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SMAUG
SMAUG coding
problems reading bit vectors
problems reading bit vectors

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Posted by
 Gdub
(32 posts) bio

Date
 Wed 01 May 2024 03:54 PM (UTC) Amended on Wed 01 May 2024 06:39 PM (UTC) by Gdub

Message
 I'm having trouble reading an extended bit vector. I'm trying to use the isflagged functionality from SMAUGFUSS ported into SMAUG 1.4a. Everything is compiling, being set and reading/saving from disc (as far as I can tell) but there's a strange conversion error when ifchecking and reading the flag.
setting flag:
mpflag noexpire $n justtesting 2
checking flag:
if isflagged($n,justtesting,2)
mpecho checking isflagged for $n  $n has a flag
else
mpe isflagged not working yet.
endif
vstat
Vnum: 3 Tag: justtesting Timer: 0
Type: XBIT Data: [1 1]
pfile
#VARIABLE
Type 2
Flags 0
Vnum 3
Ctime 1714581585
Mtime 1714581783
Rtime 0
Timer 0
Tag justtesting~
Xbit 6
End
when stepping through the code  specifically in the "isflagged" portion of mprog_do_ifcheck(). The flag is being read as '2' which what is the value being set in script but once it does the flag = abs(flag) % MAX_BITS; it is converted to '64' and then returns as false or unset.
flag = abs(flag) % MAX_BITS; // hrmm, Vooodoo
switch (vd>type)
{
case vtSTR:
case vtINT:
return FALSE;
case vtXBIT:
if (xIS_SET(*(EXT_BV*)vd>data, flag) == TRUE)
{
bFlag = TRUE;
}
else
{
bFlag = FALSE;
}
return bFlag;
}
defines:
#define xIS_SET(var, bit) ((var).bits[(bit) >> RSV] & 1 << ((bit) & XBM))
#define xSET_BIT(var, bit) ((var).bits[(bit) >> RSV] = 1 << ((bit) & XBM))
#ifndef INTBITS
#define INTBITS 32
#endif
#define XBM 31 /* extended bitmask ( INTBITS  1 ) */
#define RSV 5 /* rightshift value ( sqrt(XBM+1) ) */
#define XBI 4 /* integers in an extended bitvector */
#define MAX_BITS XBI * INTBITS
 top 

Posted by
 Nick Gammon
Australia (23,026 posts) bio
Forum Administrator 
Date
 Reply #1 on Wed 01 May 2024 07:54 PM (UTC) 
Message

if (xIS_SET(*(EXT_BV*)vd>data, flag) == TRUE)
That is just giving zero if not set and nonzero if set. Don't compare to TRUE. 
 Nick Gammon
www.gammon.com.au, www.mushclient.com  top 

Posted by
 Gdub
(32 posts) bio

Date
 Reply #2 on Wed 01 May 2024 09:52 PM (UTC) Amended on Thu 02 May 2024 02:24 AM (UTC) by Gdub

Message

Nick Gammon said:
if (xIS_SET(*(EXT_BV*)vd>data, flag) == TRUE)
That is just giving zero if not set and nonzero if set. Don't compare to TRUE.
thanks Nick! That didn't seem to change the results, but a good reminder for me...
Should I try any of the other bit macros?
bool ext_is_empty args( ( EXT_BV *bits ) );
void ext_clear_bits args( ( EXT_BV *bits ) );
int ext_has_bits args( ( EXT_BV *var, EXT_BV *bits) );
bool ext_same_bits args( ( EXT_BV *var, EXT_BV *bits) );
void ext_set_bits args( ( EXT_BV *var, EXT_BV *bits) );
void ext_remove_bits args( ( EXT_BV *var, EXT_BV *bits) );
void ext_toggle_bits args( ( EXT_BV *var, EXT_BV *bits) );
/*
* Here are the extended bitvector macros:
*/
#define xIS_SET(var, bit) ((var).bits[(bit) >> RSV] & 1 << ((bit) & XBM))
#define xSET_BIT(var, bit) ((var).bits[(bit) >> RSV] = 1 << ((bit) & XBM))
#define xSET_BITS(var, bit) (ext_set_bits(&(var), &(bit)))
#define xREMOVE_BIT(var, bit) ((var).bits[(bit) >> RSV] &= ~(1 << ((bit) & XBM)))
#define xREMOVE_BITS(var, bit) (ext_remove_bits(&(var), &(bit)))
#define xTOGGLE_BIT(var, bit) ((var).bits[(bit) >> RSV] ^= 1 << ((bit) & XBM))
#define xTOGGLE_BITS(var, bit) (ext_toggle_bits(&(var), &(bit)))
#define xCLEAR_BITS(var) (ext_clear_bits(&(var)))
#define xIS_EMPTY(var) (ext_is_empty(&(var)))
#define xHAS_BITS(var, bit) (ext_has_bits(&(var), &(bit)))
#define xSAME_BITS(var, bit) (ext_same_bits(&(var), &(bit)))
commenting this line out makes the flags read properly but I'm not sure what functionality I'm losing by doing this? is it just a guard from combining too many flags and going over the max?
flag = abs(flag) % MAX_BITS;
why would abs(2) % 128 resolve to 64? Shouldn't it be 2?  top 

Posted by
 Nick Gammon
Australia (23,026 posts) bio
Forum Administrator 
Date
 Reply #3 on Thu 02 May 2024 06:50 AM (UTC) 
Message
 What type does "flag" have?
Yes, 2 % 128 would be 2. I'm not sure why they are using abs there, unless a negative flag has some subtle meaning. 
 Nick Gammon
www.gammon.com.au, www.mushclient.com  top 

Posted by
 Gdub
(32 posts) bio

Date
 Reply #4 on Thu 02 May 2024 09:30 PM (UTC) Amended on Fri 03 May 2024 09:49 AM (UTC) by Nick Gammon

Message

this is how its being set
if (argc > 3)
flag = atoi(argv[3]);
I commented this out and now the entire system works. I am going to consider this resolved for the time being until I run into a bug with it.
flag = abs(flag) % MAX_BITS;
Thank you Nick, appreciate your help.  top 

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