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83 lines (80 loc) · 2.35 KB
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/*
* @file shiftIn.c
*
* @author Andy Lindsay
*
* @version 0.85
*
* @copyright Copyright (C) Parallax, Inc. 2012. See end of file for
* terms of use (MIT License).
*
* @brief shiftIn function source, see simpletools.h for documentation.
*
* @detail Please submit bug reports, suggestions, and improvements to
* this code to editor@parallax.com.
*/
#include "simpletools.h" // simpletools function prototypes
// shiftIn function definition
int shift_in(int pinDat, int pinClk, int mode, int bits)
{
int vi, vf, inc;
int value = 0;
int preflag = 0;
if((mode == MSBPRE)||(mode == LSBPRE)) preflag = 1;
switch(mode)
{
case MSBPRE:
vi = bits - 1;
vf = -1;
inc = -1;
//value |= (input(pinDat) << bits);
break;
case LSBPRE:
vi = 0;
vf = bits;
inc = 1;
value |= input(pinDat);
break;
case MSBPOST:
vi = bits -1;
vf = -1;
inc = -1;
break;
default: // case LSBPOST:
vi = 0;
vf = bits;
inc = 1;
break;
}
low(pinClk);
int i;
for(i = vi; i != vf; i += inc)
{
if(preflag) value |= (input(pinDat) << i);
toggle(pinClk);
toggle(pinClk);
if(!preflag) value |= (input(pinDat) << i);
}
return value;
}
/**
* TERMS OF USE: MIT License
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/