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 #ifndef BINARYBUFFER_H
  24 #define BINARYBUFFER_H
  25
  26 #include <helper/types.h>
  27
  28 /** @file
  29  * Support functions to access arbitrary bits in a byte array
  30  */
  31
  32 /**
  33  * Sets @c num bits in @c _buffer, starting at the @c first bit,
  34  * using the bits in @c value.  This routine fast-paths writes
  35  * of little-endian, byte-aligned, 32-bit words.
  36  * @param _buffer The buffer whose bits will be set.
  37  * @param first The bit offset in @c _buffer to start writing (0-31).
  38  * @param num The number of bits from @c value to copy (1-32).
  39  * @param value Up to 32 bits that will be copied to _buffer.
  40  */
  41 static inline void buf_set_u32(void *_buffer,
  42                 unsigned first, unsigned num, uint32_t value)
  43 {
  44         uint8_t *buffer = (uint8_t *)_buffer;
  45
  46         if ((num == 32) && (first == 0)) {
  47                 buffer[3] = (value >> 24) & 0xff;
  48                 buffer[2] = (value >> 16) & 0xff;
  49                 buffer[1] = (value >> 8) & 0xff;
  50                 buffer[0] = (value >> 0) & 0xff;
  51         } else {
  52                 for (unsigned i = first; i < first + num; i++)
  53                 {
  54                         if (((value >> (i - first)) & 1) == 1)
  55                                 buffer[i / 8] |= 1 << (i % 8);
  56                         else
  57                                 buffer[i / 8] &= ~(1 << (i % 8));
  58                 }
  59         }
  60 }
  61 /**
  62  * Retrieves @c num bits from @c _buffer, starting at the @c first bit,
  63  * returning the bits in a 32-bit word.  This routine fast-paths reads
  64  * of little-endian, byte-aligned, 32-bit words.
  65  * @param _buffer The buffer whose bits will be read.
  66  * @param first The bit offset in @c _buffer to start reading (0-31).
  67  * @param num The number of bits from @c _buffer to read (1-32).
  68  * @returns Up to 32-bits that were read from @c _buffer.
  69  */
  70 static inline uint32_t buf_get_u32(const void *_buffer,
  71                 unsigned first, unsigned num)
  72 {
  73         uint8_t *buffer = (uint8_t *)_buffer;
  74
  75         if ((num == 32) && (first == 0)) {
  76                 return (((uint32_t)buffer[3]) << 24) |
  77                         (((uint32_t)buffer[2]) << 16) |
  78                         (((uint32_t)buffer[1]) << 8) |
  79                         (((uint32_t)buffer[0]) << 0);
  80         } else {
  81                 uint32_t result = 0;
  82                 for (unsigned i = first; i < first + num; i++)
  83                 {
  84                         if (((buffer[i / 8] >> (i % 8)) & 1) == 1)
  85                                 result |= 1 << (i - first);
  86                 }
  87                 return result;
  88         }
  89 }
  90
  91 /**
  92  * Inverts the ordering of bits inside a 32-bit word (e.g. 31..0 -> 0..31).
  93  * This routine can be used to flip smaller data types by using smaller
  94  * values for @c width.
  95  * @param value The word to flip.
  96  * @param width The number of bits in value (2-32).
  97  * @returns A 32-bit word with @c value in reversed bit-order.
  98  */
  99 uint32_t flip_u32(uint32_t value, unsigned width);
 100
 101 bool buf_cmp(const void *buf1, const void *buf2, unsigned size);
 102 bool buf_cmp_mask(const void *buf1, const void *buf2,
 103                 const void *mask, unsigned size);
 104
 105 /**
 106  * Copies @c size bits out of @c from and into @c to.  Any extra
 107  * bits in the final byte will be set to zero.
 108  * @param from The buffer to copy into @c to.
 109  * @param to The buffer that will receive the copy of @c from.
 110  * @param size The number of bits to copy.
 111  */
 112 void* buf_cpy(const void *from, void *to, unsigned size);
 113
 114 /**
 115  * Set the contents of @c buf with @c count bits, all set to 1.
 116  * @param buf The buffer to fill with ones.
 117  * @param size The number of bits.
 118  * @returns The original buffer (@c buf).
 119  */
 120 void* buf_set_ones(void *buf, unsigned size);
 121
 122 void* buf_set_buf(const void *src, unsigned src_start,
 123                 void *dst, unsigned dst_start, unsigned len);
 124
 125 int str_to_buf(const char *str, unsigned len,
 126                 void *bin_buf, unsigned buf_size, unsigned radix);
 127 char* buf_to_str(const void *buf, unsigned size, unsigned radix);
 128
 129 /* read a uint32_t from a buffer in target memory endianness */
 130 static inline uint32_t fast_target_buffer_get_u32(const void *p, bool le)
 131 {
 132         return le ? le_to_h_u32(p) : be_to_h_u32(p);
 133 }
 134
 135 #endif /* BINARYBUFFER_H */