Function CVT_get_numeric

src/jrd/cvt.cpp:184–329

UCHAR CVT_get_numeric(const UCHAR* string, const USHORT length, SSHORT* scale, void* ptr)
{
/**************************************
 *
 *      C V T _ g e t _ n u m e r i c
 *
 **************************************
 *
 * Functional description
 *      Convert a numeric literal (string) to its binary value.
 *
 *	According to the literal passed (contains an exponent or not,
 *      what datatype fits) returns long, int64, int128, double or decfloat.
 *
 *      The return value from the function is set to dtype_decfloat, dtype_double,
 *      dtype_int128, dtype_int64 or dtype_long depending on the conversion performed.
 *      The binary value is stored at the address given by ptr.
 *
 **************************************/
	dsc desc;

	MOVE_CLEAR(&desc, sizeof(desc));
	desc.dsc_dtype = dtype_text;
	desc.dsc_ttype() = ttype_ascii;
	desc.dsc_length = length;
	desc.dsc_address = const_cast<UCHAR*>(string);
	// The above line allows the assignment, but "string" is treated as const
	// for all the purposes here.

	SINT64 value = 0;
	SSHORT local_scale = 0, sign = 0;
	bool digit_seen = false, fraction = false, over = false;

	const UCHAR* p = string;
	if (length > 2 && p[0] == '0' && p[1] == 'X')
	{
		*(Int128*) ptr = CVT_hex_to_int128(reinterpret_cast<const char*>(p + 2), length - 2);
		*scale = 0;
		return dtype_int128;
	}

	const UCHAR* const end = p + length;
	for (; p < end; p++)
	{
		if (DIGIT(*p))
		{
			digit_seen = true;

			// Before computing the next value, make sure there will be
			// no overflow. Trying to detect overflow after the fact is
			// tricky: the value doesn't always become negative after an
			// overflow!

			if (!over)
			{
				if (static_cast<FB_UINT64>(value) >= NUMERIC_LIMIT)
				{
					// possibility of an overflow