use a linked list to hold data, utilize Linux api

1 files changed, 27 insertions, 3 deletions

diff --git a/main.h b/main.h
index db38aa8..cb751d0 100644
--- a/main.h
+++ b/main.h
@@ -2,26 +2,50 @@
 #define _HELLOMAIN_H_
 
 #include <linux/cdev.h>
+#include <linux/list.h>
+
+/*
+ * Macros to aid with debugging
+ */
+#ifdef HELLO_DEBUG
+  #define PDEBUG(fmt, args...) printk( KERN_DEBUG "[hello] " fmt, ##args)
+#else
+  #define PDEBUG(fmt, args...) /* not debugging: nothing */
+#endif
 
 #ifndef HELLO_MAJOR
 #define HELLO_MAJOR 0 /* let kernel choose, unless user really defined it */
 #endif
 
-#define HELLO_KERNEL_BUFF_LEN 1024
+/*
+ * Allow user to define size of node using a #define, or passing -D compiler
+ * flag
+ */
+#ifndef HELLO_NODE_CHUNK_SIZE
+#define HELLO_NODE_CHUNK_SIZE 256
+#endif
 
 extern int hello_major;
 extern int hello_minor;
 
 extern char *magicstr;
 
+/* node to be used with Linux api for circular linked lists */
+struct hello_ll
+{
+    char *chunk;
+    struct list_head list;
+};
+
 struct hello_dev {
     dev_t devnum;
     struct semaphore sem;
     struct cdev cdev; /* char device */
 
     /* for r/w operations */
-    char hello_buffer[HELLO_KERNEL_BUFF_LEN];
-    size_t buff_index;
+    struct hello_ll *mylist;
+    int chunk_sz;
+    size_t ll_size;
 };
 
 /* function prototypes */