failed approach

gomspace/libutil/include/gs/util/crc32.h

@@ -0,0 +1,55 @@
+#ifndef GS_UTIL_CRC32_H
+#define GS_UTIL_CRC32_H
+/* Copyright (c) 2013-2017 GomSpace A/S. All rights reserved. */
+/**
+   @file
+
+   CRC32 checksumes.
+
+   https://en.wikipedia.org/wiki/Cyclic_redundancy_check.
+*/
+
+#include <gs/util/types.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+   Return init/seed value for CRC-32.
+   @return initial/seed value for CRC-32, using 0xffffffff.
+   @see gs_crc32_update(), gs_crc32_finalize()
+*/
+uint32_t gs_crc32_init(void);
+
+/**
+   Update CRC-32.
+   @param[in] crc current CRC-32
+   @param[in] block start of memory block.
+   @param[in] length length of \a block.
+   @return updated CRC-32.
+   @see gs_crc32_init(), gs_crc32_finalize()
+*/
+uint32_t gs_crc32_update(uint32_t crc, const void * block, size_t length);
+
+/**
+   Return finalized CRC-32.
+   @param[in] crc Checksum is finalized by xor'ing 0xffffffff.
+   @return finalized CRC-32.
+   @see gs_crc32_init(), gs_crc32_update()
+*/
+uint32_t gs_crc32_finalize(uint32_t crc);
+
+/**
+   Return finalized CRC-32 on amemory block.
+
+   @param[in] block block to calculate CRC-32 on.
+   @param[in] length length/size of \a block.
+   @return finalized CRC-32.
+*/
+uint32_t gs_crc32(const void *block, size_t length);
+
+#ifdef __cplusplus
+}
+#endif
+#endif