int main(void){
long char_min, short_min, int_min;
long long_min;
float float_min;
long char_max, short_max, int_max;
long long_max;
float float_max;
/* range of char */
printf ("header:range of char is %d - %d\n", CHAR_MIN, CHAR_MAX);
char_max = get_max_by_size(sizeof(char));
char_min = get_min_by_max(char_max);
printf ("compute:range of char is %ld - %ld\n", char_min, char_max);
/* range of int */
printf ("header:range of int is %d - %d\n", INT_MIN, INT_MAX);
int_max = get_max_by_size(sizeof(int));
int_min = get_min_by_max(int_max);
printf ("compute:range of int is %ld - %ld\n", int_min, int_max);
/* range of short */
printf ("header:range of short is %d - %d\n", SHRT_MIN, SHRT_MAX);
short_max = get_max_by_size(sizeof(short));
short_min = get_min_by_max(short_max);
printf ("compute:range of long is %ld - %ld\n", short_min, short_max);
/* range of long */
printf ("header:range of long is %ld - %ld\n", LONG_MIN, LONG_MAX);
long_max = get_max_by_size(sizeof(long));
long_min = get_min_by_max(long_max);
printf ("compute:range of long is %ld - %ld\n", long_min, long_max);
/* range of float */
printf ("header:range of float is %f - %f\n", FLT_MIN, FLT_MAX);
float_max = get_max_float();
printf ("header:range of float is %f - %f\n", FLT_MIN, float_max);
return 0;
}
/* Define the float.h constants for TYPE using NAME_PREFIX, FP_SUFFIX,
and FP_CAST. */
static void
builtin_define_float_constants (const char *name_prefix,
const char *fp_suffix,
const char *fp_cast,
const char *fma_suffix,
tree type)
{
/* Used to convert radix-based values to base 10 values in several cases.
In the max_exp -> max_10_exp conversion for 128-bit IEEE, we need at
least 6 significant digits for correct results. Using the fraction
formed by (log(2)*1e6)/(log(10)*1e6) overflows a 32-bit integer as an
intermediate; perhaps someone can find a better approximation, in the
mean time, I suspect using doubles won't harm the bootstrap here. */
const double log10_2 = .30102999566398119521;
double log10_b;
const struct real_format *fmt;
const struct real_format *ldfmt;
char name[64], buf[128];
int dig, min_10_exp, max_10_exp;
int decimal_dig;
int type_decimal_dig;
fmt = REAL_MODE_FORMAT (TYPE_MODE (type));
gcc_assert (fmt->b != 10);
ldfmt = REAL_MODE_FORMAT (TYPE_MODE (long_double_type_node));
gcc_assert (ldfmt->b != 10);
/* The radix of the exponent representation. */
if (type == float_type_node)
builtin_define_with_int_value ("__FLT_RADIX__", fmt->b);
log10_b = log10_2;
/* The number of radix digits, p, in the floating-point significand. */
sprintf (name, "__%s_MANT_DIG__", name_prefix);
builtin_define_with_int_value (name, fmt->p);
/* The number of decimal digits, q, such that any floating-point number
with q decimal digits can be rounded into a floating-point number with
p radix b digits and back again without change to the q decimal digits,
p log10 b if b is a power of 10
floor((p - 1) log10 b) otherwise
*/
dig = (fmt->p - 1) * log10_b;
sprintf (name, "__%s_DIG__", name_prefix);
builtin_define_with_int_value (name, dig);
/* The minimum negative int x such that b**(x-1) is a normalized float. */
sprintf (name, "__%s_MIN_EXP__", name_prefix);
sprintf (buf, "(%d)", fmt->emin);
builtin_define_with_value (name, buf, 0);
/* The minimum negative int x such that 10**x is a normalized float,
ceil (log10 (b ** (emin - 1)))
= ceil (log10 (b) * (emin - 1))
Recall that emin is negative, so the integer truncation calculates
the ceiling, not the floor, in this case. */
min_10_exp = (fmt->emin - 1) * log10_b;
sprintf (name, "__%s_MIN_10_EXP__", name_prefix);
sprintf (buf, "(%d)", min_10_exp);
builtin_define_with_value (name, buf, 0);
/* The maximum int x such that b**(x-1) is a representable float. */
sprintf (name, "__%s_MAX_EXP__", name_prefix);
builtin_define_with_int_value (name, fmt->emax);
/* The maximum int x such that 10**x is in the range of representable
finite floating-point numbers,
floor (log10((1 - b**-p) * b**emax))
= floor (log10(1 - b**-p) + log10(b**emax))
= floor (log10(1 - b**-p) + log10(b)*emax)
The safest thing to do here is to just compute this number. But since
we don't link cc1 with libm, we cannot. We could implement log10 here
a series expansion, but that seems too much effort because:
Note that the first term, for all extant p, is a number exceedingly close
to zero, but slightly negative. Note that the second term is an integer
scaling an irrational number, and that because of the floor we are only
interested in its integral portion.
