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/*
* NVRAM WakeUp
* Copyright (C) 2001-2002, Sergei Haller.
*
* $Id: byteops.c 381 2003-03-18 13:44:07Z bistr-o-math $
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#define CVSREV_byteops_c \
"$Id: byteops.c 381 2003-03-18 13:44:07Z bistr-o-math $"
#include "nvram-wakeup.h"
/*
* computes the so called BCD notation of an unsigned char,
* e.g. the bcd notation of 34 is 0x34
*
* We don't check, if the conversion makes sense, i.e.
* bin2bcd(112) would return
* (112/10) << 4 + 112 % 10 =
* 11 << 4 + 2 =
* 0xB0 + 2 = 0xB2
*/
unsigned char bin2bcd( const unsigned char c ) {
return ((c / 10) << 4) + (c % 10);
}
/*
* computes the unsigned char from its so called BCD notation,
* e.g. from 0x34 to 34.
*
* We don't check, if the conversion makes sense, i.e.
* bcd2bin(0xAC) would return
* (0xAC >> 4)*10 + 0xAC & 0x0F =
* 0xA *10 + 0xC =
* 100 + 12 = 112
*/
unsigned char bcd2bin( const unsigned char c ) {
return (c >> 4)*10 + (c & 0x0F);
}
/*
* this function returns the byte stored in the bits
* sh+nr,..,sh+1
* of byte b, e.g.
* b=01011101, sh=0, nr=3
* ^^^ --> 101 --> 5 (decimal)
*/
unsigned char calculate_read( const unsigned char b,
const unsigned char nr,
const unsigned char sh) {
unsigned char msk = 255 >> (8-nr) << sh;
return (msk & b) >> sh;
}
/*
* this function returns the byte calculated by setting the bits
* sh+nr,..,sh+1
* of byte b to the bits nr,..,1 of new, e.g.
* b=01011101, sh=2, nr=4, new=00000101
* ^^^^ will be set to 0101: ^^^^
* --> 01010101
* WARNING: we do not check if new <= 2^(nr-1)
*/
unsigned char calculate_write( const unsigned char b,
const unsigned char _new,
const unsigned char nr,
const unsigned char sh) {
unsigned char msk = 255 >> (8-nr) << sh;
return (b & ~msk) | (_new << sh);;
}
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