/// <summary>
/// Converts a single precision floating point number to a string.
/// </summary>
/// <param name="result">The location where the result will be placed.</param>
/// <param name="value">The value to format.</param>
/// <param name="precision">The precision to output when formatting.</param>
/// <param name="options">The format mode to use.</param>
/// <param name="provider">The provider used to determine how the value will be
/// formatted.</param>
public static void ToString(StringBuilder result, float value, int precision,
RyuFormatOptions options = RyuFormatOptions.RoundtripMode,
IFormatProvider provider = null)
{
var info = RyuUtils.GetFormatInfo(provider);
// Step 1: Decode the floating-point number, and unify normalized and subnormal
// cases
bool ieeeSign = RyuFloat32.Decode(value, out uint ieeeMantissa,
out uint ieeeExponent);
// Case distinction; exit early for the easy cases
bool mZero = ieeeMantissa == 0UL;
if (ieeeExponent == RyuFloat32.EXPONENT_MASK)
{
RyuUtils.GenerateSpecial(result, ieeeSign, !mZero, info);
}
else if (mZero && ieeeExponent == 0UL)
{
RyuUtils.GenerateZero(result, ieeeSign, precision, options, info);
}
else if ((options & RyuFormatOptions.RoundtripMode) != 0)
{
new RyuFloat32(ieeeSign, ieeeMantissa, ieeeExponent).ToRoundtripString(result,
options, info);
}
}
/// <summary>
/// Appends the exponent for exponential and roundtrip notation.
/// </summary>
internal static void AppendExponent(StringBuilder result, int exponent,
RyuFormatOptions options, NumberFormatInfo info)
{
bool compat = (options & RyuFormatOptions.CompatibleExponent) != 0;
#if DEBUG
if (exponent < -9999 || exponent > 9999)
{
throw new ArgumentOutOfRangeException(nameof(exponent), exponent,
"4 digit exponent limit");
}
#endif
result.Append('E');
if (exponent < 0)
{
result.Append(info.NegativeSign);
exponent = -exponent;
}
else if (compat || (options & RyuFormatOptions.ExponentialMode) != 0)
{
result.Append(info.PositiveSign);
}
if (exponent >= 100)
{
int e100 = exponent / 100;
if (e100 >= 10)
{
result.Append(RyuTables.DIGIT_TABLE[e100]);
}
else
{
result.Append(e100.DigitToChar());
}
result.Append(RyuTables.DIGIT_TABLE[exponent - 100 * e100]);
}
else
{
if (compat)
{
result.Append(ZERO);
}
if (exponent >= 10)
{
result.Append(RyuTables.DIGIT_TABLE[exponent]);
}
else
{
if (compat)
{
result.Append(ZERO);
}
result.Append(exponent.DigitToChar());
}
}
}
/// <summary>
/// Generates the output for positive (and negative) zero.
/// </summary>
internal static void GenerateZero(StringBuilder result, bool sign, int precision,
RyuFormatOptions options, NumberFormatInfo info)
{
bool compat = (options & RyuFormatOptions.CompatibleExponent) != 0, hard =
precision > 0 && (options & RyuFormatOptions.SoftPrecision) == 0;
if ((options & RyuFormatOptions.RoundtripMode) != 0)
{
// Roundtrip mode just needs +0 or -0
if (sign)
{
result.Append("-");
}
if (compat)
{
result.Append("0E+000");
}
else
{
result.Append("0E0");
}
}
else if ((options & RyuFormatOptions.ExponentialMode) != 0)
{
// Exponential mode
result.Append(ZERO);
if (hard)
{
result.Append(info.NumberDecimalSeparator);
Append0(result, precision);
}
if (compat)
{
result.Append("E+000");
}
else
{
result.Append("E0");
}
}
else
{
// Fixed mode
result.Append(ZERO);
if (hard)
{
result.Append(info.NumberDecimalSeparator);
Append0(result, precision);
}
}
}
/// <summary>
/// Convert a 32-bit Ryu floating point number to a roundtrip notation string.
