root / arduino-1.0 / hardware / arduino / cores / arduino / wiring_shift.c @ 58d82c77
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1 | 58d82c77 | Tom Mullins | /*
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2 | wiring_shift.c - shiftOut() function
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3 | Part of Arduino - http://www.arduino.cc/
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4 | |||
5 | Copyright (c) 2005-2006 David A. Mellis
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6 | |||
7 | This library is free software; you can redistribute it and/or
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8 | modify it under the terms of the GNU Lesser General Public
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9 | License as published by the Free Software Foundation; either
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10 | version 2.1 of the License, or (at your option) any later version.
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11 | |||
12 | This library is distributed in the hope that it will be useful,
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13 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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15 | Lesser General Public License for more details.
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16 | |||
17 | You should have received a copy of the GNU Lesser General
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18 | Public License along with this library; if not, write to the
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19 | Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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20 | Boston, MA 02111-1307 USA
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21 | |||
22 | $Id: wiring.c 248 2007-02-03 15:36:30Z mellis $
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23 | */
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24 | |||
25 | #include "wiring_private.h" |
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26 | |||
27 | uint8_t shiftIn(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder) { |
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28 | uint8_t value = 0;
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29 | uint8_t i; |
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30 | |||
31 | for (i = 0; i < 8; ++i) { |
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32 | digitalWrite(clockPin, HIGH); |
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33 | if (bitOrder == LSBFIRST)
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34 | value |= digitalRead(dataPin) << i; |
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35 | else
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36 | value |= digitalRead(dataPin) << (7 - i);
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37 | digitalWrite(clockPin, LOW); |
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38 | } |
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39 | return value;
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40 | } |
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41 | |||
42 | void shiftOut(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder, uint8_t val)
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43 | { |
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44 | uint8_t i; |
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45 | |||
46 | for (i = 0; i < 8; i++) { |
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47 | if (bitOrder == LSBFIRST)
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48 | digitalWrite(dataPin, !!(val & (1 << i)));
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49 | else
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50 | digitalWrite(dataPin, !!(val & (1 << (7 - i)))); |
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51 | |||
52 | digitalWrite(clockPin, HIGH); |
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53 | digitalWrite(clockPin, LOW); |
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54 | } |
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55 | } |