transfer a string from ROM to an array

[Marcick]

Hi all,
I'm using this code to load an array with a certain text string

inbuff VAR BYTE(100)  
arraywrite inbuff,["Sample test string"]

I have many different string in variuos parts of the program and this code consumes a lot of space, so I would like to optimize it using macros .

It's easy to store the string in code space and then with a macro retrieve the address and read it:

ROM_String1:       PokeCode "Sample test string",0


; macro to retrieve the address

@getaddr	macro Text, Addr
@ 	movlw low Text
@ 	movwf Addr
@ 	movlw High Text
@ 	movwf Addr + 1
@ endm


; code
	@ getaddr _ROM_String1, _w0
  repeat
    peekcode w0, x
    if x then 
      debug x
      w0=w0+2
    endif
  until x=0                                     ' print till end of string '0'

Sb00:
	.....

Now I have some difficulties to continue: instead of print the string, I need to store it in RAM, the same things that does ArrayWrite.
So the macro should be modified to accept as parameters, the source ROM string and the destination address in RAM
Something like

@ LoadStr _ROM_CfgString, _inbuff

So calling the macro I can specify any string stored in ROM and any RAM destination where to put it.
Could anybody help me to complete the macro ?
Thanks
Marco

[HenrikOlsson]

Hi,
How about:

inBuff VAR BYTE[100]
i VAR BYTE

i = 24         ' Start putting the string at inBuff[24] for example  
repeat
  peekcode w0, x
  if x then 
    inBuff[i] = x
    debug x
    w0=w0+2
  endif
  i=i+1
until x=0

/Henrik.

[Marcick]

Hi Enrik, thanks,
inbuff should be a parameter passed to the macro and not a fixed address.

I have something like this:

inBuff VAR BYTE[100]
Outbuff VAR BYTE[100]
Testbuff VAR BYTE[200]
etc etc

I want that Inbuff, Outbuff, TestBuff is a parameter of the macro, so the string can be written anywhere

[HenrikOlsson]

I'm not very good at assembly language but can't you just pass it the variable name, like _inBuff, which would be the "start adress" of the array?

/Henrik.

[Marcick]

There must be some awful mistakes, I can't get this code working

#CONFIG
	CONFIG	OSC = IRCIO67	    ;Internal oscillator block, port function on RA6 and RA7
	CONFIG	WDT = ON	    	;WDT enabled
	CONFIG	WDTPS = 64	    	;1:64
	CONFIG	PWRT = ON	    	;PWRT enabled
	CONFIG	BOREN = BOHW	    ;Brown-out Reset enabled in hardware only (SBOREN is disabled)
	CONFIG	BORV = 3	    	;VBOR set to 2.1V
	CONFIG	MCLRE = OFF	    	;RE3 input pin enabled; MCLR disabled
	CONFIG	LPT1OSC = OFF	    ;Timer1 configured for higher power operation
	CONFIG	PBADEN = OFF	    ;PORTB<4:0> pins are configured as digital I/O on Reset
	CONFIG	XINST = OFF	    	;Instruction set extension and Indexed Addressing mode disabled (Legacy mode)
	CONFIG	LVP = OFF	    	;Single-Supply ICSP disabled
	CONFIG	STVREN = ON
	CONFIG	CP0 = ON
	CONFIG	CP1 = ON
	CONFIG	CP2 = ON
	CONFIG	CP3 = ON
#ENDCONFIG

	Define 		USE_LFSR 	1
	DEFINE		OSC			8
	DEFINE		DEBUG_REG	PORTB
	DEFINE		DEBUG_BIT	4
	DEFINE		DEBUG_BAUD	9600
	DEFINE		DEBUG_MODE	0		
	
	OSCCON		=%01110000			
	Led			VAR PORTB.3
	inbuff		VAR BYTE[100]
	x			VAR BYTE
	y			VAR BYTE
	LS0 		VAR Word
	LS1 		VAR Word

	goto	Start

ASM
LoadString	 macro Text, Dest
 	movlw low Text
	movwf _LS0
 	movlw High Text
 	movwf _LS0 + 1
	movlw low Dest
	movwf _LS1
	movlw High Dest
	movwf _LS1 + 1
 	L?CALL   _Lstr
 endm
ENDASM

Lstr:
	y=0
  	repeat
    	peekcode LS0, x
		LS1(y)=x
		y=y+1
	    LS0=LS0+2
    until x=0                                     
  return


Start:
	@ LoadString _ROM_CfgString, inbuff
	debug str inbuff\100,13,10
	pause 500
	high led
	pause 500
	low led
	goto start

end

ROM_CfgString:       PokeCode "This a test string",0

[richard]

try a forum search "embedded string"

[Marcick]

What I can't find how to do, is to pass to the macro the address of an array.

