Message String Table using Readcode

I've tested the following code on the PIC18F series (I don't know if it will work on other PIC's).

Code:

MsgBaseAddr var word MsgIdx var byte Msg_Ctr var byte Char_Ctr var byte ascii var byte '================================================ ' Program Start '================================================ 'GetMesg Program Routine retrieves character string from Message Table 'Format: "MsgIdx = X: GoSub GetMesg" (where X = 0 to last message in table) GetMesg: 'Initialize counters Msg_Ctr = 0 Char_Ctr = 0 'Retrieve Message Table Base Address asm movlw Low Msg_table movff WREG, _MsgBaseAddr movlw High Msg_table movff WREG, _MsgBaseAddr + 1 endasm 'Locate beginning of message string and adjust base address to match While MsgIdx > Msg_Ctr ' When we have a match, exit! Readcode MsgBaseAddr, ascii ' Retrieve character and MsgBaseAddr = MsgBaseAddr + 1 ' move index to next position. If ascii = 0 Then ' If at end-of-message... Msg_Ctr = Msg_Ctr + 1 ' Increment to next mesg string and If MsgBaseAddr // 2 = 0 Then ' Determine end-of-string padding. MsgBaseAddr = MsgBaseAddr + 2 ' If Even #, pad 2 spaces Else MsgBaseAddr = MsgBaseAddr + 1 ' If Odd #, pad 1 space Endif Endif Wend ;Retrieve message and send it GetString: Readcode (MsgBaseAddr + Char_Ctr), ascii ' Retrieve character If ascii = 0 Then Return ' Leave if end-of-message! '---- your output code goes here (HSEROUT [ascii], LCDOUT ascii, ect) ---- Char_Ctr = Char_Ctr + 1 ' set pointer to next character Goto GetString '================================================ ' Message Table '================================================ ' Each string is terminated with a 0 asm Msg_table DATA "message #0",0 DATA "message #1",0 DATA "message #2",0 DATA "message #3",0 DATA "message #4",0 DATA "message #5",0 DATA "message #6",0 DATA "message #7",0 DATA "message #8",0 DATA "message #9",0 DATA "message #10",0 endasm

Here is the format to call the above routine, in order to output the individual message strings:

Code:

MsgIdx = 0: GoSub GetMesg MsgIdx = 1: GoSub GetMesg MsgIdx = 2: GoSub GetMesg

In the section: "---- your output code goes here"
You can do whatever you desire to fullfill your particular needs. For instance; In the following example, we add a carriage return and linefeed at the end of the message string, sending it all out the hardware usart (RS232).

Code:

;Retrieve message and send it GetString: Readcode (MsgBaseAddr + Char_Ctr), ascii ' Retrieve character If ascii = 0 Then Exit ' Leave if end-of-message! HSEROUT [ascii] Char_Ctr = Char_Ctr + 1 ' set pointer to next character Goto GetString Exit: HSEROUT [$0D,$0A] Return

Anything is possible, just use your imagination.

Edit: corrected missing variable declaration for ascii

Enjoy,

Michael,

apart from the fact that you have missed to declare ascii VAR BYTE

it works just fine on my 18F's

That way I can probably get rid of an external EEPROM I was using for message strings.
(presuming there is codespace left to store the strings)

MANY THANKS!

I'll do some further testing and let you know the results.

Oppps!

Thanks Ralph,

Quote:

apart from the fact that you have missed to declare ascii VAR BYTE

I fixed it.

Quote:

That way I can probably get rid of an external EEPROM I was using for message strings.
(presuming there is codespace left to store the strings)

Depending on how you were doing this before, you might see a tremendous savings (especially true if you were using PBP's Table Lookup function).

I certainly can't take all the credit for the idea, since much of this was made possible by looking at other people's code examples. However I do think my approach is possibly unique, since I have been looking, and looking for a solution like this for quite some time now, and never found anything exactly like it. I would be curious to know what other PICs this will work on, since all I use now-a-days are the 18F series, and have no easy way to confirm this.