tools/ucl/src/getbit.h

   1 /* getbit.h -- bit-buffer access
   2
   3    This file is part of the UCL data compression library.
   4
   5    Copyright (C) 1996-2002 Markus Franz Xaver Johannes Oberhumer
   6    All Rights Reserved.
   7
   8    The UCL library is free software; you can redistribute it and/or
   9    modify it under the terms of the GNU General Public License as
  10    published by the Free Software Foundation; either version 2 of
  11    the License, or (at your option) any later version.
  12
  13    The UCL library is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with the UCL library; see the file COPYING.
  20    If not, write to the Free Software Foundation, Inc.,
  21    59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  22
  23    Markus F.X.J. Oberhumer
  24    <markus@oberhumer.com>
  25    http://www.oberhumer.com/opensource/ucl/
  26  */
  27
  28
  29 /***********************************************************************
  30 //
  31 ************************************************************************/
  32
  33 #if 1
  34 #define getbit_8(bb, src, ilen) \
  35     (((bb = bb & 0x7f ? bb*2 : ((unsigned)src[ilen++]*2+1)) >> 8) & 1)
  36 #elif 1
  37 #define getbit_8(bb, src, ilen) \
  38     (bb*=2,bb&0xff ? (bb>>8)&1 : ((bb=src[ilen++]*2+1)>>8)&1)
  39 #else
  40 #define getbit_8(bb, src, ilen) \
  41     (((bb*=2, (bb&0xff ? bb : (bb=src[ilen++]*2+1,bb))) >> 8) & 1)
  42 #endif
  43
  44
  45 #define getbit_le16(bb, src, ilen) \
  46     (bb*=2,bb&0xffff ? (bb>>16)&1 : (ilen+=2,((bb=(src[ilen-2]+src[ilen-1]*256u)*2+1)>>16)&1))
  47
  48
  49 #if 1 && defined(UCL_UNALIGNED_OK_4) && (UCL_BYTE_ORDER == UCL_LITTLE_ENDIAN)
  50 #define getbit_le32(bb, bc, src, ilen) \
  51     (bc > 0 ? ((bb>>--bc)&1) : (bc=31,\
  52     bb=*(const ucl_uint32p)((src)+ilen),ilen+=4,(bb>>31)&1))
  53 #else
  54 #define getbit_le32(bb, bc, src, ilen) \
  55     (bc > 0 ? ((bb>>--bc)&1) : (bc=31,\
  56     bb=src[ilen]+src[ilen+1]*0x100+src[ilen+2]*UCL_UINT32_C(0x10000)+src[ilen+3]*UCL_UINT32_C(0x1000000),\
  57     ilen+=4,(bb>>31)&1))
  58 #endif
  59
  60
  61 /*
  62 vi:ts=4:et
  63 */
  64