Embedded Strings in your Code Space

[Darrel Taylor]

Hi Steve,

While I don't see any advantages over the previous examples, it does present a few problems that weren't there before.

They are the same problems I came across when writing the strings program I pointed out in the 2nd post of this thread.

By using the "dt" directive, it uses twice as much code space by only storing 1 byte per word. The "da" directive is much more efficient. It packs two 7-bit characters in each word.

Also, when using the MOVE?CW macro inside another macro, it makes it so that all string data has to be placed at the beginning of the program. If you place the string data after the SendString command that's trying to use it, you will get a "Address label duplicate or defferent in second pass" error.

John Barrat figured out how to get around that problem with this macro. It compiles to the exact same thing as the MOVE?CW, but because of which "Pass" it gets compiled on, it can find an address either before or after the code that uses it.

'------------GetAddress Macro - Location insensitive -------------------------
ASM
GetAddress macro Label, Wout       ; Returns the Address of a Label as a Word
    CHK?RP Wout
    movlw low Label
    movwf Wout
    movlw High Label
    movwf Wout + 1
    endm
ENDASM

I think, once you fix those 2 things, you'll have something that looks just like my Strings prog. See second post.
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I do like this though

    @ errorlevel 0,-207 ' avoid anoying MPASM error message 
                        ' -- found label after column 1 --

Sure makes things look better when you can indent labels.
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[mister_e]

Yep i understand it... the only thing... HOW TO use DA to send numeric Value, say 13,10 or else 8 bits value with the string???

I tried the \ option... doesn't seems to work as i want. well i can miss something really stupid/easy... once again.

BUT it works with dt. BUT i agree with you, i take 2 time the needed space.

[Darrel Taylor]

"DA" works fine with anything under 128, so 10,13 isn't a problem.

   da  "Danger Will Robinson",13,10,0

But you're right. Unless you are using an 18F part, if you want 8-bit data, it will take 2x the code space.

[mister_e]

mmm i already tried the above... MIIIIIIIIP doesn't work. GOT YA... for the first time in my life... probably the last too

We must send a 14 bit pack stuff... as it's suppose to!

So i just found that

@ da "This is a string....",0x068a,0

the above will send cr+lf.

Sounds like

CR con 13
LF con 10
CRLF var WORD

CRLF.HighByte=CR
CRLF=CRLF>>1
CRLF.LOWBYTE=CRLF.LowByte | LF

it works... just harder to figure out. BAH could be worst. And BTW, a 18F will be more appropriate for that.

About the String placement... you're right. As i figure to place all string at the top, it shouldn't be a problem. All the string together. Make it easy if some modification have to be done.

[mister_e]

mmm, another solution...

String1 da "My string",13,10,"blah blah",13,10,125,126,127,0

Just modify a little bit the StringOut Sub

StringOut:  ' Send the string out via Hserout
    Readcode Addr, TwoChars       ' Get the 14 bit packed characters
    Char = TwoChars >> 7          ' Separate first char
    if Char then                  ' Look for Null char, Stop if found
       hserout [Char]             ' Send first char
       endif

    Char = TwoChars & $7F         ' Separate second char
    if Char then                  ' Look for Null char, Stop if found
       hserout [Char]             ' Send the second char
       Addr = Addr + 1            ' Point to next two characters
       goto StringOut	          ' Continue with rest of the string
       endif
return

that way it works. BUT it don't take all the advantage of the 14 BIT pack stuff. It's just more readable the the previous.

[Darrel Taylor]

Hmmmpf,

Apparently, none of them are right.

With mine, it puts 00's in front of each byte (13,10), that will cause the send routine to terminate early.

With the 0x068a, if there's an ODD number of characters in the string, it will pad the string with a 00, again causing the send routine to terminate early.

So there doesn't seem to be a way to add CRLF on the end of a string with "DA".

Your program seems to have an advantage after all. My apologies.
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[Darrel Taylor]

How dare you fix my program while I'm still posting that you were right!

Ha ha, Good job!
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[mister_e]

OK as i will probably never happen again, i'll write the date/month/year in my notebook with the note

once in my life, i beat Mr Darrel Taylor
THE Canadian 1
United State 0

Just kidding Darrel I learn a lot from all of your previous posts.

Keep up the good work !!!

[Darrel Taylor]

Oh shoot,

Still has that "Padding the string" problem.

010D   26F9 1073 3A72 00255 String1 da "My string",13,10,"blah blah",13,10,125,126,127,0
       34EE 3380 000D
       000A 316C 30E8
       1062 3661 3400
       000D 000A 007D
       007E 007F 0000

Sendstring still terminates early if the string has an ODD number of charaters.

Almost there.

P.S.

THE Canadian 0.99

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