/// </summary>
public void ToRoundtripString(StringBuilder result, RyuFormatOptions options,
NumberFormatInfo info = null)
{
// Step 5: Print the decimal representation
if (info == null)
{
info = CultureInfo.CurrentCulture.NumberFormat;
}
if (sign)
{
result.Append(info.NegativeSign);
}
#if DEBUG
if (info.NumberDecimalSeparator.Length > 1)
{
throw new ArgumentException("Requires a single character decimal point");
}
#endif
// Print the decimal digits
uint mantissa = this.mantissa;
int olength = RyuUtils.DecimalLength9(mantissa), start = result.Length, index =
olength + start;
result.Length = index + 1;
index = RyuUtils.PrintGroups42(result, ref mantissa, index);
// Group of 1
if (mantissa >= 10U)
{
string digits = RyuTables.DIGIT_TABLE[mantissa];
// We can't use memcpy here: the decimal dot goes between these two digits
result[index--] = digits[1];
result[start] = digits[0];
}
else
{
result[start] = mantissa.DigitToChar();
}
// Print decimal point if needed
if (olength > 1)
{
result[start + 1] = info.NumberDecimalSeparator[0];
index += olength;
}
result.Length = index;
RyuUtils.AppendExponent(result, exponent + olength - 1, options, info);
}
/// <summary>
/// Convert a 64-bit Ryu floating point number to a roundtrip notation string.
/// </summary>
public void ToRoundtripString(StringBuilder result, RyuFormatOptions options,
NumberFormatInfo info = null)
{
// Step 5: Print the decimal representation
if (info == null)
{
info = CultureInfo.CurrentCulture.NumberFormat;
}
if (sign)
{
result.Append(info.NegativeSign);
}
#if DEBUG
if (info.NumberDecimalSeparator.Length > 1)
{
throw new ArgumentException("Requires a single character decimal point");
}
#endif
ulong mantissa = this.mantissa;
uint mantissaShort;
int olength = RyuUtils.DecimalLength17(mantissa), start = result.Length, index =
olength + start;
result.Length = index + 1;
// Print the decimal digits: group of 8
if ((mantissa >> 32) != 0U)
{
// We prefer 32-bit operations, even on 64-bit platforms.
// We have at most 17 digits, and uint can store 9 digits.
// If output doesn't fit into uint, we cut off 8 digits,
// so the rest will fit into uint
ulong q = mantissa / 100000000UL;
mantissaShort = (uint)mantissa - 100000000U * (uint)q;
uint o10000 = mantissaShort / 10000U;
uint c0 = mantissaShort - 10000U * o10000, d0 = o10000 % 10000U;
uint c1 = c0 / 100U, d1 = d0 / 100U;
mantissa = q;
index = result.WriteDigits(index, c0 - 100U * c1);
index = result.WriteDigits(index, c1);
index = result.WriteDigits(index, d0 - 100U * d1);
index = result.WriteDigits(index, d1);
}
mantissaShort = (uint)mantissa;
index = RyuUtils.PrintGroups42(result, ref mantissaShort, index);
// Group of 1
if (mantissaShort >= 10U)
{
string digits = RyuTables.DIGIT_TABLE[mantissaShort];
// We can't use memcpy here: the decimal dot goes between these two digits
result[index--] = digits[1];
result[start] = digits[0];
}
else
{
result[start] = mantissaShort.DigitToChar();
}
// Print decimal point if needed
if (olength > 1)
{
result[start + 1] = info.NumberDecimalSeparator[0];
index += olength;
}
result.Length = index;
RyuUtils.AppendExponent(result, exponent + olength - 1, options, info);
}
/// <summary>
/// Convert a 64-bit floating point number to an exponential notation string.
