Add generic CRC calculation code

[proxmark3-svn] / include / crc.h

diff --git a/include/crc.h b/include/crc.h
new file mode 100644 (file)
index 0000000..2ee9a4d
--- /dev/null
+++ b/include/crc.h
@@ -0,0 +1,47 @@
+/*
+ * crc.h
+ *
+ * Generic CRC calculation code.
+ * 
+ */
+
+#ifndef CRC_H_
+#define CRC_H_
+
+#include <stdint.h>
+
+typedef struct crc {
+       uint32_t state;
+       int order;
+       uint32_t polynom;
+       uint32_t initial_value;
+       uint32_t final_xor;
+       uint32_t mask;
+} crc_t;
+
+/* Initialize a crc structure. order is the order of the polynom, e.g. 32 for a CRC-32
+ * polynom is the CRC polynom. initial_value is the initial value of a clean state.
+ * final_xor is XORed onto the state before returning it from crc_result(). */
+extern void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor);
+
+/* Update the crc state. data is the data of length data_width bits (only the the
+ * data_width lower-most bits are used).
+ */ 
+extern void crc_update(crc_t *crc, uint32_t data, int data_width);
+
+/* Clean the crc state, e.g. reset it to initial_value */
+extern void crc_clear(crc_t *crc);
+
+/* Get the result of the crc calculation */
+extern uint32_t crc_finish(crc_t *crc);
+
+/* Static initialization of a crc structure */
+#define CRC_INITIALIZER(_order, _polynom, _initial_value, _final_xor) { \
+       .state = ((_initial_value) & ((1L<<(_order))-1)), \
+       .order = (_order), \
+       .polynom = (_polynom), \
+       .initial_value = (_initial_value), \
+       .final_xor = (_final_xor), \
+       .mask = ((1L<<(_order))-1) }
+
+#endif /* CRC_H_ */