Don't have an account? Register now to chat, post, use our tools, and much more.
Online Users
There are 106 users online: 7 members, 75 guests and 24 bots.
Members: adriweb, critor, geekboy1011, roblabla, ssquirtle7777, tifreak8x, zeldaking.
Bots: Spinn3r (2), Magpie Crawler (3), Googlebot (18), MSN/Bing (1).
SAX
This is an archived, read-only copy of the United-TI subforum , including posts and topic from May 2003 to April 2012. If you would like to discuss any of the topics in this forum, you can visit Cemetech's z80 Assembly subforum. Some of these topics may also be directly-linked to active Cemetech topics. If you are a Cemetech member with a linked United-TI account, you can link United-TI topics here with your current Cemetech topics.

Z80 & 68k Assembly => z80 Assembly
Author Message

Joined: 18 Sep 2010
Posts: 74

 Posted: 06 Oct 2010 05:22:21 pm    Post subject: Hello, I have a quick question... For my parser, I want to change decimal numbers written in ASCII code to pure hex code. I know this is possible, as Axe and the OS do this quite frequently. How exactly do I do this quickly and memory efficiently?
calc84maniac

Elite

Joined: 22 Jan 2007
Posts: 770

 Posted: 06 Oct 2010 08:24:00 pm    Post subject: Here is a z80 routine I whipped up, which will read ASCII digits pointed to by DE into a binary number in HL, stopping when a non-digit character is reached. Code: ``` ;Start with 0   ld hl,0 digitLoop: ;Read character and make sure it is a digit   ld a,(de)   sub '0'   cp 10   jr nc,notADigit ;Increment pointer   inc de ;Multiply HL by 10   ld b,h   ld c,l   add hl,hl   add hl,hl   add hl,bc   add hl,hl ;Add the digit value in A to HL   add a,l   ld l,a   jr nc,digitLoop   inc h   jr digitLoop notADigit:``` Edit: Made it actually stop where the non-digit was found instead of the character afterward.Last edited by Guest on 06 Oct 2010 08:25:12 pm; edited 1 time in total

Joined: 18 Sep 2010
Posts: 74

Posted: 07 Oct 2010 04:21:12 am    Post subject:

 calc84maniac wrote: Here is a z80 routine I whipped up, which will read ASCII digits pointed to by DE into a binary number in HL, stopping when a non-digit character is reached. Code: ``` ;Start with 0   ld hl,0 digitLoop: ;Read character and make sure it is a digit   ld a,(de)   sub '0'   cp 10   jr nc,notADigit ;Increment pointer   inc de ;Multiply HL by 10   ld b,h   ld c,l   add hl,hl   add hl,hl   add hl,bc   add hl,hl ;Add the digit value in A to HL   add a,l   ld l,a   jr nc,digitLoop   inc h   jr digitLoop notADigit:``` Edit: Made it actually stop where the non-digit was found instead of the character afterward.

Joined: 18 Sep 2010
Posts: 74

 Posted: 07 Oct 2010 12:41:44 pm    Post subject: Oh, and I just improved it some while fooling around with Mimas during my history class. But of course, this is only a minor addition so that it only reads five digits of a number (next addition will to make it only accept numbers less than 65353). Code: ``` ;Start with 0   db DD   ld l,5   ld hl,0 digitLoop: ;push the a register and then compare to IXL   dec ix   push af    ld a,0   db DD   cp l   jr z,notADigit    pop af ;Read character and make sure it is a digit   ld a,(de)   sub '0'   cp 10   jr nc,notADigit ;Increment pointer   inc de ;Multiply HL by 10   ld b,h   ld c,l   add hl,hl   add hl,hl   add hl,bc   add hl,hl ;Add the digit value in A to HL   add a,l   ld l,a   jr nc,digitLoop   inc h   jr digitLoop notADigit:   ret ```
 Display posts from previous: All Posts Oldest FirstNewest First
Register to Join the Conversation
Have your own thoughts to add to this or any other topic? Want to ask a question, offer a suggestion, share your own programs and projects, upload a file to the file archives, get help with calculator and computer programming, or simply chat with like-minded coders and tech and calculator enthusiasts via the site-wide AJAX SAX widget? Registration for a free Cemetech account only takes a minute.

»
 Page 1 of 1 » All times are GMT - 5 Hours

© Copyright 2000-2013 Cemetech & Kerm Martian :: Page Execution Time: 0.025770 seconds.