Add CRC16 with reverse bit order
This commit is contained in:
Nils Faerber
parent
5c3d6461a1
commit
0d6cba4530
5 changed files with 450 additions and 4 deletions
2
Makefile
2
Makefile
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@ -5,7 +5,7 @@ CFLAGS = $(CCFLAGS)
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PRGNAME = metawatch
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MEMBERS = metawatch
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MEMBERS = metawatch crc16ccitt
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# no need to change anything below this line
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# ------------------------------------------
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367
crc16ccitt.c
Normal file
367
crc16ccitt.c
Normal file
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@ -0,0 +1,367 @@
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/*
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* derived from crctester.c
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* original header:
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* ----------------------------------------------------------------------------
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* CRC tester v1.3 written on 4th of February 2003 by Sven Reifegerste (zorc/reflex)
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* This is the complete compilable C program, consisting only of this .c file.
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* No guarantee for any mistakes.
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*
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* changes to CRC tester v1.2:
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*
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* - remove unneccessary (!(polynom&1)) test for invalid polynoms
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* (now also XMODEM parameters 0x8408 work in c-code as they should)
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*
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* changes to CRC tester v1.1:
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*
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* - include an crc&0crcmask after converting non-direct to direct initial
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* value to avoid overflow
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*
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* changes to CRC tester v1.0:
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*
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* - most int's were replaced by unsigned long's to allow longer input strings
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* and avoid overflows and unnecessary type-casting's
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* ----------------------------------------------------------------------------
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*/
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static const int order = 16;
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static const unsigned long polynom = 0x1021;
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static const int direct = 1;
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static const unsigned long crcinit = 0xffff;
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static const unsigned long crcxor = 0x0000;
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static const int refin = 1;
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static const int refout = 0;
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// 'order' [1..32] is the CRC polynom order, counted without the leading '1' bit
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// 'polynom' is the CRC polynom without leading '1' bit
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// 'direct' [0,1] specifies the kind of algorithm: 1=direct, no augmented zero bits
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// 'crcinit' is the initial CRC value belonging to that algorithm
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// 'crcxor' is the final XOR value
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// 'refin' [0,1] specifies if a data byte is reflected before processing (UART) or not
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// 'refout' [0,1] specifies if the CRC will be reflected before XOR
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// internal global values:
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static unsigned long crcmask;
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static unsigned long crchighbit;
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static unsigned long crcinit_direct;
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static unsigned long crcinit_nondirect;
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static unsigned long crctab[256];
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// subroutines
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static unsigned long reflect (unsigned long crc, int bitnum) {
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// reflects the lower 'bitnum' bits of 'crc'
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unsigned long i, j=1, crcout=0;
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for (i=(unsigned long)1<<(bitnum-1); i; i>>=1) {
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if (crc & i) crcout|=j;
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j<<= 1;
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}
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return (crcout);
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}
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static void generate_crc_table(void)
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{
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// make CRC lookup table used by table algorithms
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int i, j;
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unsigned long bit, crc;
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for (i=0; i<256; i++) {
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crc=(unsigned long)i;
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if (refin) crc=reflect(crc, 8);
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crc<<= order-8;
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for (j=0; j<8; j++) {
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bit = crc & crchighbit;
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crc<<= 1;
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if (bit) crc^= polynom;
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}
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if (refin) crc = reflect(crc, order);
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crc&= crcmask;
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crctab[i]= crc;
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}
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}
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static unsigned long crctablefast (unsigned char* p, unsigned long len)
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{
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// fast lookup table algorithm without augmented zero bytes, e.g. used in pkzip.
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// only usable with polynom orders of 8, 16, 24 or 32.
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unsigned long crc = crcinit_direct;
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if (refin) crc = reflect(crc, order);
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if (!refin) while (len--) crc = (crc << 8) ^ crctab[ ((crc >> (order-8)) & 0xff) ^ *p++];
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else while (len--) crc = (crc >> 8) ^ crctab[ (crc & 0xff) ^ *p++];
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if (refout^refin) crc = reflect(crc, order);
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crc^= crcxor;
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crc&= crcmask;
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return(crc);
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}
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static unsigned long crctable (unsigned char* p, unsigned long len)
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{
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// normal lookup table algorithm with augmented zero bytes.
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// only usable with polynom orders of 8, 16, 24 or 32.
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unsigned long crc = crcinit_nondirect;
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if (refin)
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crc = reflect(crc, order);
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if (!refin)
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while (len--)
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crc = ((crc << 8) | *p++) ^ crctab[ (crc >> (order-8)) & 0xff];
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else
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while (len--)
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crc = ((crc >> 8) | (*p++ << (order-8))) ^ crctab[ crc & 0xff];
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if (!refin)
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while (++len < order/8)
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crc = (crc << 8) ^ crctab[ (crc >> (order-8)) & 0xff];
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else
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while (++len < order/8)
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crc = (crc >> 8) ^ crctab[crc & 0xff];
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if (refout^refin)
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crc = reflect(crc, order);
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crc^= crcxor;
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crc&= crcmask;
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return(crc);
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}
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unsigned long crcbitbybit(unsigned char* p, unsigned long len) {
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// bit by bit algorithm with augmented zero bytes.
