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Diffstat (limited to 'include/stddef.h')
-rw-r--r-- | include/stddef.h | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/include/stddef.h b/include/stddef.h new file mode 100644 index 0000000..b8ad4ea --- /dev/null +++ b/include/stddef.h @@ -0,0 +1,72 @@ +/** + * slibc — Yet another C library + * Copyright © 2015 Mattias Andrée (maandree@member.fsf.org) + * + * 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 3 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, see <http://www.gnu.org/licenses/>. + */ +#ifndef _STDDEF_H +#define _STDDEF_H + + + +/** + * `NULL` is a zero-values constant, conventionally + * a `void`-pointer (it is specified this way in + * POSIX, it does not really matter and ISO C does + * not specify it this way), use to indicate that + * a pointer does not point to anything. + */ +#define NULL ((void*)0) + + +/** + * Get the offset of a member in a `struct`, in bytes. + * + * For example. Consider the structure + * ``` + * struct example + * { + * char offset_is_0[16]; + * char offset_is_16[16]; + * } + * ``` + * `offsetof(struct example, offset_is_0)` evaluates to + * 0 because it is at the top of the structure. + * `offsetof(struct example, offset_is_16)` evaluates to + * 16 because the member above it in the structure + * has offset 0 and size 16. 0 + 16 = 16. + * + * @param type:identifier The identifier for a structure. + * @param member:identifier The identifier for a member, direct or indirect, + * of the structure. + * @return :size_t The offset of the member. + */ +#define offsetof(type, member) \ + ((size_t)((char*)&(((type*)NULL)->member) - (char*)NULL)) + + + +#define __NEED_ptrdiff_t +#define __NEED_wchar_t +#define __NEED_size_t +#if __STDC_VERSION__ >= 201112L +# define __NEED_max_align_t +#endif + +#include <bits/types.h> + + + +#endif + |