Import tables.h from gpxe

Imported tables.h from the gpxe project [0] as of
commit c23508d796325f8af724ad497c99ffb5a49abea0.
This code is licensed under the GPLv2.

[0] git://git.etherboot.org/scm/gpxe.git

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>

2 files changed, 773 insertions, 0 deletions

diff --git a/COPYING b/COPYING
new file mode 100644
index 0000000..a43ea21
--- /dev/null
+++ b/COPYING
@@ -0,0 +1,339 @@
+		    GNU GENERAL PUBLIC LICENSE
+		       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.
+                          675 Mass Ave, Cambridge, MA 02139, USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+			    Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
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+Foundation's software and to any other program whose authors commit to
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+  When we speak of free software, we are referring to freedom, not
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+
+		    GNU GENERAL PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. This License applies to any program or other work which contains
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+  1. You may copy and distribute verbatim copies of the Program's
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+
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+
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+
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+		     END OF TERMS AND CONDITIONS
+
+	Appendix: How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) 19yy  <name of author>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+    Gnomovision version 69, Copyright (C) 19yy name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Library General
+Public License instead of this License.
diff --git a/tables.h b/tables.h
new file mode 100644
index 0000000..7dfced8
--- /dev/null
+++ b/tables.h
@@ -0,0 +1,434 @@
+#ifndef _GPXE_TABLES_H
+#define _GPXE_TABLES_H
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/** @page ifdef_harmful #ifdef considered harmful
+ *
+ * Overuse of @c #ifdef has long been a problem in Etherboot.
+ * Etherboot provides a rich array of features, but all these features
+ * take up valuable space in a ROM image.  The traditional solution to
+ * this problem has been for each feature to have its own @c #ifdef
+ * option, allowing the feature to be compiled in only if desired.
+ *
+ * The problem with this is that it becomes impossible to compile, let
+ * alone test, all possible versions of Etherboot.  Code that is not
+ * typically used tends to suffer from bit-rot over time.  It becomes
+ * extremely difficult to predict which combinations of compile-time
+ * options will result in code that can even compile and link
+ * correctly.
+ *
+ * To solve this problem, we have adopted a new approach from
+ * Etherboot 5.5 onwards.  @c #ifdef is now "considered harmful", and
+ * its use should be minimised.  Separate features should be
+ * implemented in separate @c .c files, and should \b always be
+ * compiled (i.e. they should \b not be guarded with a @c #ifdef @c
+ * MY_PET_FEATURE statement).  By making (almost) all code always
+ * compile, we avoid the problem of bit-rot in rarely-used code.
+ *
+ * The file config.h, in combination with the @c make command line,
+ * specifies the objects that will be included in any particular build
+ * of Etherboot.  For example, suppose that config.h includes the line
+ *
+ * @code
+ *
+ *   #define CONSOLE_SERIAL
+ *   #define DOWNLOAD_PROTO_TFTP
+ *
+ * @endcode
+ *
+ * When a particular Etherboot image (e.g. @c bin/rtl8139.zdsk) is
+ * built, the options specified in config.h are used to drag in the
+ * relevant objects at link-time.  For the above example, serial.o and
+ * tftp.o would be linked in.
+ *
+ * There remains one problem to solve: how do these objects get used?
+ * Traditionally, we had code such as
+ *
+ * @code
+ *
+ *    #ifdef CONSOLE_SERIAL
+ *      serial_init();
+ *    #endif
+ *
+ * @endcode
+ *
+ * in main.c, but this reintroduces @c #ifdef and so is a Bad Idea.
+ * We cannot simply remove the @c #ifdef and make it
+ *
+ * @code
+ *
+ *   serial_init();
+ *
+ * @endcode
+ *
+ * because then serial.o would end up always being linked in.
+ *
+ * The solution is to use @link tables.h linker tables @endlink.
+ *
+ */
+
+/** @file
+ *
+ * Linker tables
+ *
+ * Read @ref ifdef_harmful first for some background on the motivation
+ * for using linker tables.
+ *
+ * This file provides macros for dealing with linker-generated tables
+ * of fixed-size symbols.  We make fairly extensive use of these in
+ * order to avoid @c #ifdef spaghetti and/or linker symbol pollution.
