static int to_chars(floating_decimal_64 v, bool sign, Span <char> result)
{
// Step 5: Print the decimal representation.
int index = 0;
if (sign)
{
result[index++] = '-';
}
uint64_t output = v.mantissa;
int32_t olength = decimalLength17(output);
// Print the decimal digits.
// The following code is equivalent to:
// for (uint32_t i = 0; i < olength - 1; ++i) {
// const uint32_t c = output % 10; output /= 10;
// result[index + olength - i] = (char) ('0' + c);
// }
// result[index] = '0' + output % 10;
int32_t i = 0;
// We prefer 32-bit operations, even on 64-bit platforms.
// We have at most 17 digits, and uint32_t can store 9 digits.
// If output doesn't fit into uint32_t, we cut off 8 digits,
// so the rest will fit into uint32_t.
if ((output >> 32) != 0)
{
// Expensive 64-bit division.
uint64_t q = div1e8(output);
uint32_t output3 = ((uint32_t)output) - (100000000 * ((uint32_t)q));
output = q;
output3 = (uint)Math.DivRem((int)output3, 10000, out int32_t c);
int32_t d = (int32_t)(output3 % 10000);
int32_t c1 = Math.DivRem(c, 100, out int c0) << 1;
c0 <<= 1;
int32_t d1 = Math.DivRem(d, 100, out int d0) << 1;
d0 <<= 1;
DIGIT_TABLE.AsSpan(c0, 2).CopyTo(result.Slice(index + olength - i - 1));
DIGIT_TABLE.AsSpan(c1, 2).CopyTo(result.Slice(index + olength - i - 3));
DIGIT_TABLE.AsSpan(d0, 2).CopyTo(result.Slice(index + olength - i - 5));
DIGIT_TABLE.AsSpan(d1, 2).CopyTo(result.Slice(index + olength - i - 7));
i += 8;
}
uint32_t output2 = (uint32_t)output;
while (output2 >= 10000)
{
output2 = (uint32_t)Math.DivRem((int32_t)output2, 10000, out int32_t c);
int32_t c1 = Math.DivRem(c, 100, out int c0) << 1;
c0 <<= 1;
DIGIT_TABLE.AsSpan(c0, 2).CopyTo(result.Slice(index + olength - i - 1));
DIGIT_TABLE.AsSpan(c1, 2).CopyTo(result.Slice(index + olength - i - 3));
i += 4;
}
if (output2 >= 100)
{
output2 = (uint32_t)Math.DivRem((int32_t)output2, 100, out int32_t c);
c <<= 1;
DIGIT_TABLE.AsSpan(c, 2).CopyTo(result.Slice(index + olength - i - 1));
i += 2;
}
if (output2 >= 10)
{
uint32_t c = output2 << 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' + output2);
}
// Print decimal point if needed.
if (olength > 1)
{
result[index + 1] = '.';
index += olength + 1;
}
else
{
++index;
}
// Print the exponent.
result[index++] = 'E';
int32_t exp = v.exponent + olength - 1;
if (exp < 0)
{
result[index++] = '-';
exp = -exp;
}
if (exp >= 100)
{
DIGIT_TABLE.AsSpan(2 * Math.DivRem(exp, 10, out var c), 2).CopyTo(result.Slice(index));
result[index + 2] = (char)('0' + c);
index += 3;
}
else if (exp >= 10)
{
DIGIT_TABLE.AsSpan(2 * exp, 2).CopyTo(result.Slice(index));
index += 2;
}
else
{
result[index++] = (char)('0' + exp);
}
return(index);
}
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++] = '-';
}
int32_t output = (int)v.mantissa;
int32_t olength = decimalLength9((uint)output);
// Print the decimal digits.
// The following code is equivalent to:
// for (uint32_t i = 0; i < olength - 1; ++i) {
// const uint32_t c = output % 10; output /= 10;
// result[index + olength - i] = (char) ('0' + c);
// }
// result[index] = '0' + output % 10;
int32_t i = 0;
while (output >= 10000)
{
output = Math.DivRem(output, 10000, out int32_t c);
int32_t c1 = Math.DivRem(c, 100, out int32_t c0) << 1;
c0 <<= 1;
DIGIT_TABLE.AsSpan(c0, 2).CopyTo(result.Slice(index + olength - i - 1));
DIGIT_TABLE.AsSpan(c1, 2).CopyTo(result.Slice(index + olength - i - 3));
i += 4;
}
if (output >= 100)
{
output = Math.DivRem(output, 100, out int32_t c);
c <<= 1;
DIGIT_TABLE.AsSpan(c, 2).CopyTo(result.Slice(index + olength - i - 1));
i += 2;
}
if (output >= 10)
{
int32_t c = output << 1;
// We can't use memcpy here: the decimal dot goes between these two digits.
result[(int32_t)((uint32_t)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';
int32_t exp = v.exponent + olength - 1;
if (exp < 0)
{
result[index++] = '-';
exp = -exp;
}
if (exp >= 10)
{
DIGIT_TABLE.AsSpan(2 * exp, 2).CopyTo(result.Slice(index));
index += 2;
}
else
{
result[index++] = (char)('0' + exp);
}
return(index);
}
