Re: SXHASH isn't process-independent (bug)

[Taiichi Yuasa <yuasa%tutics.tut.junet%utokyo-relay.csnet@RELAY.CS.NET>]

    From: Jeff Dalton
    Subject: SXHASH isn't process-independent (bug)
    Date: Tue, 8 Dec 87

    SXHASH, According to Steele, page 285, must have the following property:
    ...
    However, KCL SXHASHes symbols simply by casting them to integers (taking
    their address as a fixnum).  Hence it is not invocation-independent.
    For example,
    ...
    SXHASH should change, but the hash for EQ hash tables, used now by SXHASH,
    should not change since it doesn't need to have this property.

There was a bug in the definition of the C function hash_eql
in file c/hash.d.  To fix the bug, replace the first lines of the definition

    int
    hash_eql(x)
    object x;
    {
    	int h;
    
    	switch (type_of(x)) {
    	case t_fixnum:
    		return(fix(x));
    ...
    }

with

    int
    hash_eql(x)
    object x;
    {
=>	int h = 0, i;
    	char *s;

    	switch (type_of(x)) {
=>	case t_symbol:
=>		for (i = x->s.s_fillp, s = x->s.s_self;  i > 0;  --i, s++)
=>			h += (*s & 0377)*12345 + 1;
=>		return(h);

    	case t_fixnum:
    		return(fix(x));
    ...
    }

-- Taiichi