gimbal_macro_utils.h

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/*! \file
 *  \brief Miscellaneous macro utilities and meta generators
 *  \ingroup preprocessor
 *  \sa gimbal_macro_composition.h, gimbal_macro_sequences.h
 *
 *  \author Falco Girgis
 *  \author 2025 Agustín Bellagamba
 */
 
#ifndef GIMBAL_MACRO_UTILS_H
#define GIMBAL_MACRO_UTILS_H
 
#include "gimbal_compiler.h"
#include "gimbal_macro_composition.h"
#include <gimbal/core/gimbal_config.h>
#include <stdint.h>
 
#ifdef __cplusplus
#include <functional>
extern "C" {
#endif
 
#define GBL_MIN(a, b)                       (((a) < (b))? (a) : (b))
#define GBL_MAX(a, b)                       (((a) > (b))? (a) : (b))
#define GBL_CEIL(numerator, denominator)    ((numerator / denominator + (numerator % denominator != 0)))
#define GBL_CLAMP(n, min, max)              (((n) > (max)) ? (max) : (((n) < (min)) ? (min) : (n)))
 
#define GBL_BIT_MASK_2(bits, offset)        (((1u << bits) - 1u) << offset)
#define GBL_BIT_MASK_1(bits)                GBL_BIT_MASK_2(bits, 0)
#define GBL_BIT_MASK(...)                   GBL_VA_OVERLOAD_CALL_ARGC(GBL_BIT_MASK, __VA_ARGS__)
 
#define GBL_BCD_BYTE_PACK(n)                (((n / 10) << 4) | (n % 10))            // 0-99
#define GBL_BCD_BYTE_UNPACK(n)              (unsigned)(((n >> 4) * 10) + (n & 0xf))
 
#define GBL_CONTAINER_OF(ptr, type, member) ((type*)((char*)(ptr) - offsetof(type, member)))
#define GBL_COUNT_OF(array)                 (sizeof(array) / sizeof(array[0]))
 
#define GBL_PTR_OFFSET(...)                 GBL_VA_OVERLOAD_CALL_ARGC(GBL_PTR_OFFSET, __VA_ARGS__)
#define GBL_PTR_OFFSET_3(type, ptr, bytes)  ((type)(((uintptr_t)ptr) + bytes))
#define GBL_PTR_OFFSET_2(ptr, bytes)        GBL_PTR_OFFSET_3(void*, ptr, bytes)
 
#define GBL_SWITCH_CASE_STRINGIFY(s)        case s: return #s
 
#define GBL_LABEL_EMPTY(name)               name: {;}
 
#define GBL_SWAP(x,y)
    GBL_STMT_START {
        unsigned char swap_temp[sizeof(x) == sizeof(y) ?
                               (signed)sizeof(x) : -1];
        memcpy(swap_temp, &y, sizeof(x));
        memcpy(&y, &x,        sizeof(x));
        memcpy(&x, swap_temp, sizeof(x));
    } GBL_STMT_END
 
#define GBL_ASSERT(...)
    GBL_VA_OVERLOAD_SELECT(GBL_ASSERT, GBL_VA_OVERLOAD_SUFFIXER_ARGC, __VA_ARGS__)(__VA_ARGS__)
 
//! Used to declare an endian-independent group of bitfields.
#define GBL_BIT_FIELDS(...)
    GBL_TUPLE_FOREACH(GBL_BIT_FIELDS_ENTRY_, GBL_PHONY, GBL_BIT_FIELDS_ENDIAN_XFORM_ (__VA_ARGS__))
 
#ifndef __cplusplus
#   define GBL_META_GENERIC_MACRO_GENERATE(traits, X)
    _Generic((X),
        GBL_MAP_TUPLES(GBL_META_GENERIC_MACRO_TRAIT_OVERLOADS_DECLARE_CASE_C_,
                       GBL_MAP_TUPLES(GBL_EVAL, GBL_META_GENERIC_MACRO_TRAIT_PROPERTY_OVERLOADS_ traits))
        default:  GBL_EVAL(GBL_META_GENERIC_MACRO_TRAIT_PROPERTY_DEFAULT traits)
    )
#else
#   define GBL_META_GENERIC_MACRO_GENERATE(traits, X)
     [](auto&&... args) {
        using GenericType = decltype(X);
        if constexpr(false);
        GBL_MAP_TUPLES(GBL_META_GENERIC_MACRO_TRAIT_OVERLOADS_DECLARE_CASE_CPP_,
                       GBL_MAP_TUPLES(GBL_EVAL, GBL_META_GENERIC_MACRO_TRAIT_PROPERTY_OVERLOADS_ traits))
        else if constexpr(requires { GBL_EVAL(GBL_META_GENERIC_MACRO_TRAIT_PROPERTY_DEFAULT_ traits)
                                             (std::forward<decltype(args)>(args)...); })
            return GBL_EVAL(GBL_META_GENERIC_MACRO_TRAIT_PROPERTY_DEFAULT_ traits)(std::forward<decltype(args)>(args)...);
    }
#endif
 
#define GBL_META_GENERIC_MACRO_TRAIT_PROPERTY_DEFAULT(defaultFunc, overloads)        defaultFunc
#define GBL_META_GENERIC_MACRO_NO_DEFAULT                                            GBL_NULL
 
// ===== Implementation ======
///\cond
#define GBL_BIT_FIELDS_ENTRY_(a, b) b;
 
#if GBL_BIG_ENDIAN
#   define GBL_BIT_FIELDS_ENDIAN_XFORM_(...) (__VA_ARGS__)
#else
#   define GBL_BIT_FIELDS_ENDIAN_XFORM_(...) (GBL_REVERSE(__VA_ARGS__))
#endif
 
#define GBL_META_GENERIC_MACRO_TRAIT_PROPERTY_OVERLOADS_(defaultFunc, overloads)     overloads
#define GBL_META_GENERIC_MACRO_TRAIT_OVERLOADS_PROPERTY_TYPE_(type, function)        type
#define GBL_META_GENERIC_MACRO_TRAIT_OVERLOADS_PROPERTY_FUNCTION_(type, function)    function
 
#define GBL_META_GENERIC_MACRO_TRAIT_OVERLOADS_DECLARE_CASE_C_(type, function)
    type: function,
 
#define GBL_META_GENERIC_MACRO_TRAIT_OVERLOADS_DECLARE_CASE_CPP_(type, function)
    else if constexpr(std::same_as<GenericType, type>) return function(std::forward<decltype(args)>(args)...);
///\endcond
#ifdef __cplusplus
}
#endif
 
#define GBL_SCOPE(begin, end) for (int GBL_APPEND_LINE(gblscope_) = ((begin), 0); GBL_APPEND_LINE(gblscope_) < 1; ++GBL_APPEND_LINE(gblscope_), (end))
#define GBL_SCOPE_EXIT continue
 
#define GBL_APPEND_LINE(a)  GBL_GLUE(GBL_GLUE(a, ), __LINE__)
 
#endif // GIMBAL_MACRO_UTILS_H