CHG: adjusted timing according to @sentinel 's traces

[proxmark3-svn] / common / crc16.c

diff --git a/common/crc16.c b/common/crc16.c
index a04c40127c82a996cff60985c1650ca629772c19..21310b79bbf2c882881c582656aeff002229e339 100644 (file)
--- a/common/crc16.c
+++ b/common/crc16.c
@@ -7,19 +7,19 @@
 //-----------------------------------------------------------------------------
 
 #include "crc16.h"
 //-----------------------------------------------------------------------------
 
 #include "crc16.h"

+#define CRC16_POLY_CCITT 0x1021
+#define CRC16_POLY 0x8408

 
 

-
-unsigned short update_crc16( unsigned short crc, unsigned char c )
-{
-  unsigned short i, v, tcrc = 0;
+uint16_t update_crc16( uint16_t crc, unsigned char c ) {
+  uint16_t i, v, tcrc = 0;

 
   v = (crc ^ c) & 0xff;
   for (i = 0; i < 8; i++) {
 
   v = (crc ^ c) & 0xff;
   for (i = 0; i < 8; i++) {

-      tcrc = ( (tcrc ^ v) & 1 ) ? ( tcrc >> 1 ) ^ 0x8408 : tcrc >> 1;
+      tcrc = ( (tcrc ^ v) & 1 ) ? ( tcrc >> 1 ) ^ CRC16_POLY : tcrc >> 1;

       v >>= 1;
   }
 
       v >>= 1;
   }
 

-  return ((crc >> 8) ^ tcrc)&0xffff;
+  return ((crc >> 8) ^ tcrc) & 0xffff;

 }
 
 uint16_t crc16(uint8_t const *message, int length, uint16_t remainder, uint16_t polynomial) {
 }
 
 uint16_t crc16(uint8_t const *message, int length, uint16_t remainder, uint16_t polynomial) {


@@ -27,8 +27,8 @@ uint16_t crc16(uint8_t const *message, int length, uint16_t remainder, uint16_t
        if (length == 0)
         return (~remainder);
                        
        if (length == 0)
         return (~remainder);
                        

-    for (int byte = 0; byte < length; ++byte) {
-        remainder ^= (message[byte] << 8);
+    for (uint32_t i = 0; i < length; ++i) {
+        remainder ^= (message[i] << 8);

         for (uint8_t bit = 8; bit > 0; --bit) {
             if (remainder & 0x8000) {
                 remainder = (remainder << 1) ^ polynomial;
         for (uint8_t bit = 8; bit > 0; --bit) {
             if (remainder & 0x8000) {
                 remainder = (remainder << 1) ^ polynomial;


@@ -41,9 +41,10 @@ uint16_t crc16(uint8_t const *message, int length, uint16_t remainder, uint16_t
 }
 
 uint16_t crc16_ccitt(uint8_t const *message, int length) {
 }
 
 uint16_t crc16_ccitt(uint8_t const *message, int length) {

-    return crc16(message, length, 0xffff, 0x1021);
+    return crc16(message, length, 0xffff, CRC16_POLY_CCITT);

 }
 
 }
 

-uint16_t crc16_ccitt_rev(uint8_t const *message, int length) {
-    return crc16(message, length, 0x0000, 0x1021);
-}
\ No newline at end of file
+uint16_t crc16_ccitt_kermit(uint8_t const *message, int length) {
+       uint16_t val = crc16(message, length, 0x0000, CRC16_POLY_CCITT);
+    return SwapBits(val, 16);
+}