/// </summary>
internal static void ToExponentialString(StringBuilder result, ulong ieeeMantissa,
uint ieeeExponent, int precision, RyuFormatOptions options,
NumberFormatInfo info)
{
bool printDP = precision > 0, soft = (options & RyuFormatOptions.SoftPrecision) !=
0;
uint digits = 0U;
int printedDigits = 0, availDigits = 0, exp = 0, exponent = Decode(ieeeMantissa,
ieeeExponent, out ulong mantissa), start = result.Length;
ulong mantShift = mantissa << MANTISSA_SHIFT;
++precision;
if (exponent >= -RyuFloat64.DOUBLE_MANTISSA_BITS)
{
int idx = (exponent < 0) ? 0 : RyuUtils.IndexForExponent(exponent), i =
RyuUtils.LengthForIndex(idx) - 1, j = Pow10BitsForIndex(idx) - exponent +
MANTISSA_SHIFT, p = RyuTables.POW10_OFFSET_D[idx] + i;
for (; i >= 0; i--)
{
// Temporary: j is usually around 128, and by shifting a bit, we push it
// to 128 or above, which is a slightly faster code path in
// MulShiftMod1E9. Instead, we can just increase the multipliers
digits = RyuUtils.MulShiftMod1E9(mantShift, RyuTables.POW10_SPLIT_D[p, 0],
RyuTables.POW10_SPLIT_D[p, 1], RyuTables.POW10_SPLIT_D[p, 2], j);
if (printedDigits > 0)
{
if (printedDigits + 9 > precision)
{
availDigits = 9;
break;
}
RyuUtils.Append9Digits(result, digits);
printedDigits += 9;
}
else if (digits != 0U)
{
availDigits = RyuUtils.DecimalLength9(digits);
exp = i * 9 + availDigits - 1;
if (availDigits > precision)
{
break;
}
RyuUtils.AppendDDigits(result, digits, availDigits + 1, printDP, info);
printedDigits = availDigits;
availDigits = 0;
}
p--;
}
}
if (exponent < 0 && availDigits == 0)
{
int idx = (-exponent) >> 4, pMax = RyuTables.POW10_OFFSET_2_D[idx + 1], p =
RyuTables.POW10_OFFSET_2_D[idx], j = MANTISSA_SHIFT +
POW10_ADDITIONAL_BITS - exponent - (idx << 4);
for (int i = RyuTables.MIN_BLOCK_2_D[idx]; i < 200; i++)
{
digits = (p >= pMax) ? 0U : RyuUtils.MulShiftMod1E9(mantShift,
RyuTables.POW10_SPLIT_2_D[p, 0], RyuTables.POW10_SPLIT_2_D[p, 1],
RyuTables.POW10_SPLIT_2_D[p, 2], j);
if (printedDigits > 0)
{
if (printedDigits + 9 > precision)
{
availDigits = 9;
break;
}
RyuUtils.Append9Digits(result, digits);
printedDigits += 9;
}
else if (digits != 0)
{
availDigits = RyuUtils.DecimalLength9(digits);
exp = (i + 1) * -9 + availDigits - 1;
if (availDigits > precision)
{
break;
}
RyuUtils.AppendDDigits(result, digits, availDigits + 1, printDP, info);
printedDigits = availDigits;
availDigits = 0;
}
p++;
}
}
// 0 = don't round up; 1 = round up unconditionally; 2 = round up if odd
int maxDigits = precision - printedDigits, roundFlag;
uint lastDigit = 0U;
if (availDigits == 0)
{
digits = 0U;
}
if (availDigits > maxDigits)
{
lastDigit = RyuUtils.LastDigit(ref digits, availDigits - maxDigits);
}
if (lastDigit != 5U)
{
roundFlag = (lastDigit > 5U) ? 1 : 0;
}
else
{
// Is m * 2^e2 * 10^(precision + 1 - exp) integer?
// precision was already increased by 1, so we don't need to write + 1 here.
int rexp = precision - exp;
bool trailingZeroes = HasTrailingZeroes(exponent, rexp, mantissa);
if (rexp < 0 && trailingZeroes)
{
trailingZeroes = RyuUtils.IsMultipleOf5Power(mantissa, -rexp);
}
roundFlag = trailingZeroes ? 2 : 1;
}
if (printedDigits > 0)
{
if (digits == 0U)
{
if (!soft)
{
RyuUtils.Append0(result, maxDigits);
}
}
else
{
RyuUtils.AppendCDigits(result, digits, maxDigits);
}
}
else
{
RyuUtils.AppendDDigits(result, digits, maxDigits + 1, printDP, info);
}
if (roundFlag != 0 && RyuUtils.RoundResult(result, start, roundFlag, out _, info))
{
exp++;
}
if (soft)
{
RyuUtils.SoftenResult(result, info);
}
RyuUtils.AppendExponent(result, exp, options, info);
}
/// <summary>
/// Convert a 64-bit floating point number to a fixed notation string.