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// does not use lookup table, suited for polynom orders between 1...32.
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unsigned long i, j, c, bit;
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unsigned long crc = crcinit_nondirect;
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for (i=0; i<len; i++) {
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c = (unsigned long)*p++;
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if (refin)
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c = reflect(c, 8);
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for (j=0x80; j; j>>=1) {
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bit = crc & crchighbit;
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crc<<= 1;
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if (c & j)
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crc|= 1;
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if (bit)
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crc^= polynom;
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}
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}
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for (i=0; i<order; i++) {
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bit = crc & crchighbit;
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crc <<= 1;
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if (bit)
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crc^= polynom;
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}
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if (refout)
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crc=reflect(crc, order);
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crc ^= crcxor;
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crc &= crcmask;
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return(crc);
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}
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unsigned long crcbitbybitfast(unsigned char* p, unsigned long len) {
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// fast bit by bit algorithm without augmented zero bytes.
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// does not use lookup table, suited for polynom orders between 1...32.
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unsigned long i, j, c, bit;
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unsigned long crc = crcinit_direct;
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for (i=0; i<len; i++) {
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c = (unsigned long)*p++;
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if (refin)
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c = reflect(c, 8);
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for (j=0x80; j; j>>=1) {
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bit = crc & crchighbit;
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crc <<= 1;
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if (c & j)
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bit^= crchighbit;
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if (bit)
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crc^= polynom;
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}
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}
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if (refout)
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crc=reflect(crc, order);
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crc^= crcxor;
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crc&= crcmask;
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return(crc);
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}
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void crc16ccitt_init(void)
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{
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int i;
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unsigned long bit, crc;
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crcmask = ((((unsigned long)1<<(order-1))-1)<<1)|1;
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crchighbit = (unsigned long)1<<(order-1);
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generate_crc_table();
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if (!direct) {
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crcinit_nondirect = crcinit;
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crc = crcinit;
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for (i=0; i<order; i++) {
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bit = crc & crchighbit;
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crc <<= 1;
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if (bit)
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crc^= polynom;
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}
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crc &= crcmask;
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crcinit_direct = crc;
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} else {
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crcinit_direct = crcinit;
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crc = crcinit;
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for (i=0; i<order; i++) {
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bit = crc & 1;
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if (bit)
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crc^= polynom;
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crc >>= 1;
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if (bit)
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crc|= crchighbit;
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}
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crcinit_nondirect = crc;
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}
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}
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unsigned short crc16ccitt (unsigned char *data, int len)
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{
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// call CRC algorithms using the CRC parameters above and print result to the console
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return crcbitbybitfast((unsigned char *)data, len);
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}
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#if 0
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int main() {
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// test program for checking four different CRC computing types that are:
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// crcbit(), crcbitfast(), crctable() and crctablefast(), see above.
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// parameters are at the top of this program.
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// Result will be printed on the console.
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int i;
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unsigned long bit, crc;
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// at first, compute constant bit masks for whole CRC and CRC high bit
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crcmask = ((((unsigned long)1<<(order-1))-1)<<1)|1;
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crchighbit = (unsigned long)1<<(order-1);
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// check parameters
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if (order < 1 || order > 32) {
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printf("ERROR, invalid order, it must be between 1..32.\n");
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return(0);
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}
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if (polynom != (polynom & crcmask)) {
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printf("ERROR, invalid polynom.\n");
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return(0);
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}
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if (crcinit != (crcinit & crcmask)) {
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printf("ERROR, invalid crcinit.\n");
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return(0);
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}
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if (crcxor != (crcxor & crcmask)) {
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printf("ERROR, invalid crcxor.\n");
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return(0);
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}
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// generate lookup table
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generate_crc_table();
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// compute missing initial CRC value
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if (!direct) {
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crcinit_nondirect = crcinit;
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crc = crcinit;
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for (i=0; i<order; i++) {
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bit = crc & crchighbit;
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crc<<= 1;
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if (bit) crc^= polynom;
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}
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crc&= crcmask;
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crcinit_direct = crc;
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}
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else {