In order for the first term to have any effect on the integral portion
of the second term, the second term has to be exceedingly close to an
integer itself (e.g. 123.000000000001 or something). Getting a result
that close to an integer requires that the irrational multiplicand have
a long series of zeros in its expansion, which doesn't occur in the
first 20 digits or so of log10(b).
Hand-waving aside, crunching all of the sets of constants above by hand
does not yield a case for which the first term is significant, which
in the end is all that matters. */
max_10_exp = fmt->emax * log10_b;
sprintf (name, "__%s_MAX_10_EXP__", name_prefix);
builtin_define_with_int_value (name, max_10_exp);
/* The number of decimal digits, n, such that any floating-point number
can be rounded to n decimal digits and back again without change to
the value.
p * log10(b) if b is a power of 10
ceil(1 + p * log10(b)) otherwise
The only macro we care about is this number for the widest supported
floating type, but we want this value for rendering constants below. */
{
double d_decimal_dig
= 1 + (fmt->p < ldfmt->p ? ldfmt->p : fmt->p) * log10_b;
decimal_dig = d_decimal_dig;
if (decimal_dig < d_decimal_dig)
decimal_dig++;
}
/* Similar, for this type rather than long double. */
{
double type_d_decimal_dig = 1 + fmt->p * log10_b;
type_decimal_dig = type_d_decimal_dig;
if (type_decimal_dig < type_d_decimal_dig)
type_decimal_dig++;
}
if (type == long_double_type_node)
builtin_define_with_int_value ("__DECIMAL_DIG__", decimal_dig);
else
{
sprintf (name, "__%s_DECIMAL_DIG__", name_prefix);
builtin_define_with_int_value (name, type_decimal_dig);
}
/* Since, for the supported formats, B is always a power of 2, we
construct the following numbers directly as a hexadecimal
constants. */
get_max_float (fmt, buf, sizeof (buf));
sprintf (name, "__%s_MAX__", name_prefix);
builtin_define_with_hex_fp_value (name, type, decimal_dig, buf, fp_suffix, fp_cast);
/* The minimum normalized positive floating-point number,
b**(emin-1). */
sprintf (name, "__%s_MIN__", name_prefix);
sprintf (buf, "0x1p%d", fmt->emin - 1);
builtin_define_with_hex_fp_value (name, type, decimal_dig, buf, fp_suffix, fp_cast);
/* The difference between 1 and the least value greater than 1 that is
representable in the given floating point type, b**(1-p). */
sprintf (name, "__%s_EPSILON__", name_prefix);
if (fmt->pnan < fmt->p)
/* This is an IBM extended double format, so 1.0 + any double is
representable precisely. */
sprintf (buf, "0x1p%d", fmt->emin - fmt->p);
else
sprintf (buf, "0x1p%d", 1 - fmt->p);
builtin_define_with_hex_fp_value (name, type, decimal_dig, buf, fp_suffix, fp_cast);
/* For C++ std::numeric_limits<T>::denorm_min. The minimum denormalized
positive floating-point number, b**(emin-p). Zero for formats that
don't support denormals. */
sprintf (name, "__%s_DENORM_MIN__", name_prefix);
if (fmt->has_denorm)
{
sprintf (buf, "0x1p%d", fmt->emin - fmt->p);
builtin_define_with_hex_fp_value (name, type, decimal_dig,
buf, fp_suffix, fp_cast);
}
else
{
sprintf (buf, "0.0%s", fp_suffix);
builtin_define_with_value (name, buf, 0);
}
sprintf (name, "__%s_HAS_DENORM__", name_prefix);
builtin_define_with_value (name, fmt->has_denorm ? "1" : "0", 0);
/* For C++ std::numeric_limits<T>::has_infinity. */
sprintf (name, "__%s_HAS_INFINITY__", name_prefix);
builtin_define_with_int_value (name,
MODE_HAS_INFINITIES (TYPE_MODE (type)));
/* For C++ std::numeric_limits<T>::has_quiet_NaN. We do not have a
predicate to distinguish a target that has both quiet and
signalling NaNs from a target that has only quiet NaNs or only
signalling NaNs, so we assume that a target that has any kind of
NaN has quiet NaNs. */
sprintf (name, "__%s_HAS_QUIET_NAN__", name_prefix);
builtin_define_with_int_value (name, MODE_HAS_NANS (TYPE_MODE (type)));
/* Note whether we have fast FMA. */
if (mode_has_fma (TYPE_MODE (type)))
{
sprintf (name, "__FP_FAST_FMA%s", fma_suffix);
builtin_define_with_int_value (name, 1);
}
}
