numeric.h

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#ifndef MRUBY_NUMERIC_H
#define MRUBY_NUMERIC_H

#include "common.h"

MRB_BEGIN_DECL

#define TYPED_POSFIXABLE(f,t) ((f) <= (t)MRB_INT_MAX)
#define TYPED_NEGFIXABLE(f,t) ((f) >= (t)MRB_INT_MIN)
#define TYPED_FIXABLE(f,t) (TYPED_POSFIXABLE(f,t) && TYPED_NEGFIXABLE(f,t))
#define POSFIXABLE(f) TYPED_POSFIXABLE(f,mrb_int)
#define NEGFIXABLE(f) TYPED_NEGFIXABLE(f,mrb_int)
#define FIXABLE(f) TYPED_FIXABLE(f,mrb_int)
#ifndef MRB_WITHOUT_FLOAT
#ifdef MRB_INT64
#define FIXABLE_FLOAT(f) ((f)>=-9223372036854775808.0 && (f)<9223372036854775808.0)
#else
#define FIXABLE_FLOAT(f) TYPED_FIXABLE(f,mrb_float)
#endif
#endif

#ifndef MRB_WITHOUT_FLOAT
MRB_API mrb_value mrb_flo_to_fixnum(mrb_state *mrb, mrb_value val);
#endif
MRB_API mrb_value mrb_fixnum_to_str(mrb_state *mrb, mrb_value x, mrb_int base);
/* ArgumentError if format string doesn't match /%(\.[0-9]+)?[aAeEfFgG]/ */
#ifndef MRB_WITHOUT_FLOAT
MRB_API mrb_value mrb_float_to_str(mrb_state *mrb, mrb_value x, const char *fmt);
MRB_API mrb_float mrb_to_flo(mrb_state *mrb, mrb_value x);
MRB_API mrb_value mrb_int_value(mrb_state *mrb, mrb_float f);
#endif

MRB_API mrb_value mrb_num_plus(mrb_state *mrb, mrb_value x, mrb_value y);
MRB_API mrb_value mrb_num_minus(mrb_state *mrb, mrb_value x, mrb_value y);
MRB_API mrb_value mrb_num_mul(mrb_state *mrb, mrb_value x, mrb_value y);

#ifndef __has_builtin
  #define __has_builtin(x) 0
#endif

#if (defined(__GNUC__) && __GNUC__ >= 5) ||   \
    (__has_builtin(__builtin_add_overflow) && \
     __has_builtin(__builtin_sub_overflow) && \
     __has_builtin(__builtin_mul_overflow))
# define MRB_HAVE_TYPE_GENERIC_CHECKED_ARITHMETIC_BUILTINS
#endif

/*
// Clang 3.8 and 3.9 have problem compiling mruby in 32-bit mode, when MRB_INT64 is set
// because of missing __mulodi4 and similar functions in its runtime. We need to use custom
// implementation for them.
*/
#ifdef MRB_HAVE_TYPE_GENERIC_CHECKED_ARITHMETIC_BUILTINS
#if defined(__clang__) && (__clang_major__ == 3) && (__clang_minor__ >= 8) && \
    defined(MRB_32BIT) && defined(MRB_INT64)
#undef MRB_HAVE_TYPE_GENERIC_CHECKED_ARITHMETIC_BUILTINS
#endif
#endif

#ifdef MRB_HAVE_TYPE_GENERIC_CHECKED_ARITHMETIC_BUILTINS

#ifndef MRB_WORD_BOXING
# define WBCHK(x) 0
#else
# define WBCHK(x) !FIXABLE(x)
#endif

static inline mrb_bool
mrb_int_add_overflow(mrb_int augend, mrb_int addend, mrb_int *sum)
{
  return __builtin_add_overflow(augend, addend, sum) || WBCHK(*sum);
}

static inline mrb_bool
mrb_int_sub_overflow(mrb_int minuend, mrb_int subtrahend, mrb_int *difference)
{
  return __builtin_sub_overflow(minuend, subtrahend, difference) || WBCHK(*difference);
}

static inline mrb_bool
mrb_int_mul_overflow(mrb_int multiplier, mrb_int multiplicand, mrb_int *product)
{
  return __builtin_mul_overflow(multiplier, multiplicand, product) || WBCHK(*product);
}

