src/helper/binarybuffer.h

   1 /***************************************************************************
   2  *   Copyright (C) 2004, 2005 by Dominic Rath                              *
   3  *   Dominic.Rath@gmx.de                                                   *
   4  *                                                                         *
   5  *   Copyright (C) 2007,2008 Øyvind Harboe                                 *
   6  *   oyvind.harboe@zylin.com                                               *
   7  *                                                                         *
   8  *   This program is free software; you can redistribute it and/or modify  *
   9  *   it under the terms of the GNU General Public License as published by  *
  10  *   the Free Software Foundation; either version 2 of the License, or     *
  11  *   (at your option) any later version.                                   *
  12  *                                                                         *
  13  *   This program 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 this program; if not, write to the                         *
  20  *   Free Software Foundation, Inc.,                                       *
  21  *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
  22  ***************************************************************************/
  23
  24 #ifndef BINARYBUFFER_H
  25 #define BINARYBUFFER_H
  26
  27 /** @file
  28  * Support functions to access arbitrary bits in a byte array
  29  */
  30
  31 /**
  32  * Sets @c num bits in @c _buffer, starting at the @c first bit,
  33  * using the bits in @c value.  This routine fast-paths writes
  34  * of little-endian, byte-aligned, 32-bit words.
  35  * @param _buffer The buffer whose bits will be set.
  36  * @param first The bit offset in @c _buffer to start writing (0-31).
  37  * @param num The number of bits from @c value to copy (1-32).
  38  * @param value Up to 32 bits that will be copied to _buffer.
  39  */
  40 static inline void buf_set_u32(void *_buffer,
  41         unsigned first, unsigned num, uint32_t value)
  42 {
  43         uint8_t *buffer = (uint8_t *)_buffer;
  44
  45         if ((num == 32) && (first == 0)) {
  46                 buffer[3] = (value >> 24) & 0xff;
  47                 buffer[2] = (value >> 16) & 0xff;
  48                 buffer[1] = (value >> 8) & 0xff;
  49                 buffer[0] = (value >> 0) & 0xff;
  50         } else {
  51                 for (unsigned i = first; i < first + num; i++) {
  52                         if (((value >> (i - first)) & 1) == 1)
  53                                 buffer[i / 8] |= 1 << (i % 8);
  54                         else
  55                                 buffer[i / 8] &= ~(1 << (i % 8));
  56                 }
  57         }
  58 }
  59 /**
  60  * Retrieves @c num bits from @c _buffer, starting at the @c first bit,
  61  * returning the bits in a 32-bit word.  This routine fast-paths reads
  62  * of little-endian, byte-aligned, 32-bit words.
  63  * @param _buffer The buffer whose bits will be read.
  64  * @param first The bit offset in @c _buffer to start reading (0-31).
  65  * @param num The number of bits from @c _buffer to read (1-32).
  66  * @returns Up to 32-bits that were read from @c _buffer.
  67  */
  68 static inline uint32_t buf_get_u32(const void *_buffer,
  69         unsigned first, unsigned num)
  70 {
  71         uint8_t *buffer = (uint8_t *)_buffer;
  72
  73         if ((num == 32) && (first == 0)) {
  74                 return (((uint32_t)buffer[3]) << 24) |
  75                                 (((uint32_t)buffer[2]) << 16) |
  76                                 (((uint32_t)buffer[1]) << 8) |
  77                                 (((uint32_t)buffer[0]) << 0);
  78         } else {
  79                 uint32_t result = 0;
  80                 for (unsigned i = first; i < first + num; i++) {
  81                         if (((buffer[i / 8] >> (i % 8)) & 1) == 1)
  82                                 result |= 1 << (i - first);
  83                 }
  84                 return result;
  85         }
  86 }
  87
  88 /**
  89  * Inverts the ordering of bits inside a 32-bit word (e.g. 31..0 -> 0..31).
  90  * This routine can be used to flip smaller data types by using smaller
  91  * values for @c width.
  92  * @param value The word to flip.
  93  * @param width The number of bits in value (2-32).
  94  * @returns A 32-bit word with @c value in reversed bit-order.
  95  */
  96 uint32_t flip_u32(uint32_t value, unsigned width);
  97
  98 bool buf_cmp(const void *buf1, const void *buf2, unsigned size);
  99 bool buf_cmp_mask(const void *buf1, const void *buf2,
 100                 const void *mask, unsigned size);
 101
 102 /**
 103  * Copies @c size bits out of @c from and into @c to.  Any extra
 104  * bits in the final byte will be set to zero.
 105  * @param from The buffer to copy into @c to.
 106  * @param to The buffer that will receive the copy of @c from.
 107  * @param size The number of bits to copy.
 108  */
 109 void *buf_cpy(const void *from, void *to, unsigned size);
 110
 111 /**
 112  * Set the contents of @c buf with @c count bits, all set to 1.
 113  * @param buf The buffer to fill with ones.
 114  * @param size The number of bits.
 115  * @returns The original buffer (@c buf).
 116  */
 117 void *buf_set_ones(void *buf, unsigned size);
 118
 119 void *buf_set_buf(const void *src, unsigned src_start,
 120                   void *dst, unsigned dst_start, unsigned len);
 121
 122 int str_to_buf(const char *str, unsigned len,
 123                 void *bin_buf, unsigned buf_size, unsigned radix);
 124 char *buf_to_str(const void *buf, unsigned size, unsigned radix);
 125
 126 /* read a uint32_t from a buffer in target memory endianness */
 127 static inline uint32_t fast_target_buffer_get_u32(const void *p, bool le)
 128 {
 129         return le ? le_to_h_u32(p) : be_to_h_u32(p);
 130 }
 131
 132 #endif  /* BINARYBUFFER_H */