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| -rw-r--r-- | include/linker_lists.h | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/include/linker_lists.h b/include/linker_lists.h new file mode 100644 index 0000000..0b405d7 --- /dev/null +++ b/include/linker_lists.h @@ -0,0 +1,148 @@ +/* + * include/linker_lists.h + * + * Implementation of linker-generated arrays + * + * Copyright (C) 2012 Marek Vasut <marex@denx.de> + * + * See file CREDITS for list of people who contributed to this + * project. + * + * 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. + */ +#ifndef __LINKER_LISTS_H__ +#define __LINKER_LISTS_H__ + +/** + * ll_entry_declare() - Declare linker-generated array entry + * @_type: Data type of the entry + * @_name: Name of the entry + * @_section_u: Subsection of u_boot_list in which this entry is placed + * (with underscores instead of dots, for name concatenation) + * @_section_d: Subsection of u_boot_list in which this entry is placed + * (with dots, for section concatenation) + * + * This macro declares a variable that is placed into a linker-generated + * array. This is a basic building block for more advanced use of linker- + * generated arrays. The user is expected to build their own macro wrapper + * around this one. + * + * A variable declared using this macro must be compile-time initialized + * and is as such placed into subsection of special section, .u_boot_list. + * The subsection is specified by the _section_[u,d] parameter, see below. + * The base name of the variable is _name, yet the actual variable is + * declared as concatenation of + * + * %_u_boot_list_ + @_section_u + _ + @_name + * + * which ensures name uniqueness. This variable shall never be refered + * directly though. + * + * Special precaution must be made when using this macro: + * 1) The _type must not contain the "static" keyword, otherwise the entry + * is not generated. + * + * 2) The @_section_u and @_section_d variables must match, the only difference + * is that in @_section_u is every dot "." character present in @_section_d + * replaced by a single underscore "_" character in @_section_u. The actual + * purpose of these parameters is to select proper subsection in the global + * .u_boot_list section. + * + * 3) In case a section is declared that contains some array elements AND a + * subsection of this section is declared and contains some elements, it is + * imperative that the elements are of the same type. + * + * 4) In case an outer section is declared that contains some array elements + * AND am inner subsection of this section is declared and contains some + * elements, then when traversing the outer section, even the elements of + * the inner sections are present in the array. + * + * Example: + * ll_entry_declare(struct my_sub_cmd, my_sub_cmd, cmd_sub, cmd.sub) = { + * .x = 3, + * .y = 4, + * }; + */ +#define ll_entry_declare(_type, _name, _section_u, _section_d) \ + _type _u_boot_list_##_section_u##_##_name __attribute__(( \ + unused, aligned(4), \ + section(".u_boot_list."#_section_d"."#_name))) + +/** + * ll_entry_start() - Point to first entry of linker-generated array + * @_type: Data type of the entry + * @_section_u: Subsection of u_boot_list in which this entry is placed + * (with underscores instead of dots) + * + * This function returns (_type *) pointer to the very first entry of a + * linker-generated array placed into subsection of .u_boot_list section + * specified by _section_u argument. + * + * Example: + * struct my_sub_cmd *msc = ll_entry_start(struct my_sub_cmd, cmd_sub); + */ +#define ll_entry_start(_type, _section_u) \ + ({ \ + extern _type _u_boot_list_##_section_u##__start; \ + _type *_ll_result = &_u_boot_list_##_section_u##__start;\ + _ll_result; \ + }) + +/** + * ll_entry_count() - Return the number of elements in linker-generated array + * @_type: Data type of the entry + * @_section_u: Subsection of u_boot_list in which this entry is placed + * (with underscores instead of dots) + * + * This function returns the number of elements of a linker-generated array + * placed into subsection of .u_boot_list section specified by _section_u + * argument. The result is of an unsigned int type. + * + * Example: + * int i; + * const unsigned int count = ll_entry_count(struct my_sub_cmd, cmd_sub); + * struct my_sub_cmd *msc = ll_entry_start(struct my_sub_cmd, cmd_sub); + * for (i = 0; i < count; i++, msc++) + * printf("Entry %i, x=%i y=%i\n", i, msc->x, msc->y); + */ +#define ll_entry_count(_type, _section_u) \ + ({ \ + extern _type _u_boot_list_##_section_u##__start; \ + extern _type _u_boot_list_##_section_u##__end; \ + unsigned int _ll_result = \ + &_u_boot_list_##_section_u##__end - \ + &_u_boot_list_##_section_u##__start; \ + _ll_result; \ + }) + + +/** + * ll_entry_get() - Retrieve entry from linker-generated array by name + * @_type: Data type of the entry + * @_name: Name of the entry + * @_section_u: Subsection of u_boot_list in which this entry is placed + * (with underscores instead of dots) + * + * This function returns a pointer to a particular entry in LG-array + * identified by the subsection of u_boot_list where the entry resides + * and it's name. + * + * Example: + * ll_entry_declare(struct my_sub_cmd, my_sub_cmd, cmd_sub, cmd.sub) = { + * .x = 3, + * .y = 4, + * }; + * ... + * struct my_sub_cmd *c = ll_entry_get(struct my_sub_cmd, my_sub_cmd, cmd_sub); + */ +#define ll_entry_get(_type, _name, _section_u) \ + ({ \ + extern _type _u_boot_list_##_section_u##_##_name; \ + _type *_ll_result = &_u_boot_list_##_section_u##_##_name;\ + _ll_result; \ + }) + +#endif /* __LINKER_LISTS_H__ */ |