Function fxSourceMapValue

xs/sources/xsSourceMap.c:185–211

#define VLQ_MASK_BITS (VLQ_CONTINUATION_BIT - 1)

txInteger fxSourceMapValue(txParser* parser, txString* p)
{
	txInteger continuation, digit = 0, result = 0, shift = 0;
	txString q = *p;
	do {
		char c = *q++;
		if (('A' <= c) && (c <= 'Z'))
			digit = c - 'A';
		else if (('a' <= c) && (c <= 'z'))
			digit = c - 'a' + 26;
		else if (('0' <= c) && (c <= '9'))
			digit = c - '0' + 52;
		else if (c == '+')
			digit = 62;
		else if (c == '/')
			digit = 63;
		else
			fxReportParserError(parser, parser->states[0].line, "source map: unexpected character"); 
		continuation = digit & VLQ_CONTINUATION_BIT;
		digit &= VLQ_MASK_BITS;
		result += (digit << shift);
		shift += VLQ_SHIFT;
	} while (continuation);
	*p = q;
	shift = result >> 1;
	return ((result & 1) == 1) ? -shift : shift;
}