MIN_EXP
#define HEXNDIG ((MAX_EXP - MIN_EXP + 7) / 8 + 2 * MANT_DIG)
if (exponent < MIN_EXP - 1)
mp_size_t shift = MIN_EXP - 1 - exponent;
# define DENORM_EXP (MIN_EXP - 2)
exponent = MIN_EXP - 1;
-MIN_EXP + MANT_DIG + 4 * int_no :