gnupic: Thread: [PATCH] Bad warning for BRA on 16F code

I have found a warning that I believe is wrong. I am assembling for 16f1508 and I am 
getting a warning for a branch to a label with an odd address. Here is the test code:

> cat bad.asm
        LIST    P=PIC16F1518
        include p16f1518.inc

        org     0x000

        bra     main
;       nop
main:   goto    main

        end

> gpasm -c bad.asm ; gplink -o bad.hex bad.o
message: using default linker script 
"/usr/home/install/gputils/share/gputils/lkr/16f1518_g.lkr"
warning: destination address must be word aligned at 0 of section ".org_0"

If I add a nop instruction to make the destination even, there is no warning.

I understand that pic18 uses byte addressing, where 12f and 16f use word addresses, so 
pic18 destinations should always be even. With that in mind, I made this patch:

%diff -u libgputils/gpcofflink.c.orig libgputils/gpcofflink.c
--- libgputils/gpcofflink.c.orig        2013-07-10 22:00:41.000000000 -0600
+++ libgputils/gpcofflink.c     2013-07-21 21:42:21.000000000 -0600
@@ -1415,6 +1415,7 @@
     break;
 
   case RELOCT_BRA:
+    if (class != &proc_class_pic14e)
     if (value & 1) {
       gp_warning("destination address must be word aligned at %#x of section \"%s\"",
                  org, section->name);

I don't know if this patch is the right way to fix the error, but I hope it is useful.

Thanks!
-Richard

In Hex output, PIC always uses byte address. 
In assembly language, those trivial things happen all the time.


> From: ####@####.####
> To: ####@####.####
> Subject: [PATCH] Bad warning for BRA on 16F code
> Date: Sun, 21 Jul 2013 22:05:03 -0600
> 
> I have found a warning that I believe is wrong. I am assembling for 16f1508 and I am 
> getting a warning for a branch to a label with an odd address. Here is the test code:
> 
> > cat bad.asm
>         LIST    P=PIC16F1518
>         include p16f1518.inc
> 
>         org     0x000
> 
>         bra     main
> ;       nop
> main:   goto    main
> 
>         end
> 
> > gpasm -c bad.asm ; gplink -o bad.hex bad.o
> message: using default linker script 
> "/usr/home/install/gputils/share/gputils/lkr/16f1518_g.lkr"
> warning: destination address must be word aligned at 0 of section ".org_0"
> 
> If I add a nop instruction to make the destination even, there is no warning.
> 
> I understand that pic18 uses byte addressing, where 12f and 16f use word addresses, so 
> pic18 destinations should always be even. With that in mind, I made this patch:
> 
> %diff -u libgputils/gpcofflink.c.orig libgputils/gpcofflink.c
> --- libgputils/gpcofflink.c.orig        2013-07-10 22:00:41.000000000 -0600
> +++ libgputils/gpcofflink.c     2013-07-21 21:42:21.000000000 -0600
> @@ -1415,6 +1415,7 @@
>      break;
>  
>    case RELOCT_BRA:
> +    if (class != &proc_class_pic14e)
>      if (value & 1) {
>        gp_warning("destination address must be word aligned at %#x of section \"%s\"",
>                   org, section->name);
> 
> I don't know if this patch is the right way to fix the error, but I hope it is useful.
> 
> Thanks!
> -Richard
> 
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: ####@####.####
> For additional commands, e-mail: ####@####.####
> 
 		 	   		  

Not really, mid-range PICs have 14-bit word sizes and they use word
addressing, not byte addressing. In the other hand 18F (otherwise known as
high-performance) has 16bit program memory storage and can be addressed at
byte level, therefore the 16bit word alignment is required (but as far as I
know you cannot even load uneven addresses using BRA or GOTO, as with BRA
the address is encoded in a '2n' way so it is sifted left, and in GOTO the
bit 0 is ignored from the given address).

16f1518 is an enhanced-mid-range, it has 14bit size words, addresses
program memory by words, not bytes, and does not require alignments.

Tamas


On 22 July 2013 09:54, mengjin su ####@####.#### wrote:

