build system refresh

rlibc/src/malloc.c

@@ -0,0 +1,74 @@
+#include <stdlib.h>
+#include <syscall.h>
+
+#define ALIGN(size) (((size) + 3) & ~3)
+#define HEADER_SIZE sizeof(struct Header)
+
+struct Header {
+    size_t size;
+    int is_free;
+    struct Header* next;
+};
+
+static struct Header* free_list_head = NULL;
+
+static struct Header* find_free_block(struct Header** last, size_t size) {
+    struct Header* current = free_list_head;
+    while (current && !(current->is_free && current->size >= size)) {
+        *last = current;
+        current = current->next;
+    }
+    return current;
+}
+
+static struct Header* request_space(struct Header* last, size_t size) {
+    struct Header* block = sbrk(0);
+    void* request = sbrk(size + HEADER_SIZE);
+    
+    if (request == (void*)-1) {
+        return NULL;
+    }
+    
+    if (last) {
+        last->next = block;
+    }
+    
+    block->size = size;
+    block->next = NULL;
+    block->is_free = 0;
+    return block;
+}
+
+void* malloc(size_t size) {
+    if (size <= 0) {
+        return NULL;
+    }
+    
+    size = ALIGN(size);
+    
+    if (free_list_head == NULL) {
+        struct Header* block = request_space(NULL, size);
+        if (!block) return NULL;
+        free_list_head = block;
+        return (void*)(block + 1);
+    }
+    
+    struct Header* last = free_list_head;
+    struct Header* block = find_free_block(&last, size);
+    
+    if (block) {
+        block->is_free = 0;
+    } else {
+        block = request_space(last, size);
+        if (!block) return NULL;
+    }
+    
+    return (void*)(block + 1);
+}
+
+void free(void* ptr) {
+    if (!ptr) return;
+    
+    struct Header* block = (struct Header*)ptr - 1;
+    block->is_free = 1;
+}