[richard]

as henrik said
inBuff VAR BYTE[100]


in asm the array address is
_inBuff

or give a new name

ASM
mybuff =_inBuff
ENDASM
note label in col 0

make sure you don't overrun your buffer

[Marcick]

Hi, I undestand, but I can't put togheter something of working. If you want to have a look to this code, you'll see in my comments where are my doubts.
Anyway the code doesn't compile and give errors ...

	inbuff		VAR BYTE[100]
	x			VAR BYTE
	y			VAR BYTE
	LS0 		VAR WORD
	LS1			VAR WORD

Lp1:
	@ LoadInbuff _ROM_CfgString, _Inbuff		; I would like to transfer the ROM string in RAM Inbuff
	debug str inbuff\100,13,10
	goto lp1

ASM
LoadInbuff	 macro Text, Dest
	CHK?RP _LS0
 	movlw low Text		; here I load in LS0 the ROM address of the source string
	movwf _LS0
 	movlw High Text
 	movwf _LS0 + 1
	CHK?RP _LS1			; here I suppose to load in LS1 the address of the destination buffer
 	movlw low Dest		; but I feel something is wrong
	movwf _LS1
 	movlw High Dest
 	movwf _LS1 + 1
	L?CALL   _Lstr
 endm
ENDASM

Lstr:
	y=0
  	do
    	peekcode LS0, x
		; --->>> what to do here to write the value x to the destination buffer ??
		if x=0 then exit
		y=y+1
	    LS0=LS0+2
    loop
  return



ROM_CfgString:       PokeCode "This a test string",0

[richard]

add this to your code
ARRAYWRITE inbuff,3,,["123"]

and then look at the lst file generated

see how arraywrite works

01487 LIST
000004 C00C FFE9 01488 ARRAYWRITE movff R5, FSR0L ; Put the array pointer into FSR0
000008 C00D FFEA 01489 movff R5 + 1, FSR0H
00000C 6EEE 01490 movwf POSTINC0 ; Put the char into the array and bump up the address
00000E CFE9 F00C 01491 movff FSR0L, R5 ; Save new pointer
000012 CFEA F00D 01492 movff FSR0H, R5 + 1

the array address goes in like this

C:\PBP3\EXAMPLES\MARCICK.PBP 00074 ARRAYWRITE inbuff,3,,["123"]
00192 ARRAYWRITENAME?B _inbuff
M MOVE?CW _inbuff, R5
M ifdef USE_LINKER
M CHK?RP R5
M movlw low (_inbuff)
M movwf R5
M movlw high (_inbuff)
M movwf (R5) + 1

you need to emulate this using your own vars don't use r5 of course


interrupts will need to be disabled too


ps the forum totally destroys white space you need to look at your xxx.lst file to make it out properly

[Marcick]

Richard,
Thanks for your time but .. if you have some more ... could you please take my sample above and correct it so it works ?
It's two days I'm turning crazy.
Anyway thank you
Marco

[richard]

