gnupic: Re: gpasm directives vs. MPASM
Subject:
Re: gpasm directives vs. MPASM
From:
Molnár ####@####.####
Date:
3 Dec 2015 08:25:22 -0000
Message-Id: <20151203092520.4ee93d397c634674b9080960@freemail.hu>
On Mon, 30 Nov 2015 15:22:26 -0500
"Andrew E. Mileski" ####@####.#### wrote:
>
> First, thanks to all those involved for the marvelous gputils suite!
>
> I admit to being a PIC rookie, but it seems that gpasm is parsing the IDLOCS
> symbol as a directive, even when the --mpasm-compatible option is used, despite
> IDLOCS not being a MPASM directive (as far as I can tell).
>
> Is this a potential bug / "feature"? Or is there a command-line option or
> something else that I'm overlooking which avoids this behaviour?
>
> I don't rule out that I could be doing something really stupid.
>
> IDLOCS appears to be a standard section name; grep the linker files. An example
> of the following can be found in the current MPASM manual (DS33014L), page 28.
> I've just condensed the code, and set the processor type for this example.
>
> LIST p=16f1829
>
> IDLOCS CODE
>
> dw H'048C'
> dw H'159D'
> dw H'26AE'
> dw H'37BF'
>
> END
>
> $ ./gpasm --mpasm-compatible -c bug.asm
> bug.asm:4:Warning[205] Found directive in column 1: "IDLOCS"
> bug.asm:4:Error[181] Directive Error: The IDLOCS directive is invalid in MPASM
> mode.
>
> I would expect IDLOCS to be treated like any other section label when
> --mpasm-compatible is specified.
>
> I was considering patching the ^{IDENT}:? pattern in scan.l to return LABEL
> instead of IDENTIFIER for gpasm-specific directives in the ID_DIRECTIVES case
> when --mpasm-compatible is specified... unless there is a better route?
>
> ~~
> Andrew E. Mileski
>
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>
The gpasm works a little differently. Citations from the gputils handbook:
CHAPTER 2. GPASM 18
__IDLOCS __IDLOCS <expression> or __IDLOCS <expression1>,<expression2>
Sets the PIC processor’s identification locations. For 12 and 14 bit processors, the four id locations
are set to the hexadecimal value of expression. For 18cxx devices idlocation expression1 is set to
the hexadecimal value of expression2.
.
.
.
.
.
CHAPTER 2. GPASM 22
IDLOCS <expression> or IDLOCS <expression1>,<expression2>
In “gpasm” mode (if the command line is not included the "--mpasm-compatible" option), in the case
of PIC18FXXX processors it is possible to use this directive.
The expressions may be are as follows: string (“abcdef”), character (’a’), constant (0x37), symbol (NUM1)
These may be used simultaneously: IDLOCS “abcd”, 0x76, ’D’, NUM1
The length of IDLOCS can be at most 8 bytes.
--------------------------------------------------------------------------
So in your case so that should be used:
LIST p=16f1829
__IDLOCS H'048C'
END
The compiler will do this:
0x8000: 0x0C
0x8001: 0x08
0x8002: 0x04
0x8003: 0x00
That is, a single 16-bit value stored in four 4-bit part. This is a hardware limitation.
Therefore the __IDLOCS directive can be used only once in the 12-bit and 14-bit devices.
See: http://ww1.microchip.com/downloads/en/DeviceDoc/40001440E.pdf, page 51
Molnár Károly
