Incrementing time represented as NBCD format Blitz Posting Freak Posts: 788 Threads: 53 Joined: Nov 2002 12-05-2006, 08:23 PM NBCD stands for Natural Binary Coded Decimal and basically means that you store decimal numbers as you naturally would on paper, except as binary. So what does this mean? It means you use 4 bits to store one number, 0-9. And store them as the ordinary decimal positioning system. So the hexdecimal number 0x3459 stands for the decimal number 3459 and not what it actually means in binary (which is 13401). In this case we're storing time as minutes and seconds in the NBCD format. For example, 0x4712 means 47 minutes and 12 seconds. So the challenge is to write the most elegant code (in which ever language prefer) you can to increment an integer representing time (only minutes and seconds). You have to makes sure that 0x5959 wraps back to 0 once incremented. Challenge closes in exactly one week. Good luck oship me and i will give you lots of guurrls and beeea 1000101 Senior Member Posts: 451 Threads: 16 Joined: Feb 2003 12-06-2006, 12:28 AM FreeBasic code (tested with Win32 CVS Dec 5, 2006) Code:```#Define HexPad( Number, Padding )   ( Right( String( Padding, "0" ) & Hex( Number ), Padding ) ) Type sTime Field = 1       As uByte   Seconds, Minutes    End Type Sub Inc( Byval pByte As uByte Ptr )       *pByte += 1    If ( ( *pByte And &H0F ) = &H0A ) Then *pByte += ( &H10 - &H0A )    End Sub Sub IncTime( Byval pTime As sTime Ptr )       Inc( @pTime->Seconds )    If ( pTime->Seconds = &H60 ) Then       pTime->Seconds = &H00       Inc( @pTime->Minutes )       If ( pTime->Minutes = &H60 ) Then pTime->Minutes = &H00    End If    End Sub Sub DisplayTime( Byval pTime As sTime Ptr )       Dim As uByte   Seconds = ( ( pTime->Seconds Shr 4 ) * 10 ) + ( pTime->Seconds And &H0F )    Dim As uByte   Minutes = ( ( pTime->Minutes Shr 4 ) * 10 ) + ( pTime->Minutes And &H0F )       Print Using "##:##   0x"; Minutes; Seconds;    Print HexPad( *cPtr( uShort Ptr, pTime ), 4 )    End Sub Dim As sTime   Clock DisplayTime( @Clock ) For X As Integer = 1 to 60 * 60       IncTime( @Clock )    DisplayTime( @Clock )    Next Sleep End``` Life is like a box of chocolates', hrm, WTF, no it isn't, more like, 'life is like a steaming pile of horse crap.' yetifoot Senior Member Posts: 484 Threads: 14 Joined: Apr 2005 12-06-2006, 02:30 AM Thats a pretty nice solution by 1000101 there, I would have done it a similar way, but in order to have something to show, I decided to do it the following way. Again FreeBASIC, Code:```Function inc_nbcd_timestamp(ByVal timestamp As Integer) As Integer   timestamp += 1   timestamp += Abs((timestamp AND &H000F) = &H000A) * &H0006   timestamp += Abs((timestamp AND &H00F0) = &H0060) * &H00A0   timestamp += Abs((timestamp AND &H0F00) = &H0A00) * &H0600   timestamp += Abs((timestamp AND &HF000) = &H6000) * &HA000   timestamp AND= &HFFFF      Function = timestamp      End Function ' JUST SOME TESTING OUTPUT Dim ts As Integer Cls ts = &H5805 For i As Integer = 0 To (60 * 2)   Locate 1, 1   ts = inc_nbcd_timestamp(ts)   Print "0x" + Hex(ts, 4)   Sleep 150 Next i``` EVEN MEN OF STEEL RUST. Blitz Posting Freak Posts: 788 Threads: 53 Joined: Nov 2002 12-06-2006, 03:18 AM Here's my best shot Code:```function nbcdTimeIncr ( byval t as integer ) as integer     t1 = t + &ha6a7     m1 = t  and &h11110     m2 = t1 and &h11110          nbcdTimeIncr =  t1 - ((((not (m1 xor m2)) and &h11110) shr 4)*&hf and &ha6a6) end function``` Add AND &hffff if you care that the upper 16 bits are zero or not. oship me and i will give you lots of guurrls and beeea yetifoot Senior Member Posts: 484 Threads: 14 Joined: Apr 2005 12-06-2006, 08:34 AM Very interesting, I'm still trying to understand exactly how it works, but I think I'm getting there. I managed to spot a couple of reductions: Code:```function inc_nbcd_timestamp ( byval t as integer ) as integer   dim as integer t1        t1 = t + &HA6A7            function =  t1 - (((((t EQV t1) AND &H11110) shr 4) * &HF) AND &HA6A6)      end function``` EVEN MEN OF STEEL RUST. LooseCaboose Senior Member Posts: 691 Threads: 5 Joined: Apr 2002 12-06-2006, 12:31 PM Its easy in Ada: Code:```procedure add is   type time is mod 60;   secs : time := 0;   mins : time := 0; begin   secs := secs + 1;   if secs = 0 then     mins := mins + 1;   end if; end add;``` esus saves.... Passes to Moses, shoots, he scores! Dio Senior Member Posts: 650 Threads: 26 Joined: Aug 2004 12-06-2006, 01:03 PM i think i misunderstood. Code:`? mid\$(time\$,4,2)+right\$(time\$,2):sleep` quote="whitetiger0990"]whitetiger is.. WHITE POWER!!! [/quote] Here Blitz Posting Freak Posts: 788 Threads: 53 Joined: Nov 2002 12-06-2006, 05:02 PM Loose, that's nice. Though that's not really in the nbcd format is it? Dio, i think you missunderstood. It's not a matter of getting the time as a string. yetifoot, ic. Didn't know eqv was defined as exactly that. I didn't actually write it in FB. It was originally in assembler. It works by incrementing the number by one, then adding the correct bits so that the numbers which has gone past past 9 and 6 overflow to the next number and wrap around. oship me and i will give you lots of guurrls and beeea yetifoot Senior Member Posts: 484 Threads: 14 Joined: Apr 2005 12-07-2006, 01:22 AM I had a play around in assembler too, i thought the BCD functions might be useful, DAA in particular, using some carry trickery. I was hoping to get a code in only 4 or 5 instructions, but the best I could do was 11 including the moves to/from timestamp, and that wasn't using the x86 BCD instructions at all, it was just a quick reworking based on your code, EVEN MEN OF STEEL RUST. LooseCaboose Senior Member Posts: 691 Threads: 5 Joined: Apr 2002 12-07-2006, 01:39 AM Quote:Loose, that's nice. Though that's not really in the nbcd format is it? Depends on the Ada compiler I guess ;-). I could create a record subtype that has both the minutes and seconds inside, but there is no guarantee the compiler would allocate 16 contiguous bits for it (it probably wouldn't). Ada is quite nice for somethings, but utterly horrid for others. I played around with a bit shifty solution, but yours is pretty tough to beat ;-). esus saves.... Passes to Moses, shoots, he scores! « Next Oldest | Next Newest »