From 8b520b4bedda6060a7c1b1a1bd14659241a4d4c3 Mon Sep 17 00:00:00 2001
From: Greg Bowne <gbowne144@gmail.com>
Date: Thu, 8 Feb 2024 17:34:20 -0800
Subject: [PATCH] updated malloc and extended heap

---
 main.c | 70 ++++++++++++++++++++++++++++++++++------------------------
 1 file changed, 41 insertions(+), 29 deletions(-)

diff --git a/main.c b/main.c
index 753b5bc..adecd3a 100644
--- a/main.c
+++ b/main.c
@@ -4,6 +4,7 @@
 
 #define ALIGN4(s) (((((s)-1)>>2)<<2)+4)
 #define BLOCK_SIZE sizeof(struct block)
+#define MINIMUM_BLOCK_SIZE  16
 
 /// The memory block's header.
 struct block
@@ -22,22 +23,27 @@ struct block* last = NULL;
 /// @returns The new memory block.
 struct block* extend_heap(size_t s)
 {
-	struct block* b = sbrk(0);
+    struct block* b = sbrk(0);
 
-	if (sbrk(BLOCK_SIZE + s) == (void*)-1)
-		return NULL;
+    // Ensure the allocated size is at least the minimum block size
+    if (s < MINIMUM_BLOCK_SIZE) {
+        s = MINIMUM_BLOCK_SIZE;
+    }
 
-	b->size = s;
-	b->prev = last;
-	b->next = NULL;
-	b->free = 0;
+    if (sbrk(BLOCK_SIZE + s) == (void*)-1)
+        return NULL;
 
-	if (last)
-		last->next = b;
+    b->size = s;
+    b->prev = last;
+    b->next = NULL;
+    b->free =  0;
 
-	last = b;
+    if (last)
+        last->next = b;
 
-	return b;
+    last = b;
+
+    return b;
 }
 
 /// Finds the first block that will fit the given size.
@@ -73,30 +79,36 @@ struct block* fragment_block(struct block* in, size_t s)
 /// @todo Fragmenting functionality.
 void* malloc(size_t size)
 {
-	struct block* b;
+    struct block* b;
 
-	size_t alignedSize = ALIGN4(size);
+    size_t alignedSize = ALIGN4(size);
 
-	if (first)
-	{
-		b = find_first(alignedSize);
-		if (!b)
-			b = extend_heap(alignedSize);
-		else if (b->size > BLOCK_SIZE + alignedSize)
-			b = fragment_block(b, alignedSize);
-	}
-	else
-	{
-		b = extend_heap(alignedSize);
-		if (!b)
-			return NULL;
+    // Enforce the minimum block size
+    if (alignedSize < MINIMUM_BLOCK_SIZE) {
+        alignedSize = MINIMUM_BLOCK_SIZE;
+    }
 
-		first = b;
-	}
+    if (first)
+    {
+        b = find_first(alignedSize);
+        if (!b)
+            b = extend_heap(alignedSize);
+        else if (b->size > BLOCK_SIZE + alignedSize)
+            b = fragment_block(b, alignedSize);
+    }
+    else
+    {
+        b = extend_heap(alignedSize);
+        if (!b)
+            return NULL;
 
-	return b + 1;
+        first = b;
+    }
+
+    return b +  1;
 }
 
+
 /// Will flag the provided memory as free and will defragment other blocks adjacent to it.
 /// @param [in] ptr The memory to flag as free.
 /// @note If all data after the provided memory is free, it will reduce the heap size.