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#ifndef RBIMPL_ARITHMERIC_ST_DATA_T_H /*-*-C++-*-vi:se ft=cpp:*/
#define RBIMPL_ARITHMERIC_ST_DATA_T_H
/**
* @file
* @author Ruby developers <ruby-core@ruby-lang.org>
* @copyright This file is a part of the programming language Ruby.
* Permission is hereby granted, to either redistribute and/or
* modify this file, provided that the conditions mentioned in the
* file COPYING are met. Consult the file for details.
* @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
* implementation details. Don't take them as canon. They could
* rapidly appear then vanish. The name (path) of this header file
* is also an implementation detail. Do not expect it to persist
* at the place it is now. Developers are free to move it anywhere
* anytime at will.
* @note To ruby-core: remember that this header can be possibly
* recursively included from extension libraries written in C++.
* Do not expect for instance `__VA_ARGS__` is always available.
* We assume C99 for ruby itself but we don't assume languages of
* extension libraries. They could be written in C++98.
* @brief Arithmetic conversion between C's `st_data_t` and Ruby's.
*/
#include "ruby/internal/arithmetic/fixnum.h"
#include "ruby/internal/arithmetic/long.h"
#include "ruby/internal/attr/artificial.h"
#include "ruby/internal/attr/const.h"
#include "ruby/internal/attr/constexpr.h"
#include "ruby/internal/cast.h"
#include "ruby/internal/value.h"
#include "ruby/assert.h"
#include "ruby/st.h"
#define ST2FIX RB_ST2FIX /**< @old{RB_ST2FIX} */
/** @cond INTERNAL_MACRO */
#define RB_ST2FIX RB_ST2FIX
/** @endcond */
RBIMPL_ATTR_CONST_UNLESS_DEBUG()
RBIMPL_ATTR_CONSTEXPR_UNLESS_DEBUG(CXX14)
RBIMPL_ATTR_ARTIFICIAL()
/**
* Converts a C's `st_data_t` into an instance of ::rb_cInteger.
*
* @param[in] i The data in question.
* @return A converted result
* @warning THIS CONVERSION LOSES DATA! Be warned.
* @see https://bugs.ruby-lang.org/issues/13877
* @see https://bugs.ruby-lang.org/issues/14218
*
* @internal
*
* This is needed because of hash functions. Hash functions return
* `st_data_t`, which could theoretically be bigger than Fixnums. However
* allocating Bignums for them every time we calculate hash values is just too
* heavy. To avoid penalty we need to ignore some upper bit(s) and stick to
* Fixnums. This function is used for that purpose.
*/
static inline VALUE
RB_ST2FIX(st_data_t i)
{
SIGNED_VALUE x = i;
if (x >= 0) {
x &= RUBY_FIXNUM_MAX;
}
else {
x |= RUBY_FIXNUM_MIN;
}
RBIMPL_ASSERT_OR_ASSUME(RB_FIXABLE(x));
unsigned long y = RBIMPL_CAST((unsigned long)x);
return RB_LONG2FIX(y);
}
#endif /* RBIMPL_ARITHMETIC_ST_DATA_T_H */