## File: byteops.c

package info (click to toggle)
nvram-wakeup 1.1-4
 `12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182838485` ``````/* * 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);; } ``````