From bf9ad9cbeccb61ebb8931b30be723df9bd7b1c08 Mon Sep 17 00:00:00 2001
From: H1ghBre4k3r <h1ghbre4k3r@dev.bre4k3r.de>
Date: Tue, 13 Apr 2021 01:22:12 +0200
Subject: [PATCH] Store CRC and 'not-deleted' flag in last byte of each entry

---
 src/ens/ens_fs.c | 19 ++++++++++++++++---
 src/ens/ens_fs.h |  3 ++-
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/ens/ens_fs.c b/src/ens/ens_fs.c
index 18cee7b..c1444f6 100644
--- a/src/ens/ens_fs.c
+++ b/src/ens/ens_fs.c
@@ -1,8 +1,11 @@
 #include <drivers/flash.h>
 #include <storage/flash_map.h>
+#include <sys/crc.h>
 
 #include "ens_fs.h"
 
+#define SEED 42
+
 int ens_fs_init(ens_fs_t* fs, uint8_t id, uint64_t entry_size) {
     int rc = flash_area_open(id, &fs->area);
     if (rc) {
@@ -36,9 +39,11 @@ end:
 
 int ens_fs_write(ens_fs_t* fs, uint64_t id, void* data) {
 
-    uint64_t offset = id * fs->entry_size;
+    // Set CRC and not-deleted-flag
+    uint8_t* obj = data;
+    obj[fs->entry_size - 1] = crc7_be(SEED, obj, fs->entry_size - 1) | 1;
 
-    // TODO lome: set CRC
+    uint64_t offset = id * fs->entry_size;
     int rc = flash_area_write(fs->area, offset, data, fs->entry_size);
     if(rc) {
         goto end;
@@ -49,7 +54,15 @@ end:
 }
 
 int ens_fs_delete(ens_fs_t* fs, uint64_t id) {
-    // TODO lome: Overwrite deleted flag.
+
+    // TODO lome: Maybe overwrite last 4 bytes? Or make it file system dependend?    
+    // uint8_t data = 0;
+    // uint64_t offset = (id + 1) * fs->entry_size - 1;
+
+    // int rc = flash_area_write(fs->area, offset, &data, 0);
+    // if(rc) {
+    //     goto end;
+    // }
     return 0;
 }
 
diff --git a/src/ens/ens_fs.h b/src/ens/ens_fs.h
index e62801d..8b147ab 100644
--- a/src/ens/ens_fs.h
+++ b/src/ens/ens_fs.h
@@ -14,7 +14,8 @@ typedef struct ens_fs {
      */
     const struct flash_area* area;
     /**
-     * Size of each individual entry.
+     * Size of each individual entry. The last byte will be used by 
+     * ens_fs to store metadata about each individual entry.
      */
     size_t entry_size;
     /**