+ * For example, instead of having code such as
+ *
+ * @code
+ *
+ *    #ifdef CONSOLE_SERIAL
+ *      serial_init();
+ *    #endif
+ *
+ * @endcode
+ *
+ * we make serial.c generate an entry in the initialisation function
+ * table, and then have a function call_init_fns() that simply calls
+ * all functions present in this table.  If and only if serial.o gets
+ * linked in, then its initialisation function will be called.  We
+ * avoid linker symbol pollution (i.e. always dragging in serial.o
+ * just because of a call to serial_init()) and we also avoid @c
+ * #ifdef spaghetti (having to conditionalise every reference to
+ * functions in serial.c).
+ *
+ * The linker script takes care of assembling the tables for us.  All
+ * our table sections have names of the format @c .tbl.NAME.NN where
+ * @c NAME designates the data structure stored in the table (e.g. @c
+ * init_fns) and @c NN is a two-digit decimal number used to impose an
+ * ordering upon the tables if required.  @c NN=00 is reserved for the
+ * symbol indicating "table start", and @c NN=99 is reserved for the
+ * symbol indicating "table end".
+ *
+ * As an example, suppose that we want to create a "frobnicator"
+ * feature framework, and allow for several independent modules to
+ * provide frobnicating services.  Then we would create a frob.h
+ * header file containing e.g.
+ *
+ * @code
+ *
+ *   struct frobnicator {
+ *      const char *name;		// Name of the frobnicator
+ *	void ( *frob ) ( void ); 	// The frobnicating function itself
+ *   };
+ *
+ *   #define FROBNICATORS __table ( struct frobnicator, "frobnicators" )
+ *
+ *   #define __frobnicator __table_entry ( FROBNICATORS, 01 )
+ *
+ * @endcode
+ *
+ * Any module providing frobnicating services would look something
+ * like
+ *
+ * @code
+ *
+ *   #include "frob.h"
+ *
+ *   static void my_frob ( void ) {
+ *	// Do my frobnicating
+ *	...
+ *   }
+ *
+ *   struct frob my_frobnicator __frobnicator = {
+ *	.name = "my_frob",
+ *	.frob = my_frob,
+ *   };
+ *
+ * @endcode
+ *
+ * The central frobnicator code (frob.c) would use the frobnicating
+ * modules as follows
+ *
+ * @code
+ *
+ *   #include "frob.h"
+ *
+ *   // Call all linked-in frobnicators
+ *   void frob_all ( void ) {
+ *	struct frob *frob;
+ *
+ *	for_each_table ( frob, FROBNICATORS ) {
+ *         printf ( "Calling frobnicator \"%s\"\n", frob->name );
+ *	   frob->frob ();
+ *	}
+ *   }
+ *
+ * @endcode
+ *
+ * See init.h and init.c for a real-life example.
+ *
+ */
+
+#ifdef DOXYGEN
+#define __attribute__( x )
+#endif
+
+/**
+ * Declare a linker table
+ *
+ * @v type		Data type
+ * @v name		Table name
+ * @ret table		Linker table
+ */
+#define __table( type, name ) ( type, name )
+
+/**
+ * Get linker table data type
+ *
+ * @v table		Linker table
+ * @ret type		Data type
+ */
+#define __table_type( table ) __table_extract_type table
+#define __table_extract_type( type, name ) type
+
+/**
+ * Get linker table name
+ *
+ * @v table		Linker table
+ * @ret name		Table name
+ */
+#define __table_name( table ) __table_extract_name table
+#define __table_extract_name( type, name ) name
+
+/**
+ * Get linker table section name
+ *
+ * @v table		Linker table
+ * @v idx		Sub-table index
+ * @ret section		Section name
+ */
+#define __table_section( table, idx ) \
+	".tbl." __table_name ( table ) "." __table_str ( idx )
+#define __table_str( x ) #x
+
+/**
+ * Get linker table alignment
+ *
+ * @v table		Linker table
+ * @ret align		Alignment
+ */
+#define __table_alignment( table ) __alignof__ ( __table_type ( table ) )
+
+/**
+ * Declare a linker table entry
+ *
+ * @v table		Linker table
+ * @v idx		Sub-table index
+ *
+ * Example usage:
+ *
+ * @code
+ *
+ *   #define FROBNICATORS __table ( struct frobnicator, "frobnicators" )
+ *
+ *   #define __frobnicator __table_entry ( FROBNICATORS, 01 )
+ *
+ *   struct frobnicator my_frob __frobnicator = {
+ *      ...
+ *   };
+ *
+ * @endcode
+ */
+#define __table_entry( table, idx )					\
+	__attribute__ (( __section__ ( __table_section ( table, idx ) ),\
+			 __aligned__ ( __table_alignment ( table ) ) ))
+
+/**
+ * Get start of linker table entries
+ *
+ * @v table		Linker table
+ * @v idx		Sub-table index
+ * @ret entries		Start of entries
+ */
+#define __table_entries( table, idx ) ( {				\
+	static __table_type ( table ) __table_entries[0]		\
+		__table_entry ( table, idx ); 				\
+	__table_entries; } )
+
+/**
+ * Get start of linker table
+ *
+ * @v table		Linker table
+ * @ret start		Start of linker table
+ *
+ * Example usage:
+ *
+ * @code
+ *
+ *   #define FROBNICATORS __table ( struct frobnicator, "frobnicators" )
+ *
+ *   struct frobnicator *frobs = table_start ( FROBNICATORS );
+ *
+ * @endcode
+ */
