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/*
* Copyright © Michael Smith <mikesmiffy128@gmail.com>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
#ifndef INC_ACCESSOR_H
#define INC_ACCESSOR_H
#include "intdefs.h"
#include "mem.h"
#if defined(__GNUC__) || defined(__clang__)
#define _ACCESSOR_UNUSED __attribute__((unused))
#else
#define _ACCESSOR_UNUSED
#endif
/*
* Defines a function to offset a pointer from a struct/class to a member based
* on a corresponding offset value off_<field>. Such an offset would be
* generally defined in gamedata. The function will be named getptr_<field>.
* Essentially allows easy access to an opaque thing contained with another
* opaque thing.
*/
#define DEF_PTR_ACCESSOR(class, type, member) \
_ACCESSOR_UNUSED static inline typeof(type) *getptr_##member( \
typeof(class) *obj) { \
return mem_offset(obj, off_##member); \
}
/*
* Does the same as DEF_PTR_ACCESSOR, and also adds direct get/get functions.
* Requires that the field type is complete - that is, either scalar or a fully
* defined struct.
*/
#define DEF_ACCESSORS(class, type, member) \
DEF_PTR_ACCESSOR(class, type, member) \
_ACCESSOR_UNUSED static inline typeof(type) get_##member( \
const typeof(class) *obj) { \
return *getptr_##member((typeof(class) *)obj); \
} \
_ACCESSOR_UNUSED static inline void set_##member(typeof(class) *obj, \
typeof(type) val) { \
*getptr_##member(obj) = val; \
}
/*
* Defines an array indexing function arrayidx_<classname> which allows
* offsetting an opaque pointer by sz_<classname> bytes. This size value would
* generally be defined in gamedata. Allows iterating over structs/classes with
* sizes that vary by game and are thus unknown at compile time.
*
* Note that idx is signed so this can also be used for relative pointer offsets
* in either direction.
*
* Note on performance: obviously doing n * size requires a multiplication by a
* global, which poses a bit of an optimisation challenge in loops. Based on
* some testing though it seems like this *should* usually be optimised into a
* single load of the global followed by repeated addition with no need for
* multiplication, given that we use LTO, so... don't worry about it! It's fine!
*/
#define DEF_ARRAYIDX_ACCESSOR(type, classname) \
_ACCESSOR_UNUSED static inline typeof(type) *arrayidx_##classname( \
typeof(type) *array, ssize idx) { \
return mem_offset(array, idx * sz_##classname); \
}
#endif
// vi: sw=4 ts=4 noet tw=80 cc=80
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