Hi,
we are using sdcc 2.4.0 (debian sarge) for uC ATMEL AT89C51ED2.
The initialization of global xdata (XISEG) is not properly performed
without option '-no-xinit-opt' when the internal XRAM of uC
is used and XISEG ends above 0xFFh.
Looking into the *.asm output shows:
1 ;--------------------------------------------------------
2 ; File Created by SDCC : FreeWare ANSI-C Compiler
3 ; Version 2.4.0 Mon Nov 6 18:07:35 2006
4
5 ;--------------------------------------------------------
6 .module ******
7 .optsdcc -mmcs51 --model-small
8 [...]
9 ;--------------------------------------------------------
10 ; global & static initialisations
11 ;--------------------------------------------------------
12 .area GSINIT (CODE)
13 .area GSFINAL (CODE)
14 .area GSINIT (CODE)
15 __sdcc_gsinit_startup:
16 mov sp,#__start__stack - 1
17 lcall __sdcc_external_startup
18 mov a,dpl
19 jz __sdcc_init_data
20 ljmp __sdcc_program_startup
21 __sdcc_init_data:
22 ; _mcs51_genXINIT() start
23 mov r1,#l_XINIT
24 mov a,r1
25 orl a,#(l_XINIT >> 8)
26 jz 00003$
27 mov r2,#((l_XINIT+255) >> 8)
28 mov dptr,#s_XINIT
29 mov r0,#s_XISEG
30 mov p2,#(s_XISEG >> 8)
31 00001$: clr a
32 movc a,@a+dptr
33 movx @r0,a
34 inc dptr
35 inc r0
36 cjne r0,#0,00002$
37 inc p2
38 00002$: djnz r1,00001$
39 djnz r2,00001$
40 mov p2,#0xFF
41 00003$:
42 ; _mcs51_genXINIT() end
The code uses movx w.r.t. r0 and p2 (lines:29-35) for writing to XISEG. This
does not work if XISEG is located in XRAM (internal memory) of the uC (as for
the T89C51ED2). IMHO it would be more portable to use 'movx @dptr, a'. This
would not depend on the physical location of the XISEG.
With sdcc option '-no-xinit-opt' the initialization is done explicitely by
assignments and works fine, but code size is larger.
This problem seems persistent also for the most recent sdcc v2.6.0. Is there
any reasion not to change _mcs51_genXINIT() accordingly? Perhaps, I overlook
some other implications?
Regards
Heiko
--
Dr. Heiko Mueller Englerstr. 28 Tel: +49 6221 89467-21
CEOS GmbH D-69126 Heidelberg Fax: +49 6221 89467-29
Germany http://www.ceos-gmbh.de
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