Hi Eric,
[email protected] schreef op 2026-08-01 17:51:
Hello Maarten,
From below reply, could you please explain what you mean with:
Since .bndry is not working in the linker I would be careful with
this.
During preparation of the original example I examined both the map file
as
well as the produced binary, and they seem to confirm the desired
memory
layout:
C: 00000089 __sdcc_program_startup main
C: 00000100 _USBINT_AUTOVECTORS main
00000080: F6 E6 A8 82 20 F5 D9 80 CF 12 01 6F 80 FE #vf(.
uY.O..o.~
00000100: 02 01 71 02 01 75 02 01 79 02 01 7D #..q ..u ..y
..}
00000110: 75 81 08 12 01 81 E5 82 60 03 02 00 89 79 00 E9
#u.....e.`....y.i
Without specifying .bndry 256 this changes to:
C: 00000089 __sdcc_program_startup main
C: 0000008E _USBINT_AUTOVECTORS main
00000080: F6 E6 A8 82 20 F5 D9 80 CF 12 00 FD 80 FE 02 00 #vf(.
uY.O..}.~..
00000090: FF 02 01 03 02 01 07 02 01 0B 75 81 #. ... ...
... u.
000000A0: 08 12 01 0F E5 82 60 03 02 00 89 79 00 E9 44 00
#....e.`....y.iD.
Are you saying the former result is a lucky coincidence, and that the
linker
may not produce correct results in other circumstances?
Yes, I am afraid that is exactly what I am saying. Though it is not a
complete
coincidence of course since the linker is deterministic.
When you use .bndry in the first file you link you get a good chance
that it
works as expected. The assembler moves the data to a correct offset in
the area
segment but the linker may start the segment at a non-boundary multiple
located
place.
Kind regards,
Maarten
Eric
-----Original Message-----
From: Maarten Brock <[email protected]>
Sent: Wednesday, 22 July 2026 15:25
To: [email protected]
Subject: Re: [Sdcc-user] Cypress FX2 USB vector "table"
Hello Ian,
[email protected] schreef op 2026-06-29 12:44:
>
> extern void USBINT_AUTOVECTORS(void) __interrupt(8) __naked;
This is a good idea.
> int main(void)
Since main() has nothing to return any value to, make it return void.
> {
> __asm
> .area HOME (CODE)
> .bndry 256
> _USBINT_AUTOVECTORS::
> ljmp _USBINT_SUDAV
> .ds 1
> ljmp _USBINT_SOF
> .ds 1
> ljmp _USBINT_SUTOK
> .ds 1
> ljmp _USBINT_SUSPEND
> .ds 1
>
> // And so on...
>
> .area CSEG (CODE)
> __endasm;
>
> while (1)
> {
> }
> }
Since .bndry is not working in the linker I would be careful with
this.
Also, don't place this inside main(). Put it in a separate dummy
function,
preferably at the end of the file containing main().
static void dummy(void) __naked
{
__asm
...
__endasm;
}
Using ljmp instead of the magic number 0x02 is better IMO.
> static volatile uint8_t i = 0;
>
> void USBINT_SUDAV(void) __interrupt
> {
> i = 0;
> }
This is exactly right: __interrupt with no number.
> void USBINT_SOF(void) __interrupt
> {
> i = 1;
> }
>
> void USBINT_SUTOK(void) __interrupt
> {
> i = 2;
> }
>
> void USBINT_SUSPEND(void) __interrupt
> {
> i = 3;
> }
>
> As compiled and linked with SDCC 4.6.0, this seems to give the desired
> layout in code space.
>
> Eric
>
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