> -----Original Message-----
> From:
.....piclist-bouncesKILLspam
.....mit.edu
> [
EraseMEpiclist-bouncesspam_OUTTakeThisOuTmit.edu]On Behalf
> Of Ken Pergola
> Sent: 08 October 2004 17:46
> To: Microcontroller discussion list - Public.
> Subject: RE: [PIC]Splitting assemblies in to multiple files
>
>
>
> Some clarifications:
>
>
> Ken Pergola was wrong in writing:
>
> > Please note that you cannot use the 'ORG' directive in
> > code targeted for the linker.
>
>
> I should have said that you most likely will never need to use the ORG
> directive in code targeted for the linker.
>
> The ORG directive will compile in code targeted for the
> linker, and although
> I personally never use the 'ORG' directive in my linker-based
> code, it is
> legal:
>
>
> >From MPLAB IDE's online help:
>
> =====
> When generating an object file, the org directive is interpreted as
> introducing an absolute CODE section with an internally
> generated name. For
> example:
>
> L1: org 0x200
> is interpreted as:
>
> .scnname CODE 0x200
> L1:
> where .scnname is generated by the assembler, and will be
> distinct from
> every name previously generated in this context.
> ====
>
>
>
> Jan-Erik wrote:
>
> > code_reset code h'0000'
> > goto main
> >
> > code_isr code '0008'
> > your ISR code
> >
> > then later (anyware actualy) :
> >
> > code_main code ; no address needed.
> >
> > main do-whatever...
> >
> > Note that "code_isr" and "code_main" are not labels, they
> > are names of the code sections in the source.
>
>
> Just to add what Jan-Erik said, the text name or label
> *before* the CODE
> directive does not *have* to be a reference to a SECTION NAME
> defined in the
> linker script file. I feel it is very important to know this.
>
>
> 1) You can use a SECTION NAME if you need that functionality
> and need to
> place code in that code section referenced by the section
> name in the linker
> script, or, you can just use a label so that in the MAP file
> you will see
> this label as a meaningful name under the 'Section' heading.
>
> 2) If that label is not a section name defined in your linker
> script file,
> MPLINK will place the code anywhere it sees fit.
>
> 3) You also have the choice of NOT putting a label in front
> of the CODE
> directive -- if you do this, MPLINK generates a name for you
> in the MAP file
> for that particular code section.
>
>
>
> For example, I don't even like to supply absolute addresses
> in my reset and
> ISR source code when I use the linker (I prefer to keep all
> this in the
> linker file to reduce editing absolute addresses in my source file):
>
>
>
> ResetVector CODE
> .
> .
> .
>
> Main_code CODE
> .
> .
> .
>
> InterruptVector_HighPri CODE
> .
> .
> .
>
> InterruptVector_LowPri CODE
>
> .
> .
> .
>
>
>
>
> 'Main_code', 'InterruptVector_HighPri' and
> 'InterruptVector_HighPri' are a
> SECTION NAMEs that I defined in the linker script file.
>
>
> CODEPAGE NAME=ResetVector START=0x000000 END=0x000007
> CODEPAGE NAME=IntVectorHiPri START=0x000008 END=0x000017
> CODEPAGE NAME=IntVectorLoPri START=0x000018 END=0x000027
> CODEPAGE NAME=ApplicationCode1 START=0x000028 END=0x0065FF
>
>
> SECTION NAME=Main_code ROM=ApplicationCode1
> SECTION NAME=ResetVector ROM=ResetVector
> SECTION NAME=InterruptVector_HighPri ROM=IntVectorHiPri
> SECTION NAME=InterruptVector_LowPri ROM=IntVectorLoPri
>
>
>
> Note that all labels before the CODE directive above are
> actually the names
> SECTIONs in the linker script. However, I do have some code
> sections in
> which I do not want to reference a specific SECTION in the
> linker script --
> I want the linker to automatically allocate it, but I also
> want to see a
> meaningful name for that code section in the MAP file:
>
>
> In those instances I just do this:
>
>
> Messaging_code CODE
>
>
> 'Messaging_code' is just a label of my choosing and it is NOT
> a SECTION name
> in this case -- it appears in the MAP file like this:
> (hopefully the formatting below does not get mangled)
>
>
> Section Info
> Section Type Address Location Size(Bytes)
> --------- --------- --------- --------- ---------
> ResetVector code 0x000000 program 0x000008
> InterruptVector_HighPri code 0x000008 program 0x000002
> InterruptVector_LowPri code 0x000018 program 0x000002
> Main_code code 0x000028 program 0x0000b4
> Messaging_code code 0x003f76 program 0x00007e
>
>
> If I decided not put that 'Messaging_code' label in front of the CODE
> directive and just use the 'CODE' directive by itself, the
> MAP file listing
> would be different:
>
> Section Info
> Section Type Address Location Size(Bytes)
> --------- --------- --------- --------- ---------
> ResetVector code 0x000000 program 0x000008
> InterruptVector_HighPri code 0x000008 program 0x000002
> externalLatch_code code 0x00000a program 0x00000e
> InterruptVector_LowPri code 0x000018 program 0x000002
> .code code 0x003f76 program 0x00007e
>
>
>
> See how using 'Messaging_code CODE' in your source code creates a
> meaningful section name in the MAP file? 'Messaging_code'
> versus '.code'
> (which MPLINK generated).
>
>
> I hope this is helpful.
>
> Best regards,
>
> Ken Pergola
>
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> Best regards,
>
> Ken Pergola
>
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