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Fixed TransportCRC compatibility with CRC-16-CCITT

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This commit is contained in:
Pavel Kirienko
2014-02-26 09:45:06 +04:00
parent a6ab9c416f
commit 887ee64d54
3 changed files with 39 additions and 26 deletions
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libuavcan/include/uavcan/internal/transport/crc.hpp
+24 -6
View File
@@ -4,6 +4,7 @@
#pragma once
#include <cassert>
#include <stdint.h>
namespace uavcan
@@ -11,8 +12,16 @@ namespace uavcan
/**
* CRC-16-CCITT
* Initial value: 0x0000
* Coefficient: 0x1021
* Initial value: 0xFFFF
* Poly: 0x1021
* Reverse: no
* Output xor: 0
*
* import crcmod
* crc = crcmod.predefined.Crc('crc-ccitt-false')
* crc.update('123456789')
* crc.hexdigest()
* '29B1'
*/
class TransportCRC
{
@@ -23,17 +32,26 @@ public:
enum { NumBytes = 2 };
TransportCRC()
: value_(0x0000)
: value_(0xFFFF)
{ }
TransportCRC(const uint8_t* bytes, unsigned int len)
: value_(0x0000)
: value_(0xFFFF)
{
add(bytes, len);
}
uint16_t add(uint8_t byte);
uint16_t add(const uint8_t* bytes, unsigned int len);
void add(uint8_t byte)
{
value_ = ((value_ << 8) ^ Table[((value_ >> 8) ^ byte) & 0xFF]) & 0xFFFF;
}
void add(const uint8_t* bytes, unsigned int len)
{
assert(bytes);
while (len--)
add(*bytes++);
}
uint16_t get() const { return value_; }
};