> In Hex output, PIC always uses byte address.
> In assembly language, those trivial things happen all the time.
>
>
> > From: ####@####.####
> > To: ####@####.####
> > Subject: [PATCH] Bad warning for BRA on 16F code
> > Date: Sun, 21 Jul 2013 22:05:03 -0600
> >
> > I have found a warning that I believe is wrong. I am assembling for
> 16f1508 and I am
> > getting a warning for a branch to a label with an odd address. Here is
> the test code:
> >
> > > cat bad.asm
> >         LIST    P=PIC16F1518
> >         include p16f1518.inc
> >
> >         org     0x000
> >
> >         bra     main
> > ;       nop
> > main:   goto    main
> >
> >         end
> >
> > > gpasm -c bad.asm ; gplink -o bad.hex bad.o
> > message: using default linker script
> > "/usr/home/install/gputils/share/gputils/lkr/16f1518_g.lkr"
> > warning: destination address must be word aligned at 0 of section
> ".org_0"
> >
> > If I add a nop instruction to make the destination even, there is no
> warning.
> >
> > I understand that pic18 uses byte addressing, where 12f and 16f use word
> addresses, so
> > pic18 destinations should always be even. With that in mind, I made this
> patch:
> >
> > %diff -u libgputils/gpcofflink.c.orig libgputils/gpcofflink.c
> > --- libgputils/gpcofflink.c.orig        2013-07-10 22:00:41.000000000
> -0600
> > +++ libgputils/gpcofflink.c     2013-07-21 21:42:21.000000000 -0600
> > @@ -1415,6 +1415,7 @@
> >      break;
> >
> >    case RELOCT_BRA:
> > +    if (class != &proc_class_pic14e)
> >      if (value & 1) {
> >        gp_warning("destination address must be word aligned at %#x of
> section \"%s\"",
> >                   org, section->name);
> >
> > I don't know if this patch is the right way to fix the error, but I hope
> it is useful.
> >
> > Thanks!
> > -Richard
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: ####@####.####
> > For additional commands, e-mail: ####@####.####
> >
>
>



-- 
int main() { char *a,*s,*q; printf(s="int main() { char *a,*s,*q;
printf(s=%s%s%s, q=%s%s%s%s,s,q,q,a=%s%s%s%s,q,q,q,a,a,q); }",
q="\"",s,q,q,a="\\",q,q,q,a,a,q); }

Fixed in svn revision #984.

The gputils snapshot build source package is available at 
http://sourceforge.net/projects/gputils/files/snapshot_builds/src/gputils-src-20130724-984.tar.gz.
Windows 32bit setup package is at 
http://sourceforge.net/projects/gputils/files/snapshot_builds/i686-mingw32msvc/gputils-20130724-984-setup.exe.

Borut

On 22. 07. 2013 20:04, Tamas Rudnai wrote:
> Not really, mid-range PICs have 14-bit word sizes and they use word
> addressing, not byte addressing. In the other hand 18F (otherwise known as
> high-performance) has 16bit program memory storage and can be addressed at
> byte level, therefore the 16bit word alignment is required (but as far as I
> know you cannot even load uneven addresses using BRA or GOTO, as with BRA
> the address is encoded in a '2n' way so it is sifted left, and in GOTO the
> bit 0 is ignored from the given address).
>
> 16f1518 is an enhanced-mid-range, it has 14bit size words, addresses
> program memory by words, not bytes, and does not require alignments.
>
> Tamas
>
>
> On 22 July 2013 09:54, mengjin su ####@####.#### wrote:
>
>> In Hex output, PIC always uses byte address.
>> In assembly language, those trivial things happen all the time.
>>
>>
>>> From: ####@####.####
>>> To: ####@####.####
>>> Subject: [PATCH] Bad warning for BRA on 16F code
>>> Date: Sun, 21 Jul 2013 22:05:03 -0600
>>>
>>> I have found a warning that I believe is wrong. I am assembling for
>> 16f1508 and I am
>>> getting a warning for a branch to a label with an odd address. Here is
>> the test code:
>>>> cat bad.asm
>>>          LIST    P=PIC16F1518
>>>          include p16f1518.inc
>>>
>>>          org     0x000
>>>
>>>          bra     main
>>> ;       nop
>>> main:   goto    main
>>>
>>>          end
>>>
>>>> gpasm -c bad.asm ; gplink -o bad.hex bad.o
>>> message: using default linker script
>>> "/usr/home/install/gputils/share/gputils/lkr/16f1518_g.lkr"
>>> warning: destination address must be word aligned at 0 of section
>> ".org_0"
>>> If I add a nop instruction to make the destination even, there is no
>> warning.
>>> I understand that pic18 uses byte addressing, where 12f and 16f use word
>> addresses, so
>>> pic18 destinations should always be even. With that in mind, I made this
>> patch:
>>> %diff -u libgputils/gpcofflink.c.orig libgputils/gpcofflink.c
>>> --- libgputils/gpcofflink.c.orig        2013-07-10 22:00:41.000000000
>> -0600
>>> +++ libgputils/gpcofflink.c     2013-07-21 21:42:21.000000000 -0600
>>> @@ -1415,6 +1415,7 @@
>>>       break;
>>>
>>>     case RELOCT_BRA:
>>> +    if (class != &proc_class_pic14e)
>>>       if (value & 1) {
>>>         gp_warning("destination address must be word aligned at %#x of
>> section \"%s\"",
>>>                    org, section->name);
>>>
>>> I don't know if this patch is the right way to fix the error, but I hope
>> it is useful.
>>> Thanks!
>>> -Richard
>>>
>>> ---------------------------------------------------------------------
>>> To unsubscribe, e-mail: ####@####.####
>>> For additional commands, e-mail: ####@####.####
>>>
>>
>
>