'pic18f45k20
'****************************************************************
'*  Name    : UNTITLED.BAS                                      *
'*  Author  : [select VIEW...EDITOR OPTIONS]                    *
'*  Notice  : Copyright (c) 2015 [select VIEW...EDITOR OPTIONS] *
'*          : All Rights Reserved                               *
'*  Date    : 4/14/2015                                         *
'*  Version : 1.0                                               *
'*  Notes   :                                                   *
'*          :                                                   *
'****************************************************************
'*  Name    : UNTITLED.BAS                                      *
'*  Author  : [select VIEW...EDITOR OPTIONS]                    *
'*  Notice  : Copyright (c) 2015 [select VIEW...EDITOR OPTIONS] *
'*          : All Rights Reserved                               *
'*  Date    : 4/14/2015                                         *
'*  Version : 1.0                                               *
'*  Notes   :                                                   *
'*          :                                                   *
'****************************************************************
 #CONFIG
  CONFIG  FOSC = INTIO67
  CONFIG  FCMEN = OFF
  CONFIG  IESO = OFF
  CONFIG  PWRT = OFF
  CONFIG  BOREN = SBORDIS
  CONFIG  BORV = 18
  CONFIG  WDTEN = ON
  CONFIG  WDTPS = 512
  CONFIG  CCP2MX = PORTC
  CONFIG  PBADEN = OFF
  CONFIG  LPT1OSC = OFF
  CONFIG  HFOFST = ON
  CONFIG  MCLRE = ON
  CONFIG  STVREN = ON
  CONFIG  LVP = OFF
  CONFIG  XINST = OFF
  CONFIG  DEBUG = OFF
  CONFIG  CP0 = OFF
  CONFIG  CP1 = OFF
  CONFIG  CP2 = OFF
  CONFIG  CP3 = OFF
  CONFIG  CPB = OFF
  CONFIG  CPD = OFF
  CONFIG  WRT0 = OFF
  CONFIG  WRT1 = OFF
  CONFIG  WRT2 = OFF
  CONFIG  WRT3 = OFF
  CONFIG  WRTC = OFF
  CONFIG  WRTB = OFF
  CONFIG  WRTD = OFF
  CONFIG  EBTR0 = OFF
  CONFIG  EBTR1 = OFF
  CONFIG  EBTR2 = OFF
  CONFIG  EBTR3 = OFF
  CONFIG  EBTRB = OFF
#ENDCONFIG


  define OSC 64
 osccon=$70   '64 mhz
 OSCTUNE.6=1
 
 
 
 pause 2000
 
Serout2 PORTb.7,84,["ready",13,10] 
 
Addr var word
 Char var byte
 cnt var byte
inbuff  var byte[30]
buff var byte[30]
 Clear

 



 goto StartLoop ' Required

 String1:
 @ da "This is a string",0

 AnotherString:
 @ da "Here is another string",0

 '------------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


 StartLoop: ' This loop repeats continuously just as a test.
@ GetAddress _String1, _Addr ' Get address of String
 cnt=0
 gosub StringOut ' Send the String
 Serout2 PORTb.7,84, [13,10] ' New Line
 Serout2 PORTb.7,84, ["inbuff ",str inbuff\cnt ,13,10] ' New Line


@ GetAddress _AnotherString, _Addr ' Get address of String
 cnt=0
 gosub StringOut ' Send the String
 Serout2 PORTb.7,84,[13,10] ' New Line
 Serout2 PORTb.7,84, ["inbuff ",str inbuff\cnt ,13,10] ' New Line
 pause 500
 goto StartLoop ' Repeat


 StringOut: ' Send the string out via Hserout
 Readcode Addr, Char ' Get a character
 if Char = 0 then StringDone ' Look for Null char, Stop if found
 buff[cnt]=char
 cnt=cnt+1
 Serout2 PORTb.7,84, [Char] ' Send char
 Addr = Addr + 1 ' Point to next character
 goto StringOut ' Continue with rest of the string
 StringDone:
 ARRAYWRITE inbuff,cnt,,[str buff]
 return


 end

I do it this way , and use the bounds checking features of arraywrite

[Marcick]

Well, any help is appreciated, so thank you anyway, but this is not what I'm asking.
My intent is not to use Arraywrite because consumes a lot of space.
With this sample code that now works I transfer a ROM string to an array, but I want also the destination array to be a parameter passed to the macro.
So with a single macro I could transfer to inbuff or testbuff or any buffer Is declared.

	Define 		USE_LFSR 	1
	DEFINE		OSC			8
	DEFINE		DEBUG_REG	PORTB
	DEFINE		DEBUG_BIT	4
	DEFINE		DEBUG_BAUD	9600
	DEFINE		DEBUG_MODE	0	
	
	OSCCON		=%01110000	

	inbuff		VAR BYTE[100]
	x			VAR BYTE
	y			VAR BYTE
	LS0 		VAR WORD
	LS1			VAR WORD
	goto Lp1

ASM
LoadInbuff	 macro Text
	CHK?RP _LS0
 	movlw low Text		; here I load in LS0 the ROM address of the source string
	movwf _LS0
 	movlw High Text
 	movwf _LS0 + 1
	L?CALL   _Lstr
 endm
ENDASM

