I'm jumping in mid thread here, 'cos I only just got around to subscribing (Hi Marko, hi Steve, and anyone who still remembers Christopher Jam), so thump me if I'm re-covering old ground ;-) I remember this for one nybble: ; input: a in 0..15 ; output: petscii hex representation of a ; 0..9 -> $30..$39 ; A..F -> $41..$46 cmp#$0a bcc $1 adc#$06 .$1 adc#$30 ; (7*10+6*8)/16 = 7.375 cycles so we can fairly naively extrapolate to the following: ; input: a contains num ; output: x,a contain the ascii hex representation of num tay lsr a lsr a lsr a lsr a cmp#$0a bcc $1 adc#$06 .$1 adc#$30 tax tya and#$30 cmp#$0a bcc $2 adc#$06 .$2 adc#$30 ; 10+7.375+6+7.375 = 30.75 cycles ... plus how ever many cycles you need to load/store the values. This should be beatable, cos I haven't really put that much thought into it, but I should get back to work now :-) Christopher. > -----Original Message----- > From: Professor Dredd [mailto:email@example.com] > Sent: 17 March 2001 11:01 > To: firstname.lastname@example.org > Subject: Re: Assy question - I challenge you to do better! > > > I know I didn't disqualify table use in my challenge > so I suppose thats the fastest possible way, eh Steve? > ;-) > > Indeed the cycle count is as low as possible! > Howevever, your 2-table3 algo uses just over 2 pages > of memory! :-O > > If I were going to use tables, I might be more > inclined to do something like: > > LDA BYTE > LSR > LSR > LSR > LSR > TAX > LDA TABLE,X > STA $FB > LDA BYTE > AND #$0F > TAX > LDA TABLE,X > STA $FC > RTS > TABEL TXT '0123456789ABCDEF' > > I THINK that should do it, (Spiro?) > > Does anyone know a NON-TABLE algo to do the same thing > with lowest possible cycle count? > --- Steve Judd <email@example.com> wrote: > > On Fri, 16 Mar 2001, Professor Dredd wrote: > > > > > For some time I've wondered if there were a faster > > way > > > to convert binary to ASCII coded hex. I even > > played > > > with some BCD numbers before I understood the > > Decimal > > > mode. If you can code an algorithm with the lowest > > > possible cycle count to process in 1-byte chunks, > > > please do :-) > > > > LDX num > > LDA highnyb,X > > LDY lownyb,X > > > > -S > > > > - > > This message was sent through the cbm-hackers > > mailing list. > > To unsubscribe: echo unsubscribe | mail > firstname.lastname@example.org. > > > ===== > Get a FREE 6Mb webmail box from go6502! - > http://www.geocities.com/profdredd > > As low as 2.99% Intro APR from NextCard! - > http://www.nextcard.com/index6.html?ref=aff0074521 > > PayPal is the FAST FREE and SECURE way to send money! - > https://secure.paypal.x.com/refer/pal=profdredd%40yahoo.com > > __________________________________________________ > Do You Yahoo!? > Get email at your own domain with Yahoo! Mail. > http://personal.mail.yahoo.com/ > - > This message was sent through the cbm-hackers mailing list. > To unsubscribe: echo unsubscribe | mail > email@example.com. > -Virus scanned and cleared ok - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail firstname.lastname@example.org.
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