Restructured the major interfaces of the filesystem

1 files changed, 27 insertions, 0 deletions

diff --git a/lfs_util.c b/lfs_util.c
new file mode 100644
index 0000000..9b0f66b
--- /dev/null
+++ b/lfs_util.c
@@ -0,0 +1,27 @@
+/*
+ * lfs util functions
+ *
+ * Copyright (c) 2017 Christopher Haster
+ * Distributed under the MIT license
+ */
+#include "lfs_util.h"
+
+
+uint32_t lfs_crc(const void *buffer, lfs_size_t size, uint32_t crc) {
+    static const uint32_t rtable[16] = {
+        0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
+        0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
+        0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
+        0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c,
+    };
+
+    const uint8_t *data = buffer;
+
+    for (lfs_size_t i = 0; i < size; i++) {
+        crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 0)) & 0xf];
+        crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 4)) & 0xf];
+    }
+
+    return crc;
+}
+