Pridana verze v0.1

kernel/memory.c

@@ -0,0 +1,106 @@
+/*
+ * AsterOS Kernel
+ * Autor: Pavel Kalaš
+ * Rok: 2026
+ *
+ */
+
+/*
+ * Tento modul realizuje dve vrstvy spravy pameti jadra.
+ * Prvni cast je bitmap allocator fyzickych stranek pro page_alloc/page_free,
+ * druha cast je jednoducha linearni heap alokace pro kernelove objekty.
+ */
+
+#include "memory.h"
+#include "string.h"
+
+#define PMM_MAX_MEMORY (64ULL * 1024ULL * 1024ULL)
+#define PMM_MAX_PAGES  (PMM_MAX_MEMORY / PAGE_SIZE)
+#define PMM_BITMAP_SIZE (PMM_MAX_PAGES / 8)
+
+static u8 page_bitmap[PMM_BITMAP_SIZE];
+static usize free_pages = PMM_MAX_PAGES;
+
+#define KHEAP_SIZE (1024 * 1024)
+static u8 kernel_heap[KHEAP_SIZE];
+static usize heap_offset = 0;
+
+static void bitmap_set(usize idx) {
+    page_bitmap[idx / 8] |= (u8)(1u << (idx % 8));
+}
+
+static void bitmap_clear(usize idx) {
+    page_bitmap[idx / 8] &= (u8)~(1u << (idx % 8));
+}
+
+static int bitmap_test(usize idx) {
+    return (page_bitmap[idx / 8] & (u8)(1u << (idx % 8))) != 0;
+}
+
+void memory_init(void) {
+    aster_memset(page_bitmap, 0, PMM_BITMAP_SIZE);
+    free_pages = PMM_MAX_PAGES;
+    heap_offset = 0;
+
+    for (usize i = 0; i < 256; ++i) {
+        bitmap_set(i);
+        --free_pages;
+    }
+}
+
+void *page_alloc(void) {
+    usize i;
+
+    for (i = 0; i < PMM_MAX_PAGES; ++i) {
+        if (!bitmap_test(i)) {
+            bitmap_set(i);
+            --free_pages;
+            return (void *)(i * PAGE_SIZE);
+        }
+    }
+
+    return 0;
+}
+
+void page_free(void *page) {
+    usize idx;
+
+    if (!page) {
+        return;
+    }
+
+    idx = ((usize)page) / PAGE_SIZE;
+    if (idx < PMM_MAX_PAGES && bitmap_test(idx)) {
+        bitmap_clear(idx);
+        ++free_pages;
+    }
+}
+
+void *kmalloc(usize size) {
+    usize aligned;
+
+    if (size == 0) {
+        return 0;
+    }
+
+    aligned = (size + 15) & ~((usize)15);
+    if (heap_offset + aligned > KHEAP_SIZE) {
+        return 0;
+    }
+
+    void *ptr = &kernel_heap[heap_offset];
+    heap_offset += aligned;
+    return ptr;
+}
+
+void kfree(void *ptr) {
+    (void)ptr;
+}
+
+usize memory_total_pages(void) {
+    return PMM_MAX_PAGES;
+}
+
+usize memory_free_pages(void) {
+    return free_pages;
+}