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crcinit_direct = crcinit;
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crc = crcinit;
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for (i=0; i<order; i++) {
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bit = crc & 1;
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if (bit) crc^= polynom;
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crc >>= 1;
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if (bit) crc|= crchighbit;
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}
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crcinit_nondirect = crc;
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}
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// call CRC algorithms using the CRC parameters above and print result to the console
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printf("\n");
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printf("CRC tester v1.1 written on 13/01/2003 by Sven Reifegerste (zorc/reflex)\n");
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printf("-----------------------------------------------------------------------\n");
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printf("\n");
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printf("Parameters:\n");
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printf("\n");
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printf(" polynom : 0x%x\n", polynom);
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printf(" order : %d\n", order);
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printf(" crcinit : 0x%x direct, 0x%x nondirect\n", crcinit_direct, crcinit_nondirect);
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printf(" crcxor : 0x%x\n", crcxor);
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printf(" refin : %d\n", refin);
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printf(" refout : %d\n", refout);
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printf("\n");
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printf(" data string : '%s' (%d bytes)\n", string, strlen(string));
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printf("\n");
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printf("Results:\n");
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printf("\n");
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printf(" crc bit by bit : 0x%x\n", crcbitbybit((unsigned char *)string, strlen(string)));
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printf(" crc bit by bit fast : 0x%x\n", crcbitbybitfast((unsigned char *)string, strlen(string)));
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if (!(order&7)) printf(" crc table : 0x%x\n", crctable((unsigned char *)string, strlen(string)));
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if (!(order&7)) printf(" crc table fast : 0x%x\n", crctablefast((unsigned char *)string, strlen(string)));
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return(0);
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}
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#endif
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7
crc16ccitt.h
Normal file
7
crc16ccitt.h
Normal file
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@ -0,0 +1,7 @@
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#ifndef _CRC16_h
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#define _CRC16_H
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void crc16ccitt_init(void);
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unsigned short crc16ccitt (unsigned char *data, int len);
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#endif
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73
metawatch.c
73
metawatch.c
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@ -7,23 +7,90 @@
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <string.h>
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#include <time.h>
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#include "metawatch_protocol.h"
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#include "crc16ccitt.h"
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void dump_frame(unsigned char *frame, int len)
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{
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int i;
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for (i=0; i<len; i++)
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fprintf(stderr, "0x%02x ", frame[i]);
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fprintf(stderr, "\n");
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}
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void mw_send_packet(int mw_fd, unsigned char msg_type, unsigned char options, unsigned char *data, unsigned char len)
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{
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unsigned short crc;
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unsigned char frame[64];
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memset(frame, 0, 64);
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frame[0] = MW_SOF;
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frame[1] = len + 6;
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frame[2] = msg_type;
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frame[3] = options;
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memcpy(frame+4, data, len);
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crc = crc16ccitt(frame, len+4);
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*(unsigned short *)(frame+len+4) = crc;
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dump_frame(frame, len+6);
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write(mw_fd, frame, len+6);
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}
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void mw_set_rtc(int mw_fd, unsigned char clk1224, unsigned char date_fmt)
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{
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time_t mtime;
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struct tm mtm;
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unsigned short year;
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unsigned char data[32];
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mtime = time(NULL);
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localtime_r(&mtime, &mtm);
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year = mtm.tm_year + 1900;
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data[0] = (year & 0x0f00) >> 8;
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data[1] = (year & 0x00ff);
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data[2] = mtm.tm_mon + 1;
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data[3] = mtm.tm_mday;
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data[4] = mtm.tm_wday;
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data[5] = mtm.tm_hour;
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data[6] = mtm.tm_min;
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data[7] = mtm.tm_sec;
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data[8] = clk1224;
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data[9] = date_fmt;
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mw_send_packet(mw_fd, MW_SET_REAL_TIME_CLOCK, 0, data, 10);
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}
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int main(int argc, char **argv)
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{
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int mwfd;
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int mw_fd;
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if (argc != 2) {
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fprintf(stderr, "Usage:\n\t%s <devicename>\n", argv[0]);
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return 1;
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};
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mwfd = open(argv[1], O_RDWR);
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if (mwfd < 0) {
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crc16ccitt_init();
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mw_fd = open(argv[1], O_RDWR);
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if (mw_fd < 0) {
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perror("open");
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return 1;
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};
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mw_set_rtc(mw_fd, MW_RTC_CLOCK_24HR, MW_RTC_DATE_DDMM);
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fsync(mw_fd);
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close(mw_fd);
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return 0;
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};
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@ -15,6 +15,11 @@
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#define MW_GET_REAL_TIME_CLOCK 0x27
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#define MW_GET_REAL_TIME_CLOCK_RSP 0x28
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#define MW_RTC_CLOCK_12HR 0x00
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#define MW_RTC_CLOCK_24HR 0x01
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#define MW_RTC_DATE_MMDD 0x00
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#define MW_RTC_DATE_DDMM 0x01
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#define MW_RESERVED 0x32
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#define MW_STATUS_CHANGE_EVENT 0x33
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#define MW_BUTTON_EVENT_MESSAGE 0x34
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