types/bitfield.c

   1 /*
   2  * BabelTrace - Bitfield Type Converter
   3  *
   4  * Copyright (c) 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 #include <babeltrace/compiler.h>
  22 #include <babeltrace/types.h>
  23 #include <stdint.h>
  24
  25 /*
  26  * Shortcut to integer copy if we copy bit-aligned data with 0 start_offset.
  27  * This skips the bitfield overhead when dealing with enumerations (which use
  28  * the bitfield copy functions).
  29  */
  30 extern
  31 size_t integer_copy(unsigned char *dest, const struct format *fdest,
  32                     const unsigned char *src, const struct format *fsrc,
  33                     const struct type_class *type_class);
  34
  35 size_t bitfield_copy(unsigned char *dest, const struct format *fdest,
  36                      const unsigned char *src, const struct format *fsrc,
  37                      const struct type_class *type_class)
  38 {
  39         struct type_class_bitfield *bitfield_class =
  40                 container_of(type_class, struct type_class_bitfield, p);
  41         struct type_class_integer *int_class = &bitfield_class->p;
  42
  43         if (!(int_class->p.alignment % CHAR_BIT)
  44             && !(int_class->len % CHAR_BIT)
  45             && !(bitfield_class->start_offset % CHAR_BIT)) {
  46                 size_t offset = bitfield_class->start_offset / CHAR_BIT;
  47                 dest += offset;
  48                 src += offset;
  49                 return integer_copy(dest, fdest, src, fsrc, type_class);
  50         }
  51
  52         if (!int_class->signedness) {
  53                 uint64_t v;
  54
  55                 v = fsrc->bitfield_unsigned_read(src,
  56                                         bitfield_class->start_offset,
  57                                         int_class->len,
  58                                         int_class->byte_order);
  59                 return fdest->bitfield_unsigned_write(dest,
  60                                         bitfield_class->start_offset,
  61                                         int_class->len, int_class->byte_order,
  62                                         v);
  63         } else {
  64                 int64_t v;
  65
  66                 v = fsrc->bitfield_signed_read(src,
  67                                         bitfield_class->start_offset,
  68                                         int_class->len,
  69                                         int_class->byte_order);
  70                 return fdest->bitfield_signed_write(dest,
  71                                         bitfield_class->start_offset,
  72                                         int_class->len, int_class->byte_order,
  73                                         v);
  74         }
  75 }
  76
  77 void bitfield_type_free(struct type_class_bitfield *bitfield_class)
  78 {
  79         g_free(bitfield_class);
  80 }
  81
  82 static void _bitfield_type_free(struct type_class *type_class)
  83 {
  84         struct type_class_bitfield *bitfield_class =
  85                 container_of(type_class, struct type_class_bitfield, p);
  86         bitfield_type_free(bitfield_class);
  87 }
  88
  89 struct type_class_bitfield *bitfield_type_new(const char *name,
  90                                               size_t start_offset,
  91                                               size_t len, int byte_order,
  92                                               int signedness,
  93                                               size_t alignment)
  94 {
  95         struct type_class_bitfield *bitfield_class;
  96         struct type_class_integer *int_class;
  97         int ret;
  98
  99         bitfield_class = g_new(struct type_class_bitfield, 1);
 100         int_class = &bitfield_class->p;
 101         int_class->p.name = g_quark_from_string(name);
 102         int_class->p.alignment = alignment;
 103         int_class->p.copy = bitfield_copy;
 104         int_class->p.free = _bitfield_type_free;
 105         int_class->len = len;
 106         int_class->byte_order = byte_order;
 107         int_class->signedness = signedness;
 108         bitfield_class->start_offset = start_offset;
 109         if (int_class->p.name) {
 110                 ret = ctf_register_type(&int_class->p);
 111                 if (ret) {
 112                         g_free(bitfield_class);
 113                         return NULL;
 114                 }
 115         }
 116         return bitfield_class;
 117 }