a foot to the left
+        struct Footer *prev_ftr = (struct Footer *)((uint8_t *)hdr-FOOTER_SIZE);
+        struct Header *prev_hdr = prev_ftr->header;
+        if (prev_hdr->is_free) {
+            prev_hdr->size += hdr->size + HEADER_SIZE + FOOTER_SIZE;
+            prev_hdr->next=hdr->next;
+            ftr->header=prev_hdr;
+            hdr = prev_hdr;
+        }
+    }
+    if (hdr->next != NULL) {
+        struct Header *next_hdr = hdr->next;
+        struct Footer *next_ftr = (struct Footer *) ((uint8_t *)next_hdr + next_hdr->size);
+        if (next_hdr->is_free) {
+            hdr->size += next_hdr->size + HEADER_SIZE + FOOTER_SIZE;
+            hdr->next = (struct Header *) ((uint8_t*)next_ftr + FOOTER_SIZE);
+            next_ftr->header = hdr;
+            ftr = next_ftr;
+        }
+    }
 }