Subj : [SpiderMonkey] JS_Get/SetPrivate truncates 0x1 bit
To   : netscape.public.mozilla.jseng
From : Brian Barnes
Date : Sat May 22 2004 02:54 am

Does JS_GetPrivate and JS_SetPrivate do something funny (other than 
convert to jsval) to the data you pass it?

I wanted to pass it just an integer (not an actual pointer to data, but 
mangle to a pointer), and it seems to strip off the 0x1 bit.

For instance:

int		i=5,k;
void		*v;

	// make sure cast works

v=(void*)i;
k=(int)v;
fprintf(stdout,"%d\n",k);

	// call set/get

JS_SetPrivate(cx,obj,(void*)i);
k=(int)JS_GetPrivate(cx,obj);
fprintf(stdout,"%d\n",k);

You'd get:

5
4

I don't know how the heck it knows the difference between my pointer 
and regular integers, unless I'm getting lucky and my pointers always 
have the 0x1 bit at 0 (could potentially be true.)

The workaround is to make a static array (like int 
intarray[]={0,1,2,3,4,5,6,7} but that's a little silly :) )

I know I'm missing something obvious here.

[>] Brian

.