Lstr:
	y=0
  	do
	    	peekcode LS0, x
		inbuff(y)=x
		if x=0 then exit
		y=y+1
		LS0=LS0+2
	loop
	return


Lp1:
	@ LoadInbuff _ROM_CfgString
	debug str inbuff\100,13,10
	goto lp1


ROM_CfgString:       PokeCode "This a test string",0

[richard]

I understand but pbp does not allow pointers like in C . the only way I can see for this to be done is to have either a user cmd or asm code that actually mimics arraywrite's array loading method anyway .I'm sure something like that could be made accept a pointer to the array to be loaded .
I'm just having trouble seeing any point to this. my prog with arraywite 1041 bytes , with arraywrite commented out 951 bytes ,surely 90 bytes is pretty good I'm sure my asm attempts would be much worse than that
I have to ask why do this at all . I can't see a good reason to read a string from flash into ram ,surely its best shuffled off to its destination directly . if it needs to be altered before its used was it really a good move putting it in flash memory in the first place.
have a look at this thread post#50 where I update portions of an array with EXT modifiers and arraywrite . the fixed unchanging parts could be in flash
http://www.picbasic.co.uk/forum/showthread.php?t=19420
perhaps if you provide a little more detail .....

[Marcick]

Hi Richard,
yes, strings need to be altered before use.
Well, I had about 3K free on 64k (PIC18F4680) and needed to add more code, so I was looking for some tricks to save space and make a diet to the actual code.
I have noted that if I substitute an arraywrite entry (for a string of about 100 char) with the method above, I save around 600 bytes of code. I have about 10 difefrent strings, so the total saved space is several KB.
To be honest I can't understand why there is so much difference between the two methods ....
Also I have noted this: in a blank project like the sample above, the difference between the two methods is about 150 bytes. Inside my 63KB project, the difference is more than 600 bytes.
So it probably depends where the instruction and the buffer are located (bank switching, etc). For thei sreason I wonder also if the method above with the macro is correct or can bring to unexpected behavours in some situations .....
For example: why did you say before "interrupts need to be disabled" ? Context is fully saved and restored in the interrupt routines. Also I use "PBP Instant Interrupt" of that great Darrel that should be bullet-proof.
Marco

[richard]

why did you say before "interrupts need to be disabled

I was thinking that if were to read the flash using TABLPU reg and index through the ram array using fsr0 then I'm not convinced that method is interrupt proof
but your not doing that anyway


I expect you realise that pokecode uses twice the memory to store a string compared to da

[Marcick]

well, I was not understanding why I had to increment the pointer by two when reading data ...
I have subsituted now pokecode with da and peekcode with readcode and saved another kb .. thanks !
Marco

[richard]

this might do what you want
note with the da method char values must be<128 ie 7 bit ascii
just noticed I left an arraywrite in there it can/should be removed and the bit setting the 0 at end of the string was fixed too

'****************************************************************
'*  Name    : UNTITLED.BAS                                      *
'*  Author  : [select VIEW...EDITOR OPTIONS]                    *
'*  Notice  : Copyright (c) 2015 [select VIEW...EDITOR OPTIONS] *
'*          : All Rights Reserved                               *
'*  Date    : 4/14/2015                                         *
'*  Version : 1.0                                               *
'*  Notes   :                                                   *
'*          :                                                   *
'****************************************************************
'*  Name    : UNTITLED.BAS                                      *
'*  Author  : [select VIEW...EDITOR OPTIONS]                    *
'*  Notice  : Copyright (c) 2015 [select VIEW...EDITOR OPTIONS] *
'*          : All Rights Reserved                               *
'*  Date    : 4/14/2015                                         *
'*  Version : 1.0                                               *
'*  Notes   :                                                   *
'*          :                                                   *
'****************************************************************
 #CONFIG
  CONFIG  FOSC = INTIO67
  CONFIG  FCMEN = OFF
  CONFIG  IESO = OFF
  CONFIG  PWRT = OFF
  CONFIG  BOREN = SBORDIS
  CONFIG  BORV = 18
  CONFIG  WDTEN = ON
  CONFIG  WDTPS = 512
  CONFIG  CCP2MX = PORTC
  CONFIG  PBADEN = OFF
  CONFIG  LPT1OSC = OFF
  CONFIG  HFOFST = ON
  CONFIG  MCLRE = ON
  CONFIG  STVREN = ON
  CONFIG  LVP = OFF
  CONFIG  XINST = OFF
  CONFIG  DEBUG = OFF
  CONFIG  CP0 = OFF
  CONFIG  CP1 = OFF
  CONFIG  CP2 = OFF
  CONFIG  CP3 = OFF
  CONFIG  CPB = OFF
  CONFIG  CPD = OFF
  CONFIG  WRT0 = OFF
  CONFIG  WRT1 = OFF
  CONFIG  WRT2 = OFF
  CONFIG  WRT3 = OFF
  CONFIG  WRTC = OFF
  CONFIG  WRTB = OFF
  CONFIG  WRTD = OFF
  CONFIG  EBTR0 = OFF
  CONFIG  EBTR1 = OFF
  CONFIG  EBTR2 = OFF
  CONFIG  EBTR3 = OFF
  CONFIG  EBTRB = OFF
#ENDCONFIG


