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add function for checked mrb_int addition

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cremno
2014-05-05 15:24:22 +02:00
parent ff03cea79b
commit 0f39304265
3 changed files with 15 additions and 12 deletions
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include/mruby/numeric.h
+10
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@@ -35,6 +35,16 @@ mrb_float mrb_to_flo(mrb_state *mrb, mrb_value x);
# define MRB_INT_OVERFLOW_MASK ((mrb_uint)1 << (MRB_INT_BIT - 1))
#endif
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);
}
#undef MRB_INT_OVERFLOW_MASK
#undef mrb_uint
#undef MRB_UINT_MAKE