firmware/hotswap.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2004 by Jens Arnold
  11  *
  12  * All files in this archive are subject to the GNU General Public License.
  13  * See the file COPYING in the source tree root for full license agreement.
  14  *
  15  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  16  * KIND, either express or implied.
  17  *
  18  ****************************************************************************/
  19 #include <stdbool.h>
  20 #include "config.h"
  21 #ifdef HAVE_MMC
  22 #include "ata_mmc.h"
  23 #else
  24 #include "hotswap.h"
  25 #endif
  26
  27 /* helper function to extract n (<=32) bits from an arbitrary position.
  28    counting from MSB to LSB */
  29 unsigned long card_extract_bits(
  30     const unsigned long *p, /* the start of the bitfield array */
  31     unsigned int start,     /* bit no. to start reading  */
  32     unsigned int size)      /* how many bits to read */
  33 {
  34     unsigned int long_index = start / 32;
  35     unsigned int bit_index = start % 32;
  36     unsigned long result;
  37
  38     result = p[long_index] << bit_index;
  39
  40     if (bit_index + size > 32)    /* crossing longword boundary */
  41         result |= p[long_index+1] >> (32 - bit_index);
  42
  43     result >>= 32 - size;
  44
  45     return result;
  46 }