  define OSC 64
 osccon=$70   '64 mhz
 OSCTUNE.6=1
 
 
 
 pause 2000
 
Serout2 PORTb.7,84,["ready",13,10] 

Addr var word
 Char var byte
 cnt var word
inbuff  var byte[30]
buff var byte[30]
 Clear

 



 goto StartLoop ' Required

 String1:
 @ da "This is a string",0

 AnotherString:
 @ da "Here is another string",0
 
 '------------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
 
 ASM
Loadb	 macro buffer
	CHK?RP _cnt
 	movlw low buffer		
	movwf FSR2L
 	movlw High buffer
 	movwf FSR2H

 endm
ENDASM

 
 
 
 
 ARRAYWRITE buff,["123"]

 StartLoop: ' This loop repeats continuously just as a test.
@ GetAddress _String1, _Addr ' Get address of String
@ Loadb    _inbuff 
CNT=0
 
 gosub StringOut ' Send the String
 
 Serout2 PORTb.7,84, ["inbuff "," c ",hex CNT," ",str inbuff\CNT ,13,10] ' New Line



@ GetAddress _AnotherString, _Addr ' Get address of String
@ Loadb    _inbuff 
CNT=0

 gosub StringOut ' Send the String
 
 Serout2 PORTb.7,84, ["inbuff "," c ",hex CNT," ",str inbuff\CNT ,13,10] ' New Line
 pause 500
 goto StartLoop ' Repeat


 StringOut: ' Send the string out via Hserout
 Readcode Addr, Char ' Get a character
 if Char = 0 then StringDone ' Look for Null char, Stop if found
 bfill:
 asm
 	CHK?RP _Char
 	movf _Char ,w
    
    movwf  POSTINC2
   
 endasm
 
 
 
 cnt=cnt+1
 Addr = Addr + 1 ' Point to next character
 goto StringOut ' Continue with rest of the string
 
 
 StringDone:
 asm
 	
 	movlw 0
    
    movwf   INDF2
  endasm   
 return

 




 end

[Marcick]

Wow, thanks !
Need a break now. I'll let you know tomorrow or monday, as I test everything.
Marco

[richard]

a cleaned up version

[richard]

an even better way

[Marcick]

Hi again,
thanks for the cleaned and full working sample.
I'm much scared about "its not interrupt proof , other pbp functons may and do use FSR2 and TBLPTR" ....
I'll try to ask Melabs if it's safe or not.
Marco

[richard]

marco
I will give you three options
1. intcon.7=0 ' I'm assuming it was set
@ Flash2Ram _buff,_String1' Get a String from flash memory
intcon.7=1
2 . examine your .lst file and determine if any of your isr routines use FSR2 or TBLPTR
if none of them do then don't worry (this is the most likely case)
3. there are two other indirect addressing pointers FSR0 and FSR1 maybe one of them would be free

as groucho would say if you don't like these I have others

this is the best I can offer without seeing your code

[HenrikOlsson]

Hi,
Looking at the DT-INTS_18 file Darrel is declaring variables for saving the FSR's:

fsave0H     var WORD  BANK0  SYSTEM   ' locations for FSR registers
fsave1H     var WORD  BANK0  SYSTEM
fsave2H     var WORD  BANK0  SYSTEM
fsave0L     var WORD  BANK0  SYSTEM   ' low priority FSR locations
fsave1L     var WORD  BANK0  SYSTEM
fsave2L     var WORD  BANK0  SYSTEM

