Ndef and MAD (#801)

[proxmark3-svn] / common / crc.c

diff --git a/common/crc.c b/common/crc.c
index 90d57afab6a56c90bdfbc4b8840b718ffea247cf..b6d7551e1da4493c34a00dc1d2cb5442dc1d9736 100644 (file)
--- a/common/crc.c
+++ b/common/crc.c
@@ -5,8 +5,23 @@
 //-----------------------------------------------------------------------------
 // Generic CRC calculation code.
 //-----------------------------------------------------------------------------
-
 #include "crc.h"
+#include <stdint.h>
+#include <stddef.h>
+
+#define BITMASK(X) (1 << (X))
+
+uint32_t reflect(uint32_t v, int b) {
+    uint32_t t = v;
+    for (int i = 0; i < b; ++i) {
+        if (t & 1)
+            v |=  BITMASK((b - 1) - i);
+        else
+            v &= ~BITMASK((b - 1) - i);
+        t >>= 1;
+    }
+    return v;
+}
 
 void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor)
 {
@@ -40,3 +55,26 @@ uint32_t crc_finish(crc_t *crc)
 {
        return ( crc->state ^ crc->final_xor ) & crc->mask;
 }
+
+//credits to iceman
+uint32_t CRC8Maxim(uint8_t *buff, size_t size) 
+{
+       crc_t crc;
+       crc_init(&crc, 9, 0x8c, 0x00, 0x00);
+       crc_clear(&crc);
+
+       for (size_t i=0; i < size; ++i){
+               crc_update(&crc, buff[i], 8);
+       }
+       return crc_finish(&crc);
+}
+
+// width=8 poly=0x1d, init=0xc7 (0xe3 - WRONG! but it mentioned in MAD datasheet) refin=false  refout=false  xorout=0x00 name="CRC-8/MIFARE-MAD"
+uint32_t CRC8Mad(uint8_t *buff, size_t size) {
+    crc_t crc;
+    crc_init(&crc, 8, reflect(0x1d, 8), reflect(0xc7, 8), 0);
+    for (int i = 0; i < size; ++i)
+        crc_update(&crc, reflect(buff[i], 8), 8);
+
+    return reflect(crc_finish(&crc), 8);
+}