gnupic: Re: gpasm directives vs. MPASM
Subject:
Re: gpasm directives vs. MPASM
From:
Molnár ####@####.####
Date:
3 Dec 2015 19:08:52 -0000
Message-Id: <20151203200849.59baedebec67bf40599f7c6b@freemail.hu>
On Thu, 3 Dec 2015 11:03:52 -0600
Jerry Zdenek ####@####.#### wrote:
> Where does it say that it is a hardware limitation?
>
> It's just convention to store a 16bit value as 4 4bit values. You could
> equally store it as 2 8bit values.
>
> Jerry
You are right, because the number of the usable bits is differs and not clearly written that it is a hardware limit. I remembered badly.
Example 4-bit: In the http://ww1.microchip.com/downloads/en/DeviceDoc/41640A.pdf page 3, "2.3.1 USER ID LOCATIONS" section.
Example 4-bit: In the http://ww1.microchip.com/downloads/en/DeviceDoc/41227E.pdf page 2, "2.2 User ID Locations" section.
Example 7-bit: In the http://ww1.microchip.com/downloads/en/DeviceDoc/41244F.pdf page 6, "2.2 User ID Locations" section.
Example 7-bit: In the http://ww1.microchip.com/downloads/en/DeviceDoc/40001713A.pdf page 5, "3.1 User ID Location" section.
Example 7-bit: In the http://ww1.microchip.com/downloads/en/DeviceDoc/40001796A.pdf page 6, "3.1 User ID Location" section.
It seems 4 bits are available upon the 12-bit devices and 7 bits are available upon the 14-bit devices.
Károly
>
> On 12/3/2015 2:25 AM, Molnár Károly wrote:
> > 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
> >
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> >
>
>
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