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Rework code for USB interface
author Daniel O'Connor <darius@dons.net.au>
date Sun, 19 Nov 2017 18:10:23 +1030
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1f3c12ba927d Rework code for USB interface
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1 INT16U cal_crc_half(INT8U far *pin, INT8U len)
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2 {
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3
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4 INT16U crc;
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5
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6 INT8U da;
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7 INT8U far *ptr;
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8 INT8U bCRCHign;
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9 INT8U bCRCLow;
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10
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11 INT16U crc_ta[16]=
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12 {
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13 0x0000,0x1021,0x2042,0x3063,0x4084,0x50a5,0x60c6,0x70e7,
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14
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15 0x8108,0x9129,0xa14a,0xb16b,0xc18c,0xd1ad,0xe1ce,0xf1ef
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16 };
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17 ptr=pin;
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18 crc=0;
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19
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20 while(len--!=0)
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21 {
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22 da=((INT8U)(crc>>8))>>4;
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23
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24 crc<<=4;
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26 crc^=crc_ta[da^(*ptr>>4)];
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27
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28 da=((INT8U)(crc>>8))>>4;
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29
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30 crc<<=4;
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32 crc^=crc_ta[da^(*ptr&0x0f)];
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33
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34 ptr++;
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35 }
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36 bCRCLow = crc;
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37
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38 bCRCHign= (INT8U)(crc>>8);
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39
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40 if(bCRCLow==0x28||bCRCLow==0x0d||bCRCLow==0x0a)
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41
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42 {
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43 bCRCLow++;
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44 }
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45 if(bCRCHign==0x28||bCRCHign==0x0d||bCRCHign==0x0a)
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46
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47 {
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48 bCRCHign++;
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49 }
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50 crc = ((INT16U)bCRCHign)<<8;
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51 crc += bCRCLow;
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52 return(crc);
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53 }