From 2c0efd93530c472e96ff3529aee983b53f3b78d9 Mon Sep 17 00:00:00 2001
From: Nathan Lee <me@nwlee.tech>
Date: Wed, 12 Aug 2026 17:44:17 -0500
Subject: rework project structure

---
 kernel/common/mem.c | 116 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 116 insertions(+)
 create mode 100644 kernel/common/mem.c

(limited to 'kernel/common/mem.c')

diff --git a/kernel/common/mem.c b/kernel/common/mem.c
new file mode 100644
index 0000000..fee0761
--- /dev/null
+++ b/kernel/common/mem.c
@@ -0,0 +1,116 @@
+#include <sys/mem.h>
+#include <early/dtb.h>
+
+static struct page *free_list;
+
+static void merge_freelist() {
+    struct page *list = free_list;
+
+    while (list && list->next) {
+        if ((void*)list + list->size == list->next) {
+            list->size += list->next->size;
+            list->next = list->next->next;
+            continue;
+        }
+        list = list->next;
+    }
+}
+
+void* kmalloc(size_t size) {
+    struct page *page = free_list;
+    struct page *last = NULL;
+
+    size_t combined_size = size + sizeof(struct page);
+
+    while (page && page->size < combined_size) {
+        last = page;
+        page = page->next;
+    }
+
+    if (page == NULL)
+        return NULL;
+
+
+    if (page->size - combined_size < sizeof(struct page)) {
+        // Return the entire page
+        if (last)
+            last->next = page->next;
+        else
+            free_list = page->next;
+
+    } else {
+        // break page and create a new one
+        struct page *broken = (void *)page + combined_size;
+        broken->size = page->size - combined_size;
+        broken->next = page->next;
+        broken->status = MEMPAGE_FREE;
+
+        page->size = combined_size;
+        page->next = broken;
+
+        if (last)
+            last->next = broken;
+        else
+            free_list = broken;
+    } 
+
+    page->status = MEMPAGE_USED;
+
+    return (void *)page + sizeof(struct page);
+}
+
+void* kzalloc(size_t size) {
+    char *ptr = kmalloc(size);
+
+    if (!ptr)
+        return NULL;
+
+    for (size_t i = 0; i < size; i++) {
+        *(ptr + i) = 0;
+    }
+
+    return ptr;
+}
+
+void kfree(void *ptr) {
+    if (!ptr)
+        return;
+
+    struct page *page_info = (struct page *)(ptr - sizeof(struct page));
+    struct page *iter = free_list;
+
+    page_info->status = MEMPAGE_FREE;
+
+    if (!iter) {
+        free_list = page_info;
+        page_info->next = NULL;
+        goto merge;
+    }
+    if (page_info < free_list) {
+        page_info->next = iter;
+        free_list = page_info;
+        goto merge;
+    }
+
+    while (iter->next && iter->next < page_info) {
+        iter = iter->next;
+    }
+
+    page_info->next = iter->next;
+    iter->next = page_info;
+
+    merge:
+    merge_freelist();
+}
+
+
+void km_init(struct mem_info *info) {
+    struct page *base = (struct page *)info->start;
+    base->next = NULL;
+    base->size = info->size - sizeof(struct page);
+    base->status = MEMPAGE_FREE;
+
+    free_list = base;
+}
+
+
-- 
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