gnupic: Re: sdcc feature request: some help needed (partial solution patch)
Subject:
re: sdcc feature request: some help needed (partial solution patch)
From:
Peter ####@####.####
Date:
1 May 2005 22:42:08 +0100
Message-Id: <pgosx.giog@itpf.ibaa.uj.jvcmi>
Hi, this is in continuation to my feature request. I have studied the
code and arrived at some conclusions on where the changes are to be made
and how, but I would appreciate a 'guiding hand'. Please see below for
details.
>---------- Forwarded message ----------
>Date: Fri, 29 Apr 2005 23:22:26 +0300 (IDT)
>From: Peter ####@####.####
>To: ####@####.####
>Subject: re: sdcc feature request
>
>I have a feature request:
>
>I would like code like:
>
>code char at 0x1234 foo[] = "abcd";
>
>to generate initialised data at the indicated absolute address. Assume
>that the absolute address chosen will not collide with anything
>generated by the compiler for a start. This does not happen currently,
>and no error is raised. For example, compiling something like:
The output of a statement like:
code char at 0x1234 foo[] = "abcd";
should be:
.area CODE (ABS)
.org 0x1234
_foo:
.ascii "abcd"
or equivalent. Since there is no easy way to determine if the address is
or will be used this is ignored and left to the user to fix for now
(more exactly the linker should complain if the address is reused - it
probably does, I did not check).
3. Implementation:
modify src/SDCCglue.c:emitStaticSeg() so it emits code as above for any
static (?) symbol that has an absolute address in segment code
(IS_STATIC && SPEC_ABSA && code) ( -- should check for *WHICH* storage
class it is static in and only do it for code and eeprom (at89s8252
f.ex.)).
Question: the same rule also appears in src/SDCCglue.c:emitRegularMap
and there also nothing is emitted for an absolute address. Where should
this be done ? Both places ? emitRegularMap can move symbols to the
static seg. Hmm ? Should there be an extra segment for this type of data
?
This initialised data should really be moved into a 'new' segment imho
as switching the .area before and after each absolute segment emit in
emitStaticSeg() as I implemented it now is a hack. It may break things
(anything static with an address will be defined in code - this is not
necessarily a bug it depends on what one understands under 'static
initialised @address).
4. Tiny patch against sdcc-2.4.0 (patch name for archive purposes is
sdcc-2.4.0-plp-icode-0.0.diff). This is a hack. It needs major cleaning
up imho. It could break other things.
save as: sdcc-2.4.0-plp-icode-0.0.diff
apply as in: cd src/; patch SDCCglue.c <sdcc-2.4.0-plp-icode-0.0.diff
--snip--
1196a1197
> int absflg = 0; // 1 if we print an absolute static symbol
1228a1230
>
1231,1234c1233,1259
<
< fprintf (out, "%s\t=\t0x%04x\n",
< sym->rname,
< SPEC_ADDR (sym->etype));
---
>
> // plp 2005
> if( IS_STATIC(sym->etype) &&
> SPEC_ADDR(sym->etype) )
> {
> //if(!absflg) // avoid printing unnecessarily
> fprintf( out, "\t.area CODE\t(ABS)\n");
> fprintf( out, "\t.org 0x%04X\n", SPEC_ADDR(sym->etype));
> }
> // plp 2005 : for now duplicate the code below, must clean up
> // later
> if (sym->ival) {
> fprintf (out, "%s:\n", sym->rname);
> noAlloc++;
> resolveIvalSym (sym->ival, sym->type);
> printIval (sym, sym->type, sym->ival, out);
> noAlloc--;
> /* if sym is a simple string and sym->ival is a string,
> WE don't need it anymore */
> if (IS_ARRAY(sym->type) && IS_CHAR(sym->type->next) &&
> IS_AST_SYM_VALUE(list2expr(sym->ival)) &&
> list2val(sym->ival)->sym->isstrlit)
> {
> freeStringSymbol(list2val(sym->ival)->sym);
> }
> }
> fprintf( out, "\t.area CSEG\t(CODE)\n");
--snap--
test program:
1.c:
--snip--
#include <8051.h>
code static char at 0x1234 foo[] = "abc";
code char bar = 'y';
void main(void)
{
;
}
--snap--
output assembly tail:
--snip--
.area CSEG (CODE)
.area CODE (ABS)
.org 0x1234
_foo:
.ascii "abc"
.db 0x00
.area CSEG (CODE)
_bar:
.db #0x79
.area XINIT (CODE)
--snap--