There's also a section towards the end that says

; ---[See if we need to save TBLPTR]------------------------------------------

Which sets a flag SAVE_TBLPTR = 1 when any PBP command that uses TBLPTR is used and in the ReEnterPBP-18 file he's declaring variables for TBLPTR like:

    TBLPTRU_H     VAR HP_Vars[31]
      TBLPTRU_SaveH VAR TBLPTRU_H.lowbyte
    TBLPTR_H      VAR HP_Vars[32]
      TBLPTRH_SaveH VAR TBLPTR_H.highbyte
      TBLPTRL_SaveH VAR TBLPTR_H.lowbyte

And then, further down in that file:

@ if Save_TBLPTR == 1
    TBLPTRU_SaveH = TBLPTRU
    TBLPTRH_SaveH = TBLPTRH
    TBLPTRL_SaveH = TBLPTRL
@ endif

So, to me, it looks like DT-INTS is handling all that stuff and you would/should only need to worry about it of you're using the FSR's or TBLPTR in any other ASM routines which would mean that DT-INTS does't detect them being used and therefor doesn't save them.

Of course I may have it all wrong in which case I hope someone who can understand the ASM in DT-Ints better then me can explain what's going on.

/Henrik.

[richard]

thanks for that henrik I never thought to look at how dt ints works . dt's code leaves nothing to chance ,I'm left humbled again

[Marcick]

Guys,
about Darrel code I could put my hand on fire.
about my code I can bet there are bugs ...
but with your help now I have everything clear and know where problems can be or not. I have DTint and other ISR where I'll take care about FSR and TBLPTR.
so, many thanks again for your support !
bye
Marco

[Marcick]

Hi Richard,
maybe I'm doing some confusion and about to say something of funny, but I have a doubt:
How do you ensure in this code that you are in the correct bank reading the address of "buffer" ?

ASM
Flash2Ram macro buffer, msg ; Fills the buffer from flash msg
   movlw   UPPER msg
   movwf   TBLPTRU
   movlw   HIGH msg
   movwf   TBLPTRH
   movlw   LOW msg
   movwf   TBLPTRL
   movlw   low buffer		
   movwf   FSR2L
   movlw   High buffer
   movwf   FSR2H
   L?CALL  _bfill
   endm
ENDASM

[richard]

buffer does not actually exist its just a label in the macro , when assembled
@ Flash2Ram _buff , _String1 , produces

000168 0E00               M    movlw   UPPER _String1
0016A 6EF8                 M    movwf   TBLPTRU
00016C 0E01               M    movlw   HIGH _String1
00016A 6EF8               M    movwf   TBLPTRU
00016C 0E01               M    movlw   HIGH _String1
00016E 6EF7               M    movwf   TBLPTRH
000170 0E3E               M    movlw   LOW _String1
000172 6EF6               M    movwf   TBLPTRL
000174 0E1A               M    movlw   low _buff            
000176 6ED9               M    movwf   FSR2L
000178 0E00               M    movlw   High _buff
00017A 6EDA               M    movwf   FSR2H
                          M    L?CALL  _bfill

the label "buffer" is replaced with the symbol of the intended target
at no stage do we actually write directly to the "buffer" we simply load its address (from the symbol table) into the fsr regs
the bfill subroutine then fills the "buffer" indirectly via the fsr regs
macro's are not subroutines they are just another shortcut way to save typing, every time the macro is encountered the real code as above is inserted into your program

[Marcick]

Yes, but while _String1 is a fixed address that point to a univoque ROM location, isn't _buff a RAM location that points to different register according to the current bank ?
Marco

[richard]

evidently I'm not explaining it well
we never write directly to _buff we do it 'indirectly' via the 16 bit full address in fsr2 its called INDIRECT ADDRESSING read the chapter in the data sheet ,(this is how pic18's have arrays that can be bigger than a ram bank)
bank select is not applicable to indirect addressing