#undef WBCHK

#else

#define MRB_UINT_MAKE2(n) uint ## n ## _t
#define MRB_UINT_MAKE(n) MRB_UINT_MAKE2(n)
#define mrb_uint MRB_UINT_MAKE(MRB_INT_BIT)

#define MRB_INT_OVERFLOW_MASK ((mrb_uint)1 << (MRB_INT_BIT - 1 - MRB_FIXNUM_SHIFT))

static inline mrb_bool
mrb_int_add_overflow(mrb_int augend, mrb_int addend, mrb_int *sum)
{
  mrb_uint x = (mrb_uint)augend;
  mrb_uint y = (mrb_uint)addend;
  mrb_uint z = (mrb_uint)(x + y);
  *sum = (mrb_int)z;
  return !!(((x ^ z) & (y ^ z)) & MRB_INT_OVERFLOW_MASK);
}

static inline mrb_bool
mrb_int_sub_overflow(mrb_int minuend, mrb_int subtrahend, mrb_int *difference)
{
  mrb_uint x = (mrb_uint)minuend;
  mrb_uint y = (mrb_uint)subtrahend;
  mrb_uint z = (mrb_uint)(x - y);
  *difference = (mrb_int)z;
  return !!(((x ^ z) & (~y ^ z)) & MRB_INT_OVERFLOW_MASK);
}

static inline mrb_bool
mrb_int_mul_overflow(mrb_int multiplier, mrb_int multiplicand, mrb_int *product)
{
#if MRB_INT_BIT == 32
  int64_t n = (int64_t)multiplier * multiplicand;
  *product = (mrb_int)n;
  return !FIXABLE(n);
#else
  if (multiplier > 0) {
    if (multiplicand > 0) {
      if (multiplier > MRB_INT_MAX / multiplicand) return TRUE;
    }
    else {
      if (multiplicand < MRB_INT_MAX / multiplier) return TRUE;
    }
  }
  else {
    if (multiplicand > 0) {
      if (multiplier < MRB_INT_MAX / multiplicand) return TRUE;
    }
    else {
      if (multiplier != 0 && multiplicand < MRB_INT_MAX / multiplier) return TRUE;
    }
  }
  *product = multiplier * multiplicand;
  return FALSE;
#endif
}

#undef MRB_INT_OVERFLOW_MASK
#undef mrb_uint
#undef MRB_UINT_MAKE
#undef MRB_UINT_MAKE2

#endif

#ifndef MRB_WITHOUT_FLOAT
# include <stdint.h>
# include <float.h>

# define MRB_FLT_RADIX          FLT_RADIX

# ifdef MRB_USE_FLOAT
#  define MRB_FLT_MANT_DIG      FLT_MANT_DIG
#  define MRB_FLT_EPSILON       FLT_EPSILON
#  define MRB_FLT_DIG           FLT_DIG
#  define MRB_FLT_MIN_EXP       FLT_MIN_EXP
#  define MRB_FLT_MIN           FLT_MIN
#  define MRB_FLT_MIN_10_EXP    FLT_MIN_10_EXP
#  define MRB_FLT_MAX_EXP       FLT_MAX_EXP
#  define MRB_FLT_MAX           FLT_MAX
#  define MRB_FLT_MAX_10_EXP    FLT_MAX_10_EXP

# else /* not MRB_USE_FLOAT */
#  define MRB_FLT_MANT_DIG      DBL_MANT_DIG
#  define MRB_FLT_EPSILON       DBL_EPSILON
#  define MRB_FLT_DIG           DBL_DIG
#  define MRB_FLT_MIN_EXP       DBL_MIN_EXP
#  define MRB_FLT_MIN           DBL_MIN
#  define MRB_FLT_MIN_10_EXP    DBL_MIN_10_EXP
#  define MRB_FLT_MAX_EXP       DBL_MAX_EXP
#  define MRB_FLT_MAX           DBL_MAX
#  define MRB_FLT_MAX_10_EXP    DBL_MAX_10_EXP
# endif /* MRB_USE_FLOAT */
#endif /* MRB_WITHOUT_FLOAT */

MRB_END_DECL

#endif  /* MRUBY_NUMERIC_H */