+#define table_start( table ) __table_entries ( table, 00 )
+
+/**
+ * Get end of linker table
+ *
+ * @v table		Linker table
+ * @ret end		End of linker table
+ *
+ * Example usage:
+ *
+ * @code
+ *
+ *   #define FROBNICATORS __table ( struct frobnicator, "frobnicators" )
+ *
+ *   struct frobnicator *frobs_end = table_end ( FROBNICATORS );
+ *
+ * @endcode
+ */
+#define table_end( table ) __table_entries ( table, 99 )
+
+/**
+ * Get number of entries in linker table
+ *
+ * @v table		Linker table
+ * @ret num_entries	Number of entries in linker table
+ *
+ * Example usage:
+ *
+ * @code
+ *
+ *   #define FROBNICATORS __table ( struct frobnicator, "frobnicators" )
+ *
+ *   unsigned int num_frobs = table_num_entries ( FROBNICATORS );
+ *
+ * @endcode
+ *
+ */
+#define table_num_entries( table )					\
+	( ( unsigned int ) ( table_end ( table ) -			\
+			     table_start ( table ) ) )
+
+/**
+ * Iterate through all entries within a linker table
+ *
+ * @v pointer		Entry pointer
+ * @v table		Linker table
+ *
+ * Example usage:
+ *
+ * @code
+ *
+ *   #define FROBNICATORS __table ( struct frobnicator, "frobnicators" )
+ *
+ *   struct frobnicator *frob;
+ *
+ *   for_each_table_entry ( frob, FROBNICATORS ) {
+ *     ...
+ *   }
+ *
+ * @endcode
+ *
+ */
+#define for_each_table_entry( pointer, table )				\
+	for ( pointer = table_start ( table ) ;				\
+	      pointer < table_end ( table ) ;				\
+	      pointer++ )
+
+/**
+ * Iterate through all entries within a linker table in reverse order
+ *
+ * @v pointer		Entry pointer
+ * @v table		Linker table
+ *
+ * Example usage:
+ *
+ * @code
+ *
+ *   #define FROBNICATORS __table ( struct frobnicator, "frobnicators" )
+ *
+ *   struct frobnicator *frob;
+ *
+ *   for_each_table_entry_reverse ( frob, FROBNICATORS ) {
+ *     ...
+ *   }
+ *
+ * @endcode
+ *
+ */
+#define for_each_table_entry_reverse( pointer, table )			\
+	for ( pointer = ( table_end ( table ) - 1 ) ;			\
+	      pointer >= table_start ( table ) ;			\
+	      pointer-- )
+
+/******************************************************************************
+ *
+ * Intel's C compiler chokes on several of the constructs used in this
+ * file.  The workarounds are ugly, so we use them only for an icc
+ * build.
+ *
+ */
+#define ICC_ALIGN_HACK_FACTOR 128
+#ifdef __ICC
+
+/*
+ * icc miscompiles zero-length arrays by inserting padding to a length
+ * of two array elements.  We therefore have to generate the
+ * __table_entries() symbols by hand in asm.
+ *
+ */
+#undef __table_entries
+#define __table_entries( table, idx ) ( {				\
+	extern __table_type ( table )					\
+		__table_temp_sym ( idx, __LINE__ ) []			\
+		__table_entry ( table, idx ) 				\
+		asm ( __table_entries_sym ( table, idx ) );		\
+	__asm__ ( ".ifndef %c0\n\t"					\
+		  ".section " __table_section ( table, idx ) "\n\t"	\
+		  ".align %c1\n\t"					\
+	          "\n%c0:\n\t"						\
+		  ".previous\n\t" 					\
+		  ".endif\n\t"						\
+		  : : "i" ( __table_temp_sym ( idx, __LINE__ ) ),	\
+		      "i" ( __table_alignment ( table ) ) );		\
+	__table_temp_sym ( idx, __LINE__ ); } )
+#define __table_entries_sym( table, idx )				\
+	"__tbl_" __table_name ( table ) "_" #idx
+#define __table_temp_sym( a, b )					\
+	___table_temp_sym( __table_, a, _, b )
+#define ___table_temp_sym( a, b, c, d ) a ## b ## c ## d
+
+/*
+ * icc ignores __attribute__ (( aligned (x) )) when it is used to
+ * decrease the compiler's default choice of alignment (which may be
+ * higher than the alignment actually required by the structure).  We
+ * work around this by forcing the alignment to a large multiple of
+ * the required value (so that we are never attempting to decrease the
+ * default alignment) and then postprocessing the object file to
+ * reduce the alignment back down to the "real" value.
+ *
+ */
+#undef __table_alignment
+#define __table_alignment( table ) \
+	( ICC_ALIGN_HACK_FACTOR * __alignof__ ( __table_type ( table ) ) )
+
+/*
+ * Because of the alignment hack, we must ensure that the compiler
+ * never tries to place multiple objects within the same section,
+ * otherwise the assembler will insert padding to the (incorrect)
+ * alignment boundary.  Do this by appending the line number to table
+ * section names.
+ *
+ * Note that we don't need to worry about padding between array
+ * elements, since the alignment is declared on the variable (i.e. the
+ * whole array) rather than on the type (i.e. on all individual array
+ * elements).
+ */
+#undef __table_section
+#define __table_section( table, idx ) \
+	".tbl." __table_name ( table ) "." __table_str ( idx ) \
+	"." __table_xstr ( __LINE__ )
+#define __table_xstr( x ) __table_str ( x )
+
+#endif /* __ICC */
+
+#endif /* _GPXE_TABLES_H */