problem with detzcode on machines w/64 bit longs

J.T. Conklin jtc at
Fri Mar 10 05:41:30 UTC 1995

Chris Demetriou, who maintains the NetBSD DEC Alpha port, reported a
problem in localtime.c's detzcode() function that occurs because the
value being extracted from the string in that function is not sign 
extended properly.

He says: 
	The problem is that if you do what the current version does,
	then you can end up with numbers like 0xffffyyyy being
	returned from detzcode(), i.e. no sign extension into the
	upper 32 bits of the long.  Because of this, among other
	things, 'date' will say that it's some time in the year

Using the following detzcode() implementation (which unrolls the loop
and doesn't mask the first character) works, but it suffers from a 
small defect in that it assumes signed characters.

	static long
	const char * const      codep;
		register long   result;

		result = (codep[0] << 24) \
		       | (codep[1] & 0xff) << 16 \
		       | (codep[2] & 0xff) << 8
		       | (codep[3] & 0xff);
		return result;

casting codep[0] to signed char would fix that, but would require a
ANSI compiler.


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