refactor into separate Git project

[project/fwtool.git] / crc32.h

diff --git a/crc32.h b/crc32.h
new file mode 100644 (file)
index 0000000..022c69f
--- /dev/null
+++ b/crc32.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2016 Felix Fietkau <nbd@nbd.name>
+ *
+ * Based on busybox code:
+ *   CRC32 table fill function
+ *   Copyright (C) 2006 by Rob Sullivan <cogito.ergo.cogito@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+#ifndef __BB_CRC32_H
+#define __BB_CRC32_H
+
+static inline void
+crc32_filltable(uint32_t *crc_table)
+{
+       uint32_t polynomial = 0xedb88320;
+       uint32_t c;
+       int i, j;
+
+       for (i = 0; i < 256; i++) {
+               c = i;
+               for (j = 8; j; j--)
+                       c = (c&1) ? ((c >> 1) ^ polynomial) : (c >> 1);
+
+               *crc_table++ = c;
+       }
+}
+
+static inline uint32_t
+crc32_block(uint32_t val, const void *buf, unsigned len, uint32_t *crc_table)
+{
+       const void *end = (uint8_t*)buf + len;
+
+       while (buf != end) {
+               val = crc_table[(uint8_t)val ^ *(uint8_t*)buf] ^ (val >> 8);
+               buf = (uint8_t*)buf + 1;
+       }
+       return val;
+}
+
+#endif