Joshua Wise's Git repositories - netwatch.git/blob

1 /* tables.h

2 * Linker table helper macros.

3 * NetWatch system management mode administration console

4 *

7 *

8 * Redistribution and use in source and binary forms, with or without

9 * modification, are permitted provided that the following conditions are

10 * met:

11 *

12 * * Redistributions of source code must retain the above copyright

13 * notice, this list of conditions and the following disclaimer.

14 * * Redistributions in binary form must reproduce the above

15 * copyright notice, this list of conditions and the following disclaimer

16 * in the documentation and/or other materials provided with the

17 * distribution.

18 * * Neither the name of Google Inc. nor the names of its

19 * contributors may be used to endorse or promote products derived from

20 * this software without specific prior written permission.

21 *

22 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

23 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

24 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

25 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

26 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

27 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

28 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

32 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

33 */

34

35 #ifndef __TABLES_H

36 #define __TABLES_H

37

38 /* Linker tables are a beautiful, evil piece of magic.

39 *

40 * The idea is this;

41 * - For each table, define start and end pointers as zero-length arrays.

42 * - Define however many data values as constants of the appropriate type

43 * - Put each in its own section. For example, 'start' is in section

44 * .table.foo; the data elemnts are in section .table.foo.1 (or other values

45 * for explicit ordering); and 'end' is in .table.foo.END.

46 * - Merge the sections together with the following linker script entry:

47 * *(SORT(.table.*))

48 *

49 * This has the effect that the start symbol points to the first value in the

50 * table, and the end symbol points to the last. The number of values is

51 * simply (table_foo_end - table_foo_start).

52 *

53 * And everything Just Works. Etherboot and the Linux kernel both use this

54 * for identifying linked-in modules; they have a somewhat more elaborate

55 * macro infastructure, but at the moment there are only two tables in

56 * NetWatch (network protocols and built-in drivers), so less is needed.

57 */

58

59 #define PROTOCOL(x) void (* const x##_ptr)(void) \

60 __attribute__((section(".table.protocols.1"))) = x

61

62

63

64 #define TABLE(typ, name) \

65 typ name##_table[0] __attribute__((section(".table." #name ))); \

66 typ name##_table_end[0] __attribute__((section(".table." #name ".END")));

67

68 #define TABLE_LENGTH(name) (name##_table_end - name##_table)

69

70 #endif /* __TABLES_H */

71