static int f2s_buffered_n(float f, Span <char> result)
{
// Step 1: Decode the floating-point number, and unify normalized and subnormal cases.
uint bits = float_to_bits(f);
// Decode bits into sign, mantissa, and exponent.
bool ieeeSign = ((bits >> (FLOAT_MANTISSA_BITS + FLOAT_EXPONENT_BITS)) & 1) != 0;
uint ieeeMantissa = bits & ((1u << FLOAT_MANTISSA_BITS) - 1);
uint ieeeExponent = (bits >> FLOAT_MANTISSA_BITS) & ((1u << FLOAT_EXPONENT_BITS) - 1);
// Case distinction; exit early for the easy cases.
if (ieeeExponent == ((1u << FLOAT_EXPONENT_BITS) - 1u) || (ieeeExponent == 0 && ieeeMantissa == 0))
{
return(copy_special_str(result, ieeeSign, Convert.ToBoolean(ieeeExponent), Convert.ToBoolean(ieeeMantissa)));
}
floating_decimal_32 v = f2d(ieeeMantissa, ieeeExponent);
return(to_chars(v, ieeeSign, result));
}
static int to_chars(floating_decimal_32 v, bool sign, Span <char> result)
{
// Step 5: Print the decimal representation.
int index = 0;
if (sign)
{
result[index++] = '-';
}
uint output = v.mantissa;
int olength = decimalLength9(output);
// Print the decimal digits.
// The following code is equivalent to:
// for (uint i = 0; i < olength - 1; ++i) {
// uint c = output % 10; output /= 10;
// result[index + olength - i] = (char) ('0' + c);
// }
// result[index] = '0' + output % 10;
int i = 0;
while (output >= 10000)
{
uint c = output % 10000;
output /= 10000;
uint c0 = (c % 100) << 1;
uint c1 = (c / 100) << 1;
memcpy(result.Slice(index + olength - i - 1), DIGIT_TABLE, c0, 2);
memcpy(result.Slice(index + olength - i - 3), DIGIT_TABLE, c1, 2);
i += 4;
}
if (output >= 100)
{
uint c = (output % 100) << 1;
output /= 100;
memcpy(result.Slice(index + olength - i - 1), DIGIT_TABLE, c, 2);
i += 2;
}
if (output >= 10)
{
uint c = output << 1;
// We can't use memcpy here: the decimal dot goes between these two digits.
result[index + olength - i] = DIGIT_TABLE[c + 1];
result[index] = DIGIT_TABLE[c];
}
else
{
result[index] = (char)('0' + output);
}
// Print decimal point if needed.
if (olength > 1)
{
result[index + 1] = '.';
index += olength + 1;
}
else
{
++index;
}
// Print the exponent.
result[index++] = 'E';
int exp = v.exponent + (int)olength - 1;
if (exp < 0)
{
result[index++] = '-';
exp = -exp;
}
if (exp >= 10)
{
memcpy(result.Slice(index), DIGIT_TABLE, 2 * exp, 2);
index += 2;
}
else
{
result[index++] = (char)('0' + exp);
}
return(index);
}