[richard]

observe symbol table

inbuff  var byte[30]
 buff var byte[30]       $500

SYMBOL TABLE
LABEL VALUE

_STVREN_OFF_4L 000000FE
_STVREN_ON_4L 000000FF
_StartLoop 00000168
_String1 0000013E
_String2 00000150
_TRISH 00000F94
_TRISL 00000F93
_WDTEN_OFF_2H 000000FE
_WDTEN_ON_2H 000000FF
_WDTPS_1024_2H 000000F5
_WDTPS_128_2H 000000EF
_WDTPS_16384_2H 000000FD
_WDTPS_16_2H 000000E9
_WDTPS_1_2H 000000E1
_WDTPS_2048_2H 000000F7
_WDTPS_256_2H 000000F1
_WDTPS_2_2H 000000E3
_WDTPS_32768_2H 000000FF
_WDTPS_32_2H 000000EB
_WDTPS_4096_2H 000000F9
_WDTPS_4_2H 000000E5
_WDTPS_512_2H 000000F3
_WDTPS_64_2H 000000ED
_WDTPS_8192_2H 000000FB
_WDTPS_8_2H 000000E7
_WRT0_OFF_6L 000000FF
_WRT0_ON_6L 000000FE
_WRT1_OFF_6L 000000FF
_WRT1_ON_6L 000000FD
_WRT2_OFF_6L 000000FF
_WRT2_ON_6L 000000FB
_WRT3_OFF_6L 000000FF
_WRT3_ON_6L 000000F7
_WRTB_OFF_6H 000000FF
_WRTB_ON_6H 000000BF
_WRTC_OFF_6H 000000FF
_WRTC_ON_6H 000000DF
_WRTD_OFF_6H 000000FF
_WRTD_ON_6H 0000007F
_XINST_OFF_4L 000000BF
_XINST_ON_4L 000000FF
__18F45K20 00000001
_bfill 0000022C
_buff 00000500
_inbuff 0000001A
main 000000EA
pauseloop 000000A6
pauseusloop 000000C2
ser2delay 0000007C
serout2bit 0000004E
serout2done 0000004A
serout2loop 00000022
serout2norm 00000068

[richard]

buff var byte[30] $4f0 ; buff is now straddles banks 4 and 5

_buff 000004F0 symbol table

code still works perfectly as expected

[Marcick]

Richard,
the source of my doubts is that I have some unexpected behaviours and I'm trying to understand where is the problem.
Watching the program memory, I found some "00" chars here and there in the middle of the string
Lets' say the string "Hello",0 when I look the program memory is 48 65 6C 00 6C 6F 00
I'm discovering now that the directive "da" is only for PIC12/16 and not for PIC18

http://ww1.microchip.com/downloads/e...Doc/33014J.pdf

I think I should use "db" or "data", I'm trying to understand

"db" seems to work fine

[richard]

how are you looking at the pgm memory , I think something is not right

for me the da and data directives produce exactly the same result , I left the da directive in, thinking I might try the code on a pic16f1825 for a learning experience , for 7 bit ascii data either will do (pic 18's can store 2x8 bit ,pic 16's 2x7bit )

the relevant listings

0
0013E 6854 7369 6920 00199  data "This is a string",0
          2073 2061 7473 
          6972 676E 0000

00013E 6854 7369 6920 00199  da "This is a string",0
            2073 2061 7473 
            6972 676E 0000

[HenrikOlsson]

I think it might have something to do with the number of bytes (odd or even) in the string.
In both of Richards examples there's an even number of bytes (16 and 22) but your Hello string there's an odd number of bytes (5). I seem to remember an issue with this being discussed in one of the 'Strings in codespace' threads some years ago.

/Henrik.

[richard]

odd length strings , wastes space but not a problem


00013E 6854 7369 6920 00199 data "This is a string1",0
2073 2061 7473
6972 676E 0031
0000

00013E 6854 7369 6920 00199 da "This is a string1",0
2073 2061 7473
6972 676E 0031
0000

[richard]

00013E 6548 6C6C 006F 00199 da "Hello",0
0000

[richard]

there's another little cheat if all the strings are odd length the 0 terminator is redundant

[Marcick]

Found the problem.

I have a string like this:

say "hello"

I use this format do declare it, the same format I was using with arraywrite

@ da "say",34,"hello",34,0

The result in program memory is that before each char 34 is added a char 00
If I use "db" instead the result is correct.
The pdf I linked before says that "da" is not for PIC18

[richard]

where ?
da – Data ASCII.
Generates a packed 14-bit number representing two 7-bit ASCII characters.