Maarten,
Many thanks for the excellent response so far.
Please bear with the following lengthy explanation....
It _IS_ a small app: the .map file shows all the code:-
Area Addr Size Decimal Bytes
(Attributes)
-------------------------------- ---- ---- ------- -----
------------
CSEG 407A 0CE8 = 3304. bytes
(REL,CON,CODE)
Value Global
-------- --------------------------------
0C:407A _app_entry
0C:40F7 _main
0C:40FD _Timer_Init
0C:4169 _Timer_Allocate
0C:4228 _Timer_AllocateTimeout
0C:4232 _Timer_Deallocate
0C:4270 _Timer_HasExpired
0C:42D4 _Timer_ISR0Guts
0C:43A9 _Timer_DelayUS
0C:43ED _Timer_DelayMS
0C:4419 _UART_Init
0C:4427 _UART_TxCh
0C:4431 _UART_RxAvailable
0C:4438 _UART_RxCh
0C:448D _UART_RxHexU08
0C:44B1 _UART_RxHexU16
0C:44D4 _UART_TxHexU08
0C:44EE _Console_PollOnce
0C:4673 _strlen
0C:4697 _putchar
0C:469A _HexToDec
0C:46D5 _DecToHex
0C:46F3 ___printf_no_irq
0C:4727 _do_stuff1
0C:473D _do_stuff0
0C:475E _vprintf
0C:4777 _printf
0C:4837 __print_format
0C:4D25 __mulint
0C:4D25 __mulint_dummy
0C:4D42 __gptrget
0C:4D5E __sdcc_external_startup
However the .ihx output has inserted a spurious extended address record.
<snippet>
:0E4EB900616420524F4D2F434F4445206164E9
:0E4EC7006472657373203078585858580A0A80
:014ED50000DC
:0E4ED6004F69202D2057617463682077686152
:0E4EE4007420796F7527726520646F696E67A0
:0E4EF200206661742066696E676572730A003F
:020000040001F9 ;
spurious!
:08467300AA82AB83ACF07D00CC ;
_strlen not in high segment
:0E467B008A828B838CF0124D42FEA3AA82AB82
:0746890083EE60030D80EBDE
</snippet>
I've done some more work on this, and I'm pretty sure it's a linker bug.
as/link/mcs51/lkihx.c reads as follows:-
VOID
hexRecord(unsigned addr, int rtvalIndex)
{
Addr_T chksum;
int i, overrun, bytes;
for (i = rtvalIndex, chksum = 0; i < rtcnt; i++) {
if (rtflg[i]) {
if (addr + ++chksum > 0xffff)
break;
}
}
if (chksum == 0)
return; // nothing to output
if ( (lastHexAddr > addr) && (rflag) ) { /* <==
BUG?? */
overrun = hexPageOverrun + 1;
ihxExtendedLinearAddress(lastExtendedAddress + overrun);
hexPageOverrun = overrun;
hexRecord(addr, rtvalIndex);
return;
}
... etc.
}
I think the line I've marked assumes that the output is always
ascending, therefore if (lastHexAddr > addr) it must have wrapped around
into a different bank. However, look at the .ihx output above: the
addresses are rising (E4ED, E4EE, E4EF) then the next address is 4673 -
still in the common area, but less than the previous address, so it
inserts the extended record.
I've tried a replacement as follows. This 'fixes' the problem for this
case, but is not extendable to >2 banks (and obviously I don't know the
code that well, so I may break something else...) Can you confirm I'm on
the right lines, or suggest a better way?
unsigned masked1, masked2;
masked1 = lastHexAddr & ~0xFFFFUL;
masked2 = addr & ~0xFFFFUL;
/* Is this record in the same bank as previous? */
if ( (masked1 != masked2) && (rflag) ) {
overrun = hexPageOverrun + 1;
ihxExtendedLinearAddress(lastExtendedAddress + overrun);
hexPageOverrun = overrun;
hexRecord(addr, rtvalIndex);
return;
}
I've tried to compress the app even further, to get something small
enough to submit as a how-to-reproduce sample. However the problem goes
away if I get it any smaller. So, I'm stuck with 8 compilation units and
makefile. I can send you this off-list if you need it.
Regards,
Andy
>
> Date: Wed, 28 Jan 2009 20:40:22 +0100
> From: "Maarten Brock" <sourceforge.br...@dse.nl>
> Subject: Re: [Sdcc-user] Help with code-banking
>
> Andy,
>
> If you still have code above 0x00010000 as indicated by
> the second record you mention, you either have placed
> code above that address yourself with a option for the
> linker or your program is not "a small app".
>
> Maarten
>
> > Thanks a lot Maarten,
> >
> > I've made sense of the extended address record. However one
> thing still
> > confuses me. If I build a small app that all fits in the
> common area,
> > the output.ihx still contains two extended address records,
> along the
> > lines of:-
> >
> > :020000040000FA // I guess this means bank0?
> > ..
> > <some data records>
> > ..
> > :020000040001F9 // I guess this means bank1?
> > ..
> > <more data records>
> > ..
> > :0400000500000000F7
> > :00000001FF
> >
> > I guess the linker must think the banked area starts at a
> lower address.
> > How do I set the banked area?
> > (or have I misunderstood completely?!)
> >
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