public bool sign; // negative sign exists
public static BigNumberBuffer Create()
{
BigNumberBuffer number = new BigNumberBuffer();
number.digits = new StringBuilder();
return(number);
}
private unsafe static Boolean NumberToBigInteger(ref BigNumberBuffer number, ref BigInteger value)
{
Int32 i = number.scale;
Int32 cur = 0;
value = 0;
while (--i >= 0)
{
value *= 10;
if (number.digits[cur] != '\0')
{
value += (Int32)(number.digits[cur++] - '0');
}
}
while (number.digits[cur] != '\0')
{
if (number.digits[cur++] != '0')
{
return(false); // disallow non-zero trailing decimal places
}
}
if (number.sign)
{
value = -value;
}
return(true);
}
private unsafe static Boolean HexNumberToBigInteger(ref BigNumberBuffer number, ref BigInteger value)
{
if (number.digits == null || number.digits.Length == 0)
{
return(false);
}
int len = number.digits.Length - 1; // ignore trailing '\0'
byte[] bits = new byte[(len / 2) + (len % 2)];
bool shift = false;
bool isNegative = false;
int bitIndex = 0;
// parse the string into a little-endian two's complement byte array
// string value : O F E B 7 \0
// string index (i) : 0 1 2 3 4 5 <--
// byte[] (bitIndex): 2 1 1 0 0 <--
//
for (int i = len - 1; i > -1; i--)
{
char c = number.digits[i];
byte b;
if (c >= '0' && c <= '9')
{
b = (byte)(c - '0');
}
else if (c >= 'A' && c <= 'F')
{
b = (byte)((c - 'A') + 10);
}
else
{
b = (byte)((c - 'a') + 10);
}
if (i == 0 && (b & 0x08) == 0x08)
{
isNegative = true;
}
if (shift)
{
bits[bitIndex] = (byte)(bits[bitIndex] | (b << 4));
bitIndex++;
}
else
{
bits[bitIndex] = isNegative ? (byte)(b | 0xF0) : (b);
}
shift = !shift;
}
value = new BigInteger(bits);
return(true);
}
internal unsafe static Boolean TryParseBigInteger(String value, NumberStyles style, NumberFormatInfo info, out BigInteger result)
{
result = BigInteger.Zero;
ArgumentException e;
if (!TryValidateParseStyleInteger(style, out e))
{
throw e; // TryParse still throws ArgumentException on invalid NumberStyles
}
BigNumberBuffer bignumber = BigNumberBuffer.Create();
Byte * numberBufferBytes = stackalloc Byte[NumberPort.NumberBuffer.NumberBufferBytes];
NumberPort.NumberBuffer number = new NumberPort.NumberBuffer(numberBufferBytes);
result = 0;
if (!NumberPort.TryStringToNumber(value, style, ref number, bignumber.digits, info, false))
{
return(false);
}
bignumber.precision = number.precision;
bignumber.scale = number.scale;
bignumber.sign = number.sign;
if ((style & NumberStyles.AllowHexSpecifier) != 0)
{
if (!HexNumberToBigInteger(ref bignumber, ref result))
{
return(false);
}
}
else
{
if (!NumberToBigInteger(ref bignumber, ref result))
{
return(false);
}
}
return(true);
}