/// </summary>
internal static void ToFixedString(StringBuilder result, ulong ieeeMantissa,
uint ieeeExponent, int precision, RyuFormatOptions options,
NumberFormatInfo info)
{
bool zero = true, soft = (options & RyuFormatOptions.SoftPrecision) != 0;
int exponent = Decode(ieeeMantissa, ieeeExponent, out ulong mantissa), start =
result.Length;
ulong mShift = mantissa << MANTISSA_SHIFT;
uint digits;
if (exponent >= -RyuFloat64.DOUBLE_MANTISSA_BITS)
{
int idx = (exponent < 0) ? 0 : RyuUtils.IndexForExponent(exponent), p10bits =
Pow10BitsForIndex(idx), i = RyuUtils.LengthForIndex(idx) - 1, p =
RyuTables.POW10_OFFSET_D[idx] + i, j = p10bits - exponent + MANTISSA_SHIFT;
for (; i >= 0; i--)
{
digits = RyuUtils.MulShiftMod1E9(mShift, RyuTables.POW10_SPLIT_D[p, 0],
RyuTables.POW10_SPLIT_D[p, 1], RyuTables.POW10_SPLIT_D[p, 2], j);
if (!zero)
{
RyuUtils.Append9Digits(result, digits);
}
else if (digits != 0U)
{
RyuUtils.AppendNDigits(result, RyuUtils.DecimalLength9(digits),
digits);
zero = false;
}
p--;
}
}
if (zero)
{
result.Append(RyuUtils.ZERO);
}
if ((options & RyuFormatOptions.ThousandsSeparators) != 0)
{
RyuUtils.AddThousands(result, start, info);
}
if (precision > 0 && (!soft || exponent < 0))
{
result.Append(info.NumberDecimalSeparator);
}
if (exponent < 0)
{
// 0 = don't round up; 1 = round up unconditionally; 2 = round up if odd
int idx = (-exponent) >> 4, roundFlag = 0, i = 0, blocks = precision / 9 + 1,
minBlock = RyuTables.MIN_BLOCK_2_D[idx];
if (blocks <= minBlock)
{
RyuUtils.Append0(result, precision);
i = blocks;
}
else if (i < minBlock)
{
RyuUtils.Append0(result, 9 * minBlock);
i = minBlock;
}
int p = RyuTables.POW10_OFFSET_2_D[idx] + i - minBlock, pMax = RyuTables.
POW10_OFFSET_2_D[idx + 1], j = MANTISSA_SHIFT + POW10_ADDITIONAL_BITS -
exponent - (idx << 4);
for (; i < blocks; ++i)
{
if (p >= pMax)
{
// If the remaining digits are all 0, then no rounding required
if (!soft)
{
RyuUtils.Append0(result, precision - 9 * i);
}
break;
}
digits = RyuUtils.MulShiftMod1E9(mShift, RyuTables.POW10_SPLIT_2_D[p, 0],
RyuTables.POW10_SPLIT_2_D[p, 1], RyuTables.POW10_SPLIT_2_D[p, 2], j);
if (i < blocks - 1)
{
RyuUtils.Append9Digits(result, digits);
}
else
{
int maximum = precision - 9 * i;
uint lastDigit = RyuUtils.LastDigit(ref digits, 9 - maximum);
// Is m * 10^(additionalDigits + 1) / 2^(-e2) integer?
if (lastDigit > 5U)
{
roundFlag = 1;
}
else if (lastDigit < 5U)
{
roundFlag = 0;
}
else if (HasTrailingZeroes(exponent, precision + 1, mantissa))
{
roundFlag = 2;
}
else
{
roundFlag = 1;
}
if (maximum > 0)
{
RyuUtils.AppendCDigits(result, digits, maximum);
}
break;
}
p++;
}
if (roundFlag != 0 && RyuUtils.RoundResult(result, start, roundFlag,
out int decimalIndex, info))
{
if (decimalIndex > 0)
{
result[decimalIndex++] = RyuUtils.ZERO;
result[decimalIndex] = info.NumberDecimalSeparator[0];
}
result.Append(RyuUtils.ZERO);
}
if (soft && precision > 0)
{
RyuUtils.SoftenResult(result, info);
}
}
else if (!soft)
{
RyuUtils.Append0(result, precision);
}
}