78 lines
2.1 KiB
C
78 lines
2.1 KiB
C
//-----------------------------------------------------------------------------
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// This code is licensed to you under the terms of the GNU GPL, version 2 or,
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// at your option, any later version. See the LICENSE.txt file for the text of
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// the license.
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//-----------------------------------------------------------------------------
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// ISO15693 CRC & other commons
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//-----------------------------------------------------------------------------
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#include "iso15693tools.h"
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// The CRC as described in ISO 15693-Part 3-Annex C
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uint16_t Iso15693Crc(uint8_t *d, size_t n){
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init_table(CRC_15);
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return crc16_x25(d, n);
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}
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// adds a CRC to a dataframe
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// d[] iso15963 frame without crc
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// n length without crc
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// returns the new length of the dataframe.
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int Iso15693AddCrc(uint8_t *d, size_t n) {
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uint16_t crc = Iso15693Crc(d, n);
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d[n] = crc & 0xff;
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d[n+1] = crc >> 8;
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return n + 2;
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}
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// check the CRC as described in ISO 15693-Part 3-Annex C
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// v buffer with data
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// n length (including crc)
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// If calculated with crc bytes, the residue should be 0xF0B8
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bool Iso15693CheckCrc(uint8_t *d, size_t n) {
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return (Iso15693Crc(d, n) == ISO15_CRC_CHECK );
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}
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int sprintf(char *str, const char *format, ...);
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// returns a string representation of the UID
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// UID is transmitted and stored LSB first, displayed MSB first
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// target char* buffer, where to put the UID, if NULL a static buffer is returned
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// uid[] the UID in transmission order
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// return: ptr to string
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char* Iso15693sprintUID(char *target, uint8_t *uid) {
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static char tempbuf[2*8+1] = {0};
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if (target == NULL)
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target = tempbuf;
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sprintf(target, "%02X %02X %02X %02X %02X %02X %02X %02X",
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uid[7], uid[6], uid[5], uid[4],
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uid[3], uid[2], uid[1], uid[0]
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);
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return target;
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}
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uint16_t iclass_crc16(uint8_t *d, uint16_t n) {
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unsigned int data;
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uint16_t crc = 0xffff;
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if (n == 0)
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return (~crc);
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do {
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for (uint8_t i=0, data = *d++; i < 8; i++, data >>= 1) {
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if ((crc & 0x0001) ^ (data & 0x0001))
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crc = (crc >> 1) ^ ISO15_CRC_POLY;
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else
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crc >>= 1;
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}
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} while (--n);
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crc = ~crc;
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data = crc;
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crc = (crc << 8) | (data >> 8 & 0xff);
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crc = crc ^ 0xBC3;
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return crc;
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} |